Number of coronary heart disease risk factors and mortality in patients with first myocardial infarction

Abstract

Context: Few studies have examined the association between the number of coronary heart disease risk factors and outcomes of acute myocardial infarction in community practice.

Objective: To determine the association between the number of coronary heart disease risk factors in patients with first myocardial infarction and hospital mortality.

Design: Observational study from the National Registry of Myocardial Infarction, 1994-2006.

Patients: We examined the presence and absence of 5 major traditional coronary heart disease risk factors (hypertension, smoking, dyslipidemia, diabetes, and family history of coronary heart disease) and hospital mortality among 542,008 patients with first myocardial infarction and without prior cardiovascular disease.

Main outcome measure: All-cause in-hospital mortality.

Results: A majority (85.6%) of patients who presented with initial myocardial infarction had at least 1 of the 5 coronary heart disease risk factors, and 14.4% had none of the 5 risk factors. Age varied inversely with the number of coronary heart disease risk factors, from a mean age of 71.5 years with 0 risk factors to 56.7 years with 5 risk factors (P for trend < .001). The total number of in-hospital deaths for all causes was 50,788. Unadjusted in-hospital mortality rates were 14.9%, 10.9%, 7.9%, 5.3%, 4.2%, and 3.6% for patients with 0, 1, 2, 3, 4, and 5 risk factors, respectively. After adjusting for age and other clinical factors, there was an inverse association between the number of coronary heart disease risk factors and hospital mortality adjusted odds ratio (1.54; 95% CI, 1.23-1.94) among individuals with 0 vs 5 risk factors. This association was consistent among several age strata and important patient subgroups.

Conclusion: Among patients with incident acute myocardial infarction without prior cardiovascular disease, in-hospital mortality was inversely related to the number of coronary heart disease risk factors.

Figure 1

Total NRMI Population, Exclusions, and the Final Study Population NRMI indicates National Registry of Myocardial Infarction. Prior cardiovascular disease included previous MI, coronary heart disease, angina, heart failure, percutaneous coronary intervention, coronary artery bypass surgery, stroke, cerebrovascular disease, and peripheral vascular disease.

Figure 2

Mortality Risk of Patients With and Without Cardiovascular Risk Factors and First Myocardial Infarction In the multivariable model, candidate variables for inclusion included age (continuous), number of coronary heart disease risk factors (0 to 5), weight (<50, 50-59, 60-69, 70-79, 80-89, 90-99, 100-109, 110-119, ≥120 kg), sex, race/ethnicity (white, black, Hispanic, Asian, other), payer status (commercial, preferred provider organization, Medicare, Medicare + other, Medicaid, uninsured), systolic blood pressure, pulse, prehospital delay (0-<2, 2-<4, ≥4 hours), Killip class (I-IV), hospital characteristics with myocardial infarction volume (quartile), interventional capabilities (noninvasive, interventional, interventional without open heart surgery), region (West, South, Midwest, Northeast), hospital type (urban teaching, urban nonteaching, rural), ST-segment elevation/non–ST-segment elevation, left bundle-branch block, myocardial infarction location (anterior, other), and calendar year. P<.001 for all comparisons. OR indicates odds ratio.