Atypical risk factor profile and excellent long-term outcomes of young patients treated with primary percutaneous coronary intervention for ST-elevation myocardial infarction

Abstract

Introduction:

Several studies have examined the relationship between age and clinical outcomes in patients with ST-elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (PPCI). The majority of studies have concentrated on describing elderly patients and there has been less focus on the profile and outcome of young patients suffering from STEMI. The aim of this study was to describe the clinical profile and outcomes of young patients compared with an older cohort and to establish what risk factors were associated with young patients having PPCI for STEMI.

Methods:

This was an observational cohort study of 3618 patients with STEMI treated by PPCI at a regional heart attack centre in London between January 2004 and September 2012. Clinical characteristics and outcomes in (young) patients aged ≤45 years were compared with those in (older) patients aged >45 years. The primary and main secondary outcomes were all-cause mortality and major adverse cardiovascular event rates, respectively, at a median follow-up of 3.0 (interquartile range 1.2–4.6) years.

Results:

Of the 3618 patients, 367 (10.1%) were aged ≤45 years and 3251 (89.9%) were aged >45 years. The proportion of patients aged ≤45 years increased from 8.5% to 11.5% (p=0.04) during the study period. Compared with older patients, those aged ≤45 years were more likely to be male, smokers, of South Asian ethnicity and to have a family history of premature coronary artery disease. Young patients were less likely to have a history of hypertension, hypercholesterolaemia, diabetes mellitus, previous myocardial infarction, myocardial revascularisation, or to have left ventricular systolic impairment or renal impairment. Over the follow-up period, mortality (2.7% vs. 7.6%; p<0.0001) and major adverse cardiovascular event rates (7.0% vs. 13.5%; p<0.0001) were significantly lower in patients aged ≤45 years compared with older patients. After adjustment for potential confounding factors, young age remained a predictor of reduced all cause mortality when compared with older patients (hazard ratio 0.12 (95% confidence interval 0.04–0.38)), including after incorporation of a propensity score (hazard ratio: 0.14 (95% confidence interval 0.04–0.36)).

Conclusions:

In this cohort of patients with STEMI treated by PPCI there was an increasing incidence of young patients aged ≤45 years throughout the study period. These patients were more often male, smokers and of South Asian ethnicity. Outcomes in younger patients was good. Focusing preventative strategies on smokers and high risk ethnic groups may help reduce the incidence of premature coronary artery disease.