{"product_id":"skipping-aspirin-during-emergency-heart-attack-treatment-what-a-large-japanese-trial-found","title":"Skipping Aspirin During Emergency Heart Attack Treatment: What a Large Japanese Trial Found","description":"\u003cp\u003eA major clinical trial in Japan compared two antiplatelet strategies in patients having emergency heart attack treatment, and found that skipping aspirin and using prasugrel alone did not meet the pre-specified bar for being \"not worse\" than the standard two-drug approach. Over 12 months, the aspirin-free group had a higher rate of the combined outcome of death, stroke, or repeat heart attack (11.0% vs. 8.5%), driven largely by more myocardial infarctions, even though it caused significantly less major bleeding (5.6% vs. 8.4%). The findings do not support routine omission of aspirin at the time of primary PCI in this setting, and they reinforce the need for individualized treatment decisions.\u003c\/p\u003e\n\n\u003ch1\u003eSkipping Aspirin During Emergency Heart Attack Treatment: What a Large Japanese Trial Found\u003c\/h1\u003e\n\n\u003ch2\u003eTable of Contents\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca href=\"#ddn-key-points\"\u003eKey Points\u003c\/a\u003e\u003c\/li\u003e\n\n  \u003cli\u003e\u003ca href=\"#background\"\u003eBackground: Why This Research Matters\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#study-design\"\u003eStudy Design: A Randomized Trial at 69 Japanese Centers\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#patients\"\u003eWho Took Part: 2,216 Patients With STEMI\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#treatments\"\u003eThe Two Treatments Compared\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#primary\"\u003eKey Finding #1: The Ischemic Outcome — Aspirin-Free Care Did Not Prove \"Not Worse\"\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#bleeding\"\u003eKey Finding #2: Major Bleeding — Significantly Less With Prasugrel Alone\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#other\"\u003eOther Findings: Heart Attacks, Stent Thrombosis, and Revascularization\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#safety\"\u003eSafety Monitoring Throughout the Trial\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#limitations\"\u003eStudy Limitations\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#implications\"\u003eClinical Implications: What This Means for Patients\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#recommendations\"\u003eRecommendations for Patients and Conversations to Have With Your Cardiologist\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"#ddn-faq\"\u003eFrequently Asked Questions\u003c\/a\u003e\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"#source\"\u003eSource Information\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003c!-- ddn:keypoints:start --\u003e\n\u003ch2 id=\"ddn-key-points\"\u003eKey Points\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eIn 2,216 Japanese STEMI patients, prasugrel alone failed to show it was not worse than aspirin plus prasugrel for preventing death, stroke, or heart attack.\u003c\/li\u003e\n\u003cli\u003eThe aspirin-free strategy had more ischemic events (11.0% vs. 8.5%) but less major bleeding (5.6% vs. 8.4%) over 12 months.\u003c\/li\u003e\n\u003cli\u003eHeart attacks were more than twice as frequent without aspirin, driven by periprocedural and spontaneous events, though stent thrombosis rates were similar.\u003c\/li\u003e\n\u003cli\u003eStandard dual antiplatelet therapy with aspirin and prasugrel for 12 months remains the evidence-based default for most STEMI patients undergoing primary PCI.\u003c\/li\u003e\n\u003cli\u003ePatients at very high bleeding risk might discuss alternative strategies with their cardiologist, but routine aspirin omission is not supported by this trial.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- ddn:keypoints:end --\u003e\n\n\n\u003ch2 id=\"background\"\u003eBackground: Why This Research Matters\u003c\/h2\u003e\n\u003cp\u003eA heart attack occurs when a blockage stops blood flow to the heart muscle. STEMI (ST-segment elevation myocardial infarction) is the most severe type, producing a characteristic pattern on the electrocardiogram (ECG) and requiring immediate treatment.\u003c\/p\u003e\n\u003cp\u003eThe standard emergency treatment is primary PCI (percutaneous coronary intervention), a procedure in which a doctor threads a catheter through a blood vessel — usually in the wrist or groin — to open the blocked artery and place a stent, a small mesh tube that holds the vessel open.\u003c\/p\u003e\n\u003cp\u003eAfter PCI, guidelines from the United States and Europe recommend at least 12 months of dual antiplatelet therapy (DAPT), the combination of aspirin and a P2Y12 inhibitor such as prasugrel. Antiplatelet drugs prevent blood platelets from clumping together and forming new clots. While DAPT lowers the risk of recurrent ischemic (clot-related) events, it also increases bleeding risk, and major bleeding itself is linked to poor long-term outcomes.