Rear-View Mirror Observations on Bleeding in Acute Coronary Syndromes

Applying contemporary antithrombotic therapy in the secondary prevention of chronic atherosclerotic cardiovascular disease

For 4 decades, antithrombotic therapy with aspirin has been a cornerstone of secondary prevention for patients with chronic atherosclerotic cardiovascular disease (ASCVD). Unfortunately, despite the use of evidence-based therapies, patients with ASCVD continue to have recurrent major adverse cardiovascular events including death, myocardial infarction, and stroke-at a rate of approximately 2%-4% per year. To combat this continuing risk, several recent trials have evaluated the efficacy and safety of more intensive antithrombotic strategies through prolonged dual antiplatelet therapy (DAPT), combining a P2Y12 receptor antagonists and low-dose aspirin, or alternatively applying a dual pathway inhibition approach, combining low-dose non-vitamin K antagonist anticoagulant and low-dose aspirin. Both combination strategies have been shown to reduce recurrent ischemic events but at the cost of increased bleeding events. The clinical application of these antithrombotic strategies requires clinicians to assess and balance the risk of recurrent ischemic and bleeding events in an individual patient. Furthermore, clinicians may also need to adapt their antithrombotic strategies to achieve best patient outcomes, as ASCVD is a progressive disease and the risks of cardiovascular ischemic and bleeding events may shift over time. This state-of-the-art article reviews evidence from the trials and provides a practical approach to the application of DAPT and dual pathway antithrombotic therapy in the long-term management of patients with chronic ASCVD.

Effect of age on efficacy and safety of vorapaxar in patients with non-ST-segment elevation acute coronary syndrome: Insights from the Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome (TRACER) trial

BACKGROUND

Antithrombotic therapy plays an important role in the treatment of non-ST-segment elevation acute coronary syndromes (NSTE ACS) but is associated with bleeding risk. Advanced age may modify the relationship between efficacy and safety.

METHODS

Efficacy and safety of vorapaxar (a protease-activated receptor 1 antagonist) was analyzed across ages as a continuous and a categorical variable in the 12,944 patients with NSTE ACS enrolled in the TRACER trial. To evaluate the effect of age, Cox regression models were developed to estimate hazard ratios (HRs) with the adjustment of other baseline characteristics and randomized treatment for the primary efficacy composite of cardiovascular death, myocardial infarction (MI), stroke, recurrent ischemia with rehospitalization, or urgent coronary revascularization, and the primary safety composite of moderate or severe Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) bleeding.

RESULTS

The median age of the population was 64years (25th, 75th percentiles = 58, 71). Also, 1,791 patients (13.8%) were ≤54years of age, 4,968 (38.4%) were between 55 and 64 years, 3,979 (30.7%) were between 65 and 74 years, and 2,206 (17.1%) were 75years or older. Older patients had higher rates of hypertension, renal insufficiency, and previous stroke and worse Killip class. The oldest age group (≥75years) had substantially higher 2-year rates of the composite ischemic end point and moderate or severe GUSTO bleeding compared with the youngest age group (≤54years). The relationships between treatment assignment (vorapaxar vs placebo) and efficacy outcomes did not vary by age. For the primary efficacy end point, the HRs (95% CIs) comparing vorapaxar and placebo in the 4 age groups were as follows: 1.12 (0.88-1.43), 0.88 (0.76-1.02), 0.89 (0.76-1.04), and 0.88 (0.74-1.06), respectively (P value for interaction = .435). Similar to what was observed for efficacy outcomes, we did not observe any interaction between vorapaxar and age on bleeding outcomes. For the composite of moderate or severe bleeding according to the GUSTO classification, the HRs (95% CIs) comparing vorapaxar and placebo in the 4 age groups were 1.73 (0.89-3.34), 1.39 (1.04-1.86), 1.10 (0.85-1.42), and 1.73 (1.29-2.33), respectively (P value for interaction = .574).

CONCLUSION

Older patients had a greater risk for ischemic and bleeding events; however, the efficacy and safety of vorapaxar in NSTE ACS were not significantly influenced by age.