An interesting finding: in patients with myocardial infarction, hospital mortality increased consistently as the number of risk factors declined. There was also an inverse relationship between age and the number of coronary heart disease risk factors.
The authors discuss the possibility that the some of the zero risk factor group may have had risk factors unknown to the patient or not reported in the history, or may have had other factors that influence the disease, for example insulin resistance, abdominal obesity, psychosocial factors, poor nutrition, or physical inactivity.
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.
Number of Coronary Heart Disease Risk Factors and Mortality in Patients With First Myocardial Infarction