\u003c\/p\u003e\n\u003cp\u003eSeveral advances have changed the risk picture in recent years. Newer stents and imaging-guided procedures have reduced stent-related complications, meaning more recurrent events now arise from plaque in other parts of the arteries rather than from the stent itself. At the same time, more potent P2Y12 inhibitors have further reduced clot events, but at the cost of more bleeding.\u003c\/p\u003e\n\u003cp\u003ePrevious randomized trials testing shortened DAPT (1 to 3 months) followed by a P2Y12 inhibitor alone found lower bleeding rates without a major increase in ischemic events. However, among STEMI patients, both clot events and bleeding events tend to happen early after the procedure. In the STOPDAPT-3 trial, patients who received prasugrel alone up-front had a possible early increase in stent thrombosis (clotting inside the stent).\u003c\/p\u003e\n\u003cp\u003eUntil the PREMIUM trial, no randomized study had directly compared completely omitting aspirin up-front — giving only prasugrel from the start — against the standard full 12 months of DAPT specifically in STEMI patients undergoing primary PCI. That is the question this trial set out to answer.\u003c\/p\u003e\n\n\u003ch2 id=\"study-design\"\u003eStudy Design: A Randomized Trial at 69 Japanese Centers\u003c\/h2\u003e\n\u003cp\u003eThe PREMIUM trial (Prasugrel Monotherapy Following Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction) was an investigator-initiated, multicenter, open-label, randomized trial conducted at 69 centers in Japan. It enrolled patients from April 2023 through December 2024.\u003c\/p\u003e\n\u003cp\u003eSeveral design features are important to understand:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOpen-label\u003c\/strong\u003e means both patients and doctors knew which treatment was given, which mirrors real-world practice.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRandomized 1:1\u003c\/strong\u003e means each patient had an equal chance of being assigned to either group, balancing known and unknown factors between groups.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCentral randomization\u003c\/strong\u003e used a Web-based system with the participating site as the only balancing factor, and it happened \u003cstrong\u003ebefore\u003c\/strong\u003e the PCI procedure, while a patient was still in the emergency setting.\u003c\/li\u003e\n  \u003cli\u003eThe \u003cstrong\u003esponsor, Boston Scientific Japan\u003c\/strong\u003e, had no role in the trial design, data collection, event adjudication, statistical analysis, interpretation, or manuscript preparation.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eEligible patients were 18 years or older, had STEMI symptoms starting within 12 hours before arrival, were undergoing primary PCI with planned implantation of a platinum-chromium everolimus-eluting stent (the Synergy stent, made by Boston Scientific), and were candidates for 12 months of DAPT. Key exclusion criteria were use of oral anticoagulants (blood thinners such as warfarin or DOACs), life expectancy under 1 year, and participation in another interventional trial.\u003c\/p\u003e\n\u003cp\u003eAll patients provided written informed consent, and the trial was approved by the institutional review board at each participating center. It followed the principles of the Declaration of Helsinki.\u003c\/p\u003e\n\u003cp\u003eThe \u003cstrong\u003eprimary outcome\u003c\/strong\u003e was a composite (combined) endpoint: death from any cause, stroke, or myocardial infarction at 12 months. The researchers tested whether prasugrel monotherapy was \u003cem\u003enoninferior\u003c\/em\u003e (not worse) than DAPT, using a pre-specified margin: the upper bound of the 95% confidence interval for the hazard ratio had to be below 1.50. In plain terms, the aspirin-free approach had to show it was not more than 50% worse than DAPT on this combined outcome.\u003c\/p\u003e\n\u003cp\u003eThe \u003cstrong\u003emajor secondary outcome\u003c\/strong\u003e was major bleeding at 12 months, defined as a BARC (Bleeding Academic Research Consortium) type 3 event (nonfatal major bleeding) or type 5 event (fatal bleeding). Superiority for bleeding was to be tested only if noninferiority for the primary outcome was first established.\u003c\/p\u003e\n\u003cp\u003eOther secondary outcomes included death from any cause, cardiovascular death, noncardiovascular death, stroke, myocardial infarction, stent thrombosis, all BARC bleeding events, coronary revascularization (additional procedures to restore blood flow), a patient-oriented composite (death, stroke, heart attack, or any revascularization), and target-lesion failure (cardiovascular death, heart attack in the treated vessel, or repeat procedure on the same lesion). An independent clinical events committee, unaware of treatment assignments, adjudicated all events.