More "healthy" people are more likely to die after a heart attack

A new analysis of half a million heart attack patients has found that people with risk factors for cardiovascular disease - such as high blood pressure and high cholesterol - are more likely to survive their hospital stays than healthy people without risk factors.

The more cardiovascular risk factors patients have, adjusted for age and weight, the lower their chances of dying.

At first glance, this may seem counterintuitive, scientists say. One explanation for the finding is that people who already had heart problems may have been taking drugs, including statins and beta blockers, to protect their hearts after a heart attack.

John G. Pesney, MD, MSPH, of Watson Clinic LLC, Lakeland, Florida, and his team conducted a study of nearly 550,000 cases of newly diagnosed heart attacks, using data from the National Myocardial Infarction Registry (1994-2006), to assess the absence or presence of five leading traditional risk factors for coronary heart disease:

• Smoking
• Diabetes
• Family history of coronary heart disease
• Dyslipidemia
• Hypertension

They found that at hospitalization, 14.4% of study participants had no risk factors, 81% of participants had 1 to 3 risk factors for CHD, and 4.5% of study participants had 4 to 5 risk factors for CHD. The most common risk factor among participants with a primary myocardial infarction was hypertension (52.3%), followed by smoking (31.3%), family history of CHD (28.0%), dyslipidemia (28.0%), and diabetes mellitus (22.4%). Age among participants was inversely related to the number of risk factors for CHD, with a mean age of 56.7 years with 5 risk factors to 71.5 years with 0 risk factors.

During the study, about 50,000 patients died in hospital. Analysis of the data showed that there was an inverse relationship between the number of risk factors for coronary heart disease and overall mortality:

• in the absence of risk factors, mortality was 14.9%
• 1 risk factor - 10.9%
• 2 risk factors - 7.9%
• 3 risk factors - 5.3%
• 4 risk factors - 4.2%
• 5 risk factors - 3.6%

The study found that people with no risk factors (smoking, normal blood pressure, normal cholesterol, no history of diabetes or heart disease) were more likely to be older and 50 percent more likely to die in hospital than people with all of these risk factors.

One in seven patients who had no risk factors died after a heart attack, while one in 28 patients in the group with all five risk factors died.

The researchers explain these results by the fact that patients with a large number of risk factors received adequate treatment within the first 24 hours after their admission to the hospital.

People who have had heart problems in the past may have taken medications before their heart attack or visited a cardiologist regularly, but there is no way to know for sure.

Also, people who don't have major risk factors for heart disease may have had undetected health risks that were a major cause of heart attack and increased their chances of dying.

The study's findings mean doctors should more carefully examine seemingly "healthy" patients who have no risk factors for heart disease.

However, the study does not suggest that smoking or having high blood pressure will have a beneficial effect on your heart, the scientists stressed.

They also added: “The absence of risk factors for heart disease is not a reason not to visit your doctor for regular check-ups.”