Competing Risks of Cardiovascular Versus Noncardiovascular Death During Long-Term Follow-Up After Acute Coronary Syndromes

Abstract

Background: Understanding the relative risk of cardiovascular versus noncardiovascular death is important for designing clinical trials. These risks may differ depending on patient age, sex, and type of acute coronary syndrome (ACS).

Methods and results: IMPROVE-IT (Improved Reduction of Outcomes: Vytorin Efficacy International Trial) was a randomized controlled trial of simvastatin plus either ezetimibe or placebo following stabilized ACS. Cause of death was adjudicated by an independent committee. We compared the cumulative incidence of cardiovascular and noncardiovascular death for patients with unstable angina/non-ST-segment elevation myocardial infarction (UA/NSTEMI) and ST-segment elevation myocardial infarction (STEMI), in those <65 and ≥65 years old, and males and females, over 7 years of follow-up. Of 18 131 patients, the presenting event was STEMI for 5190 (29%) and UA/NSTEMI for 12 941 (71%); 10 173 (56%) patients were <65 years old and 7971 (44%) were ≥65 years old at presentation. UA/NSTEMI patients were older than STEMI patients, with more cardiovascular and noncardiovascular risk factors. In STEMI patients, the cumulative incidence of cardiovascular death was higher for ∼4 years following the index event, after which noncardiovascular death predominated. In UA/NSTEMI patients, the cumulative incidence of cardiovascular death remained higher than noncardiovascular death over the full follow-up period. Patients ≥65 years old and <65 years old had a higher incidence of cardiovascular death than noncardiovascular death over the entirety of follow-up. Female patients had a higher incidence of cardiovascular death than noncardiovascular death for ∼6 years following the index event; male patients had a higher incidence of cardiovascular death than noncardiovascular death over the entirety of follow-up.

Conclusions: Among post-ACS patients enrolled in a long-term clinical trial, the relative incidence of cardiovascular and noncardiovascular death differed based on type of ACS presentation and sex, but not age. These findings further delineate long-term prognosis after ACS and should inform the design of future cardiovascular outcomes trials.

Keywords: acute coronary syndrome; clinical trial; death.