\u003c\/p\u003e\n\u003cp\u003eA planned sample of 2,258 patients was calculated to give the trial 80% power, assuming a conservative event rate of 7.0% in both groups. Before the database was locked, while investigators remained unaware of group-specific results, the significance level for the noninferiority analysis was made stricter, revised from a one-sided alpha of 0.05 to 0.025, in line with established methodological guidance for noninferiority trials.\u003c\/p\u003e\n\n\u003ch2 id=\"patients\"\u003eWho Took Part: 2,216 Patients With STEMI\u003c\/h2\u003e\n\u003cp\u003eIn total, 2,268 patients underwent randomization. After exclusions (10 who did not meet eligibility criteria, 2 enrolled twice, and 44 who withdrew consent and requested deletion of their data), the full analysis population included \u003cstrong\u003e2,216 patients\u003c\/strong\u003e: 1,109 assigned to prasugrel monotherapy and 1,107 assigned to DAPT.\u003c\/p\u003e\n\u003cp\u003eThe full analysis population included all patients who were randomized and received at least one dose of prasugrel or aspirin, following the intention-to-treat principle — meaning patients were analyzed in the group to which they were assigned, regardless of whether they stayed on that treatment.\u003c\/p\u003e\n\u003cp\u003eAt 12 months, follow-up data were available for 97.8% of patients. Only 48 patients (2.2%) were lost to follow-up — a very low dropout rate that strengthens confidence in the results.\u003c\/p\u003e\n\u003cp\u003eThe two groups were well balanced at the start of the trial. The average (mean) age was 69.4 years (standard deviation ±12.5 years). Key characteristics included:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e76.6% men\u003c\/strong\u003e (855 of 1,109 in the monotherapy group; 843 of 1,107 in the DAPT group)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e38.5% had diabetes\u003c\/strong\u003e (40.4% in the monotherapy group vs. 36.7% in the DAPT group)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e75.8% vs. 74.6% had hypertension\u003c\/strong\u003e (high blood pressure)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e35.9% met criteria for high bleeding risk\u003c\/strong\u003e according to the Academic Research Consortium definition (34.2% in the monotherapy group vs. 37.6% in the DAPT group)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChronic kidney disease\u003c\/strong\u003e (estimated glomerular filtration rate below 60 ml\/min\/1.73 m²): 43.3% vs. 46.9%\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReduced pumping function\u003c\/strong\u003e (left ventricular ejection fraction below 50%): 44.4% vs. 44.6%\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSevere heart failure on arrival\u003c\/strong\u003e (Killip class III or IV): 8.6% vs. 7.8%\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMechanical circulatory support\u003c\/strong\u003e (devices like intra-aortic balloon pumps, ECMO, or microaxial flow pumps): 13.7% vs. 14.0%\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe median body-mass index (BMI) was 23.9 in the monotherapy group and 23.6 in the DAPT group. Before randomization, 5.6% of all patients were already taking aspirin and 3.1% were taking a P2Y12 inhibitor.\u003c\/p\u003e\n\u003cp\u003eTreatment was started quickly. The median time from arrival at the hospital to randomization was 43.3 minutes. After randomization, a loading dose of prasugrel was administered to 99.7% of patients overall, and a loading dose of aspirin was given to 95.7% of patients in the DAPT group.\u003c\/p\u003e\n\u003cp\u003eProcedural details reflect modern practice in Japan: radial-artery access (through the wrist) was used in 92.3% of patients, and intravascular imaging (ultrasound or optical coherence tomography inside the artery) guided the procedure in 98.6% of patients undergoing PCI. Multivessel coronary artery disease was present in 41.8% of patients with available angiographic data, and staged PCI of non-culprit lesions (additional procedures on other narrowed arteries, performed within 90 days) was done in 23.4% of patients.\u003c\/p\u003e\n\n\u003ch2 id=\"treatments\"\u003eThe Two Treatments Compared\u003c\/h2\u003e\n\u003cp\u003eThe trial compared two strategies for 12 months, with a focus on whether aspirin could safely be omitted from the very beginning:\u003c\/p\u003e\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrasugrel monotherapy group:\u003c\/strong\u003e patients received prasugrel alone, starting with a 20-mg loading dose before PCI, with no aspirin at any point. This was followed by a once-daily 3.75-mg maintenance dose for 12 months. These are the approved loading and maintenance doses in Japan.