TORONTO — A large proportion of patients with hypertension and type 2 diabetes also have silent coronary artery disease, according to myocardial perfusion imaging studies presented at the Society of Nuclear Medicine's annual meeting.
Christien Côté, M.D., and colleagues carried out a prospective study to identify the prevalence and severity of silent ischemia in 595 hypertensive patients with and without type 2 diabetes. “We also wanted to establish to what extent type 2 diabetes modified the prevalence and severity of silent CAD in hypertensive patients and to assess the predictive value of risk factors for silent CAD,” said Dr. Côté, professor of medicine at Laval University, Quebec City.
Study subjects were 45 years of age and older and had either essential hypertension alone (363) or coexisting diabetes (232). None had a history of typical angina, and there were no differences in age, sex, or duration of hypertension between the two groups. Unlike previous studies, patients were selected for dipyridamole stress testing according to American Diabetes Association guidelines for coronary investigation, said Dr. Côté.
All patients underwent dipyridamole stress 99mTc-sestamibi single-photon emission CT myocardial perfusion imaging (MPI). The images were read by two blinded, experienced observers. Analysis of MPI studies showed 43% of hypertensive diabetic patients had silent CAD, as did 27% of patients with hypertension alone. “There was also a significantly greater extent of reversible ischemia in the diabetic population,” Dr. Côté said. MPI studies were also more severely abnormal in hypertensive patients with coexisting diabetes than in hypertensive patients alone.
Investigators also assessed the predictive value of risk factors on the prevalence of silent CAD. In the hypertensive population, only dyspnea was predictive of silent CAD, whereas dyspnea and proteinuria were predictive of the same ischemic defect in the hypertensive diabetic population.
The high prevalence of silent ischemia in hypertensive diabetic patients found in this study is of concern, as asymptomatic patients are unlikely to seek medical attention, and cardiovascular disease events are less likely to be prevented. CAD is the leading cause of morbidity and mortality in hypertensive patients, and their coexistence increases this risk, Dr. Côté said.