Heart attack patients with diabetes or a cluster of cardiovascular risk factors known as metabolic syndrome have an increased risk of another heart attack, stroke or death, but patients who lost weight after their heart attacks were less likely to become diabetic, according to a new study in the July 19, 2005, issue of the Journal of the American College of Cardiology.
“Metabolic syndrome had a strong impact in the prognosis of patients with previous heart attack,” said Roberto Marchioli, M.D., at the Consorzio Mario Negri Sud in Santa Maria Imbaro, Italy. “The diagnosis of metabolic syndrome in post-heart attack patients indicated a high risk of cardiovascular events as well as of late onset diabetes. But the study also showed that weight reduction in overweight metabolic syndrome patients had a favorable impact on prognosis,” he said.
“The most important clinical consequence of this analysis is that lifestyle modification (for example, weight reduction) has a very favorable prognosis in overweight metabolic syndrome patients. Patients who achieved even modest weight reduction significantly reduced their risk of late onset diabetes,” Dr. Marchioli said.
Metabolic syndrome is characterized by a cluster of risk factors related to insulin resistance and is considered to be an early indicator of impaired glucose metabolism; thus, these patients are at high risk of developing diabetes, which is strongly related to heart disease risk.
The researchers, including lead author Giacomo Levantesi, M.D., analyzed data on 11,323 patients who had suffered a recent heart attack. The information was originally collected as part of the GISSI-Prevenzione Study that was designed to study the effects of polyunsaturated fatty acid and vitamin E supplements on heart attack patients.
“It is the largest analysis that allows us to assess the impact of metabolic syndrome in patients with established coronary artery disease. Up to now, evidence on the role of metabolic syndrome in cardiovascular disease came mainly from studies in primary prevention; that is, preventing the first heart attack, and the real impact of metabolic syndrome in a large population of post-heart attack patients had not been studied before,” Dr. Marchioli said.
At the start of the study, about one in five (21 percent) of the heart attack patients had diabetes. Almost one in three (29 percent) had metabolic syndrome, and by the end of follow-up three-and-a-half years later, the patients with metabolic syndrome were almost twice as likely to develop diabetes (93 percent) as were the patients without metabolic syndrome.
As compared with control subjects, who had suffered a heart attack but did not have diabetes or metabolic syndrome, the probability of death and cardiovascular events (heart attack or stroke) were higher in both metabolic syndrome (29 percent higher death rate, p = 0.002; 23 percent higher rate of cardiovascular events, p = 0.005) and diabetic patients (68 percent higher death rate, p <0.0001; 47 percent higher rate of cardiovascular events, p <0.0001). Diabetic patients were more likely to be hospitalized for congestive heart failure (89 higher rate, p < 0.0003).
Patients who reduced their weight by 6 percent to 10 percent had an 18 percent lower risk of developing diabetes during the study. Those who lost more than 10 percent of their weight cut their diabetes risk by 41 percent. The patients who gained weight during the study had a higher risk of developing diabetes.
“Metabolic syndrome is an independent, strong predictor of risk of cardiovascular events as well as of late onset diabetes in patients with previous heart attack. Lifestyle modification and in particular body weight reduction in overweight patients significantly reduced the aforementioned risks,” Dr. Marchioli said.
Dr. Marchioli noted that the GISSI-Prevenzione Study was not originally designed to investigate diabetes and metabolic syndrome in these heart attack patients and that some caution should be used in interpreting the results of this sort of re-analysis of study data.
Nathan D. Wong, Ph.D., F.A.C.C., at the University of California in Irvine, who was not connected with this study, highlighted the fact that about half of the heart attack patients in this very large population had either diabetes or metabolic syndrome.
“This underscores the importance of screening for metabolic syndrome, even if diabetes is not present, in cardiac patients. Moreover, this report shows that weight reduction in such patients is associated with an improved long-term outcome,” Dr. Wong said.