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDAPT group (standard care):\u003c\/strong\u003e patients received aspirin (a loading dose of 162 to 200 mg, unless already taking aspirin) plus prasugrel 20 mg before PCI, followed by aspirin 81 to 100 mg once daily plus prasugrel 3.75 mg once daily for 12 months.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eOne protocol detail: in the DAPT group, patients assessed as having a high risk of bleeding based on the Academic Research Consortium for High Bleeding Risk criteria had their aspirin stopped at 3 months, with P2Y12 inhibitor monotherapy continued thereafter, consistent with local clinical guidelines. This reflects real-world practice where bleeding risk is weighed against ischemic risk.\u003c\/p\u003e\n\u003cp\u003eClinical follow-up visits occurred at 1, 3, and 12 months. Guideline-directed medical therapy, including lipid-lowering therapy (statins), was strongly encouraged in both groups.\u003c\/p\u003e\n\u003cp\u003eTreatment adherence of at least 80% was observed in 91.8% of the monotherapy group (1,018 patients). In the DAPT group, at least 80% adherence was seen in 82.4% (912 patients) for aspirin and 85.9% (951 patients) for prasugrel.\u003c\/p\u003e\n\n\u003ch2 id=\"primary\"\u003eKey Finding #1: The Ischemic Outcome — Aspirin-Free Care Did Not Prove \"Not Worse\"\u003c\/h2\u003e\n\u003cp\u003eThis is the central result of the trial, and it was a negative result for the prasugrel-alone strategy.\u003c\/p\u003e\n\u003cp\u003eAt 12 months, the composite outcome of death from any cause, stroke, or myocardial infarction occurred in:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e124 patients (11.0%)\u003c\/strong\u003e in the prasugrel monotherapy group\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e94 patients (8.5%)\u003c\/strong\u003e in the DAPT group\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe hazard ratio was 1.34 (95% confidence interval, 1.02 to 1.75), with a P value of 0.40 for noninferiority. Because the upper boundary of the confidence interval (1.75) exceeded the pre-specified noninferiority margin (1.50), the trial failed to establish that prasugrel monotherapy was noninferior to DAPT.\u003c\/p\u003e\n\u003cp\u003eIn patient-friendly terms: the aspirin-free strategy was \u003cstrong\u003enot proven to be acceptable\u003c\/strong\u003e compared with standard DAPT. The results actually pointed in the opposite direction — a 34% relative increase in the risk of the combined outcome — although the confidence interval is wide, meaning the true effect could range anywhere from a 2% increase to a 75% increase in risk.\u003c\/p\u003e\n\u003cp\u003eIn absolute terms, for every 100 patients treated for 12 months, about 11 in the prasugrel-only group experienced death, stroke, or heart attack, compared with about 8 or 9 in the DAPT group. That is roughly 2 to 3 additional events per 100 patients in the aspirin-free group.\u003c\/p\u003e\n\u003cp\u003eBecause noninferiority was not established, the formal statistical plan did not proceed to test the bleeding outcome for superiority, even though the bleeding results (described below) strongly favored the monotherapy group.\u003c\/p\u003e\n\n\u003ch2 id=\"bleeding\"\u003eKey Finding #2: Major Bleeding — Significantly Less With Prasugrel Alone\u003c\/h2\u003e\n\u003cp\u003eThis is where the aspirin-free strategy showed its clearest benefit.\u003c\/p\u003e\n\u003cp\u003eMajor bleeding, defined as BARC type 3 (nonfatal major bleeding) or type 5 (fatal bleeding), occurred in:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e61 patients (5.6%)\u003c\/strong\u003e in the prasugrel monotherapy group\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e92 patients (8.4%)\u003c\/strong\u003e in the DAPT group\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe hazard ratio was 0.66 (95% confidence interval, 0.47 to 0.91), meaning the monotherapy group had about a 34% lower relative risk of major bleeding. In absolute terms, about 6 in 100 patients in the aspirin-free group had major bleeding, versus about 8 in 100 in the DAPT group — roughly 3 fewer major bleeding events per 100 patients treated.\u003c\/p\u003e\n\u003cp\u003eThis difference was driven mainly by BARC type 3 events (nonfatal major bleeding): 57 patients (5.2%) in the monotherapy group versus 89 patients (8.2%) in the DAPT group (hazard ratio 0.63; 95% CI, 0.45 to 0.88). Fatal bleeding (BARC type 5) was rare in both groups (5 patients, 0.5% vs. 4 patients, 0.4%).\u003c\/p\u003e\n\u003cp\u003eThe broader category of clinically relevant bleeding (BARC types 2, 3, or 5) also favored monotherapy: 74 patients (6.8%) versus 107 patients (9.8%) (hazard ratio 0.68; 95% CI, 0.51 to 0.92).