Five-year prognosis in an incident cohort of people presenting with acute myocardial infarction

Abstract

Background: Following an AMI, it is important for patients and their physicians to appreciate the subsequent risk of death, and the potential benefits of invasive cardiac procedures and secondary preventive therapy. Studies, to-date, have focused largely on high-risk populations. We wished to determine the risk of death in a population-derived cohort of 2,887 patients after a first acute myocardial infarction (AMI).

Methods: Logistic regression and survival analysis were conducted to investigate the effect of different baseline characteristics, pharmacological therapies and revascularization procedures on coronary heart disease (CHD) and all-cause mortality outcomes.

Results: Within five years 44.4% of patients died (27.1% short-term [<30 days] and 23.7% longer-term [≥30 days]). Percutaneous transluminal coronary angioplasty (Adjusted Hazards Ratio (AHR) = 0.49, 95% Confidence Interval (CI) 0.26-0.93), β-blockers (AHR = 0.58, 95%CI 0.46-0.74) and statins (AHR = 0.60, 95%CI 0.47-0.77) were all associated with significant reductions in longer-term CHD-related mortality. However, not all patients received secondary preventive therapy (8.7%). Diabetes (AHR = 1.83, 95%CI 1.43-2.34), stroke (AHR = 1.73, 95%CI 1.35-2.22), heart failure (AHR = 1.69, 95%CI 1.28-2.22), smoking (AHR = 1.72, 95%CI 1.18-2.51) and obesity (>30 kg/m2; AHR = 1.39, 95%CI 1.01-1.90) increased the risk of longer-term mortality independent of other risk factors.

Conclusions: It is encouraging that the coronary procedure PTCA and pharmacological secondary prevention therapies were found to be strongly associated with an important reduced risk of subsequent death, although not all patients received these interventions. Smoking, being obese and having cardiovascular related disease at baseline were also associated with an increased likelihood of longer-term mortality, independent of other baseline characteristics. Thus, the provision of smoking cessation, advice on diet (for obese patients) and optimal treatment is likely to be crucial for reducing mortality in all patients after AMI.

Figure 1. Survival function for all-cause longer term (31 days to 5 years) mortality after first acute myocardial infarction by age group (n = 2104).