Left ventricular (LV) thrombus occurs in >15% of patients with anterior ST-segment elevation myocardial infarctions (aSTEMIs) who have LV ejection fractions (LVEFs) <40%. Oral anticoagulation with warfarin after aSTEMI prevents the development of an LV thrombus and related thromboembolic complications but is inconvenient and increases the risk for bleeding. Dual therapy with clopidogrel and aspirin reduces the risk for death and recurrent ischemic events after myocardial infarction and is strongly recommended for all patients with STEMIs, regardless of percutaneous coronary intervention. The benefit of warfarin in the current era of early revascularization and routine use of dual-antiplatelet therapy is uncertain. Thus, clinical cardiologists are faced with a dilemma with respect to the appropriate antithrombotic combination for patients at risk for developing LV thrombi after aSTEMIs.

We conducted an anonymous mail-in survey of all 560 adult cardiologist members of the Royal College of Physicians and Surgeons of Canada to determine the current practice patterns of Canadian cardiologists with respect to the use of dual therapy versus triple therapy (aspirin, clopidogrel, and warfarin) in patients after aSTEMI with LV dysfunction. The survey presented cardiologists with various clinical scenarios and asked them to select their preferred antithrombotic treatment.

One hundred thirty-two cardiologists responded to the survey. Sixty-five percent of respondents perceived the current incidence of LV thrombus after aSTEMI with LV dysfunction to be <10%, an estimation significantly less than that reported in published studies. Eighty-five percent of the cardiologists estimated the major bleeding risk associated with triple therapy at <5%. A recent meta-analysis suggested a risk for major bleeding at 2.2% (95% confidence interval 0.7% to 3.7%) at 30 days.

The first scenario presented a patient with aSTEMI and an LVEF <40% who was treated with thrombolysis alone; 63% of respondents preferred aspirin and warfarin, with most continuing warfarin for approximately 6 months. The second scenario presented a patient with aSTEMI and an LVEF <40% treated with percutaneous coronary intervention and a bare-metal stent; 65% favored triple therapy, with 79% opting to continue warfarin for 3 months and 40% continuing clopidogrel for >1 year. Interestingly, an observational study assessing the actual prescribed antithrombotic combinations in similar patients at discharge found the inverse, with only 35% of physicians prescribing triple therapy. The third scenario presented a patient after aSTEMI with an LVEF <40% treated with percutaneous coronary intervention with a drug-eluting stent. This patient had concomitant atrial fibrillation, with a CHADS ₂ score of 3; 89% favored triple therapy, with 75% opting for triple therapy for >1 year. Of cardiologists selecting warfarin as part of their antithrombotic combinations, 69% would bridge with parenteral anticoagulation.

Our survey suggests that most cardiologists believe that triple therapy is required in patients with aSTEMIs who develop atrial fibrillation. In patients with aSTEMIs with LV dysfunction who do not have atrial fibrillation, cardiologists are less likely to prescribe warfarin in combination with aspirin and clopidogrel, reflecting uncertainty about the benefits and risks of triple therapy in this setting. Our survey results highlight the urgent need for further studies to evaluate the most appropriate antithrombotic therapy for patients at risk for LV thrombus after aSTEMI with LV dysfunction.