\u003c\/p\u003e\n\u003cp\u003eBARC type 2 bleeding — overt bleeding that warrants medical attention but does not meet criteria for major bleeding — occurred in 14 patients (1.3%) vs. 18 patients (1.7%), a difference that did not reach statistical significance (hazard ratio 0.78; 95% CI, 0.39 to 1.56).\u003c\/p\u003e\n\n\u003ch2 id=\"other\"\u003eOther Findings: Heart Attacks, Stent Thrombosis, and Revascularization\u003c\/h2\u003e\n\u003cp\u003eSeveral secondary outcomes are worth highlighting because they help explain why the primary result went against the monotherapy group.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eMyocardial infarction (heart attack) was notably more common in the aspirin-free group.\u003c\/strong\u003e Overall, 31 patients (2.9%) in the monotherapy group had a heart attack during the 12 months, versus 14 patients (1.3%) in the DAPT group — a hazard ratio of 2.24 (95% CI, 1.19 to 4.21), meaning more than double the relative risk. In absolute terms, about 3 in 100 patients in the aspirin-free group had a heart attack, versus about 1 in 100 in the DAPT group.\u003c\/p\u003e\n\u003cp\u003eBreaking this down further:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePeriprocedural heart attacks\u003c\/strong\u003e (related to a procedure): 9 patients (0.8%) in the monotherapy group vs. 2 patients (0.2%) in the DAPT group (hazard ratio 4.52; 95% CI, 0.98 to 20.91). Note: because cardiac biomarker levels were already elevated at presentation from the initial STEMI, periprocedural heart attack was not counted for the index (first) PCI procedure.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpontaneous heart attacks\u003c\/strong\u003e (occurring on their own): 22 patients (2.1%) vs. 13 patients (1.2%) (hazard ratio 1.71; 95% CI, 0.86 to 3.39). This difference did not reach statistical significance on its own.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eStent thrombosis\u003c\/strong\u003e (a blood clot forming inside the stent) is a particularly feared complication because it can cause a new heart attack or sudden death. Importantly, the rates were similar between the two groups:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDefinite or probable stent thrombosis: 15 patients (1.4%) in the monotherapy group vs. 16 patients (1.5%) in the DAPT group (hazard ratio 0.94; 95% CI, 0.46 to 1.89).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThis is a reassuring finding, given earlier concerns from the STOPDAPT-3 trial about a possible early increased risk of stent thrombosis when aspirin is omitted.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeath outcomes\u003c\/strong\u003e were similar in both groups:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDeath from any cause: 74 patients (6.6%) vs. 69 patients (6.3%) — hazard ratio 1.08 (95% CI, 0.78 to 1.49)\u003c\/li\u003e\n  \u003cli\u003eDeath from cardiovascular causes: 50 patients (4.5%) vs. 47 patients (4.3%) — hazard ratio 1.07 (95% CI, 0.72 to 1.59)\u003c\/li\u003e\n  \u003cli\u003eDeath from noncardiovascular causes: 24 patients (2.2%) vs. 22 patients (2.1%) — hazard ratio 1.10 (95% CI, 0.62 to 1.96)\u003c\/li\u003e\n  \u003cli\u003eStroke: 28 patients (2.5%) vs. 21 patients (1.9%) — hazard ratio 1.34 (95% CI, 0.76 to 2.36), a difference that did not reach statistical significance\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eRevascularization\u003c\/strong\u003e (additional procedures to restore blood flow) was more frequent in the monotherapy group:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eAny coronary revascularization: 72 patients (6.8%) vs. 50 patients (4.6%) — hazard ratio 1.46 (95% CI, 1.02 to 2.09)\u003c\/li\u003e\n  \u003cli\u003eClinically driven revascularization of the target lesion (the original blockage site): 22 patients (2.1%) vs. 23 patients (2.1%) — hazard ratio 0.96 (95% CI, 0.53 to 1.72), essentially identical\u003c\/li\u003e\n  \u003cli\u003eClinically driven revascularization of nontarget lesions (other blockages): 51 patients (4.9%) vs. 32 patients (2.9%) — hazard ratio 1.62 (95% CI, 1.04 to 2.52), suggesting more events arising from disease elsewhere in the coronary arteries, not from the stented area\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eComposite and combined outcomes\u003c\/strong\u003e mirrored the primary result:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003ePatient-oriented composite outcome (death from any cause, stroke, myocardial infarction, or coronary revascularization): 167 patients (14.9%) vs. 128 patients (11.5%) — hazard ratio 1.33 (95% CI, 1.06 to 1.67)\u003c\/li\u003e\n  \u003cli\u003eTarget-lesion failure (cardiovascular death, target-vessel heart attack, or clinically driven target-lesion revascularization): 77 patients (7.0%) vs. 69 patients (6.2%) — hazard ratio 1.12 (95% CI, 0.81 to 1.55)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eRates of serious adverse events appeared similar in the two groups. As is standard in such trials, the confidence intervals for secondary outcomes were not adjusted for multiple comparisons, so these should be interpreted with some caution; they are supportive rather than definitive.