Having fewer risk factors linked to increased mortality after first MI
MedWire News: The number of coronary heart disease (CHD) risk factors that a patient with incident acute myocardial infarction (MI) has is inversely associated with in-hospital mortality, study findings show.
The report should dispel the "myth" that a large number of MI patients may not have traditional CHD risk factors, write John Canto (Watson Clinic LLP, Lakeland, Florida, USA) and colleagues.
The observational study involved 542,008 patients who experienced their first MI between 1994 and 2006, and had no prior cardiovascular disease. The researchers analyzed five major traditional CHD risk factors: hypertension, smoking, dyslipidemia, diabetes, and family history of CHD, as well as hospital mortality among these patients.
They found that the majority (85.6%) of patients who presented with initial MI had at least one of the five CHD risk factors, and 14.4% had none of the risk factors.
There was a significant inverse association between age at initial MI and the number of risk factors (p<0.001). Indeed, a mean age of 71.5 years was associated with having no risk factors, while a mean of 56.7 years was associated with having five risk factors.
In total, 50,788 individuals with first MI died. The unadjusted mortality rates for patients with no, one, two, three, four, and five risk factors were 14.9%, 10.9%, 7.9%, 5.3%, 4.2%, and 3.6%, respectively.
After adjusting for age and clinical factors, there was a significant inverse association between the number of CHD risk factors present at hospitalization and risk for hospital mortality (p<0.001).
"MI patients with few or no risk factors received fewer evidence-based medications and invasive cardiac procedures, and this undertreatment may in part have contributed to worse outcome," the authors suggest.
They point out that the presence of risk factors before first MI may also modify medical management, and could help explain the inverse association between number of risk factors and mortality.
Canto and team conclude: "Future studies should seek to gain insight into the possible explanation of such an association."
By Piriya Mahendra