\u003c\/p\u003e\n\n\u003ch2 id=\"safety\"\u003eSafety Monitoring Throughout the Trial\u003c\/h2\u003e\n\u003cp\u003eBecause the question of omitting aspirin raised genuine safety concerns, the trial included multiple layers of oversight.\u003c\/p\u003e\n\u003cp\u003eA pre-specified safety trigger required that if the absolute difference in definite stent thrombosis events between the groups reached five or more, the independent data and safety monitoring board would review unblinded data and assess whether the trial should continue. In addition, after external evidence from the STOPDAPT-3 trial suggested a possible early increased risk of stent thrombosis with aspirin omission, the protocol was amended to add an interim safety analysis after enrollment of 900 patients. That review recommended continuation of the trial.\u003c\/p\u003e\n\u003cp\u003eA subsequent ad hoc safety review after enrollment of 1,500 patients, performed under the data and safety monitoring board charter, again supported continuation. No formal interim efficacy analyses were performed, meaning the trial's outcome results were not examined early for benefit or harm in a way that could have stopped it for efficacy reasons.\u003c\/p\u003e\n\n\u003ch2 id=\"limitations\"\u003eStudy Limitations\u003c\/h2\u003e\n\u003cp\u003eEvery clinical trial has limits, and this one is no exception. These are the most important caveats to keep in mind:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOpen-label design:\u003c\/strong\u003e Both patients and physicians knew which treatment was given. This can introduce bias in how events are reported or how additional procedures are recommended, although all clinical events were centrally adjudicated by a committee unaware of treatment assignment.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eConducted entirely in Japan:\u003c\/strong\u003e The prasugrel dose used (3.75 mg daily) is the approved maintenance dose in Japan and is lower than the 10 mg daily dose used in many other countries (5 mg in some European patients). The results may not translate exactly to other dosing regimens or populations with different baseline risk profiles.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePeriprocedural heart attacks not counted for the index procedure:\u003c\/strong\u003e Because patients already had elevated cardiac biomarkers from their presenting heart attack, the definition could not capture procedure-related heart muscle damage from the initial PCI. The excess of periprocedural myocardial infarctions in the monotherapy group was driven by events related to later procedures (such as staged PCI).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpecific stent used:\u003c\/strong\u003e All patients received the Synergy platinum-chromium everolimus-eluting stent. Results might differ with other stent types, though the Synergy stent is widely used internationally.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSecondary outcomes not adjusted for multiplicity:\u003c\/strong\u003e The confidence intervals for secondary and subgroup analyses were not adjusted for multiple testing, so these findings should be viewed as exploratory and hypothesis-generating rather than definitive.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBleeding superiority not formally tested:\u003c\/strong\u003e Because noninferiority for the primary outcome was not established, the pre-specified sequential testing strategy meant the bleeding benefit of monotherapy, while large and statistically apparent, could not be formally declared as a superiority finding under the trial's hierarchy.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAdherence differed between groups:\u003c\/strong\u003e Treatment adherence of at least 80% was higher in the monotherapy group (91.8%) than in the DAPT group for aspirin (82.4%) and prasugrel (85.9%). If anything, higher adherence in the monotherapy group would tend to favor monotherapy, making the observed disadvantage more notable.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2 id=\"implications\"\u003eClinical Implications: What This Means for Patients\u003c\/h2\u003e\n\u003cp\u003eThe bottom line is clear: in this large, carefully conducted randomized trial, starting STEMI patients on prasugrel alone without aspirin did not measure up to the standard DAPT approach for preventing ischemic events over 12 months.\u003c\/p\u003e\n\u003cp\u003eThe driving force behind the difference was heart attacks — more than twice as many in the aspirin-free group. Importantly, the extra heart attacks were not from the stent itself (stent thrombosis rates were nearly identical between groups). Instead, they were more often periprocedural events related to later procedures and spontaneous events from disease progression elsewhere in the coronary arteries. The higher rate of revascularization of nontarget lesions in the monotherapy group fits this same pattern.\u003c\/p\u003e\n\u003cp\u003eFor patients, the trade-off is real and personal. The aspirin-free strategy clearly reduced major bleeding — roughly 3 fewer major bleeding events per 100 patients treated — but it came at the cost of roughly 2 to 3 additional death\/stroke\/heart attack events per 100 patients. Given that the trial's statistical design required the aspirin-free strategy to prove it was not worse than standard care, and it failed to do so, the standard of care — DAPT with aspirin and prasugrel for 12 months — remains the evidence-based default for most STEMI patients undergoing primary PCI.\u003c\/p\u003e\n\u003cp\u003eThe results also suggest nuance. Death rates were similar, and stent thrombosis was not increased with prasugrel alone. The excess risk was concentrated in nonfatal heart attacks and repeat revascularization procedures. Some patients at very high bleeding risk might still reasonably discuss an aspirin-free or abbreviated-DAPT strategy with their cardiologist, but this trial does not support making that the routine choice.\u003c\/p\u003e\n\n\u003ch2 id=\"recommendations\"\u003eRecommendations for Patients and Conversations to Have With Your Cardiologist\u003c\/h2\u003e\n\u003cp\u003eIf you or a loved one has had a STEMI treated with primary PCI, here is what this study means for your care:\u003c\/p\u003e\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStay on both medications if prescribed.\u003c\/strong\u003e The current standard of care — aspirin plus prasugrel (or another P2Y12 inhibitor) for 12 months — is supported by this trial. Do not stop either medication without talking to your cardiologist.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUnderstand the \"why\" behind each pill.\u003c\/strong\u003e Aspirin and prasugrel work in complementary ways to keep platelets from forming clots. This study suggests that removing aspirin early may leave some protection on the table, particularly against heart attacks that are not related to the stent itself.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKnow your bleeding risk.\u003c\/strong\u003e If you have a history of major bleeding, stomach ulcers, kidney disease, or other conditions that raise bleeding risk, ask your cardiologist specifically about your individual balance of ischemic and bleeding risk. The study confirms that aspirin increases bleeding; the question is whether that risk outweighs its clot-preventing benefit in your particular case.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDo not stop aspirin before a planned procedure.\u003c\/strong\u003e The excess periprocedural heart attacks in the aspirin-free group included events around later staged procedures. If you need a second procedure, your cardiologist will decide the right antiplatelet management around it — follow that advice exactly.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAddress the broader disease, not just the stent.\u003c\/strong\u003e The extra events in the aspirin-free group came largely from blockages elsewhere in the arteries. This is a reminder that after a heart attack, aggressive risk-factor control matters: taking statins as prescribed, controlling blood pressure and diabetes, and quitting smoking are all essential parts of preventing future events, regardless of which antiplatelet strategy you are on.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTake medications exactly as directed, every day.\u003c\/strong\u003e Adherence in this trial was generally high, and the results still favored DAPT. Missing doses of antiplatelet therapy after stent placement is known to increase clot risk substantially.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eThis was a rigorously conducted trial with high follow-up rates and modern procedural techniques. Its message is straightforward: for most patients having emergency PCI for STEMI, starting with aspirin plus prasugrel and continuing for 12 months remains the evidence-based approach. Aspirin omission reduced bleeding, but the price — more heart attacks — was too high to accept as a routine strategy.\u003c\/p\u003e\n\n\u003c!-- ddn:faq:start --\u003e\n\u003ch2 id=\"ddn-faq\"\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003ch3\u003eWhat did the PREMIUM trial compare in patients having emergency heart attack treatment?\u003c\/h3\u003e\n\u003cp\u003eThe trial compared two antiplatelet strategies after emergency stent placement for STEMI: prasugrel alone (no aspirin) versus standard dual antiplatelet therapy with aspirin plus prasugrel for 12 months. It included 2,216 patients in Japan and aimed to see if skipping aspirin was not worse than standard care.\u003c\/p\u003e\n\u003ch3\u003eDid skipping aspirin reduce bleeding complications after a heart attack?\u003c\/h3\u003e\n\u003cp\u003eYes. Major bleeding occurred in 5.6% of patients receiving prasugrel alone compared with 8.4% of those on aspirin plus prasugrel, about 3 fewer major bleeding events per 100 patients. However, the trial's statistical plan did not formally declare superiority because the primary ischemic outcome failed first.\u003c\/p\u003e\n\u003ch3\u003eWere heart attacks more common without aspirin in the PREMIUM trial?\u003c\/h3\u003e\n\u003cp\u003eYes. Heart attacks occurred in 2.9% of the prasugrel-only group versus 1.3% of the aspirin-plus-prasugrel group, more than double the relative risk. The increase was driven by both periprocedural heart attacks during later procedures and spontaneous heart attacks, but stent thrombosis rates were similar.\u003c\/p\u003e\n\u003ch3\u003eWho was eligible to participate in the PREMIUM trial?\u003c\/h3\u003e\n\u003cp\u003eEligible patients were 18 or older with STEMI symptoms starting within 12 hours before arrival, undergoing emergency stent placement with a specific platinum-chromium stent, and candidates for 12 months of dual antiplatelet therapy. People taking oral anticoagulants or with life expectancy under 1 year were excluded.\u003c\/p\u003e\n\u003ch3\u003eWhat does the PREMIUM trial mean for patients currently taking aspirin and prasugrel after a heart attack?\u003c\/h3\u003e\n\u003cp\u003eThe standard approach of aspirin plus prasugrel for 12 months remains the evidence-based default for most patients after emergency PCI for STEMI. Do not stop either medication without talking to your cardiologist, because the trial showed that omitting aspirin led to more heart attacks despite less bleeding.\u003c\/p\u003e\n\u003ch3\u003eCan a second opinion help me decide whether it is safe to take prasugrel alone instead of aspirin plus prasugrel after an emergency heart stent for a STEMI?\u003c\/h3\u003e\n\u003cp\u003eIn the large PREMIUM trial, starting with prasugrel alone failed to prove it was not worse than 12 months of aspirin plus prasugrel. Over 12 months, death, stroke, or repeat heart attack occurred in 11.0% with prasugrel alone versus 8.5% with dual therapy, driven by more heart attacks; major bleeding was less common (5.6% versus 8.4%). Standard care remains dual antiplatelet therapy for most patients, but bleeding risk varies. A second opinion can help individualize this trade-off. Diagnostic Detectives Network provides independent expert second opinions.\u003c\/p\u003e\n\u003c!-- ddn:faq:end --\u003e\n\n\u003ch2 id=\"source\"\u003eSource Information\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eOriginal article title:\u003c\/strong\u003e Aspirin Omission at the Time of Primary Percutaneous Coronary Intervention in STEMI\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors:\u003c\/strong\u003e K. Takahashi, K. Kozuma, Y. Morino, K. Kashiwabara, H. Otake, S. Suwa, M. Nanasato, T. Muramatsu, H. Anzai, A. Shirakabe, M. Yamamoto, Y. Asaumi, M. Sakuma, H. Okayama, K. Nakabayashi, N. Ogata, K. Jujo, K. Wakabayashi, T. Kusuyama, Y. Onishi, K. Ashida, Y. Mitsuhashi, Y. Nishimoto, S. Yamazaki, N. Kuriyama, Y. Ikari, and G. Nakazawa, for the PREMIUM Trial Investigators\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eJournal:\u003c\/strong\u003e The New England Journal of Medicine (NEJM)\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePublication details:\u003c\/strong\u003e Published online August 29, 2026, at NEJM.org; DOI: 10.1056\/NEJMoa2606997. Copyright © 2026 Massachusetts Medical Society.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c\/strong\u003e Funded by Boston Scientific Japan. ClinicalTrials.gov number: NCT05709626.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eNote:\u003c\/strong\u003e This patient-friendly article is based on peer-reviewed research. It is designed to help patients understand the study and its findings, and it does not constitute individual medical advice. Always discuss your specific treatment plan with your cardiologist or health care team.\u003c\/p\u003e","brand":"DiagnosticDetectives.Com","offers":[{"title":"Default Title","offer_id":47549382459548,"sku":null,"price":0.0,"currency_code":"RUB","in_stock":true}],"url":"https:\/\/diagnosticdetectives.ru\/products\/skipping-aspirin-during-emergency-heart-attack-treatment-what-a-large-japanese-trial-found","provider":"DiagnosticDetectives.Com","version":"1.0","type":"link"}