SNOWMASS, COLO. — The complaint of shortness of breath in a diabetic patient without known coronary artery disease is a red flag that should trigger an extensive cardiovascular work-up including stress myocardial perfusion imaging, Dr. George A. Beller said at a conference sponsored by the Society for Cardiac Angiography and Interventions.
Recent studies strongly suggest that exertional dyspnea in a diabetic patient may be a much more ominous symptom than exertional angina, according to Dr. Beller, professor of internal medicine and chief of the division of cardiovascular medicine at the University of Virginia, Charlottesville.
“Whether this is an angina equivalent or a marker of silent ischemia with inducible ischemic left ventricular dysfunction reflecting more severe coronary artery disease, compared with diabetic patients presenting with angina, we really don't know yet. But I am very impressed that event rates are so much higher in diabetic patients presenting with dyspnea than angina,” added Dr. Beller, a former president of the American College of Cardiology.
For example, investigators at Cedars-Sinai Medical Center in Los Angeles recently reported on 1,737 consecutive diabetic patients without known coronary artery disease (CAD) who underwent single-photon emission computed tomography (SPECT) myocardial perfusion imaging, of whom 1,430 were followed for a median of 2 years.
Objective evidence of CAD was found on SPECT in 39% of the 826 asymptomatic diabetic patients, in 44% of those with angina, and in 51% of the 151 patients with dyspnea.
The outcome was three times worse in diabetic patients with shortness of breath. The annual rate of cardiac death or nonfatal MI was 7.7% in patients with dyspnea as their predominant symptom, 3.2% in those with angina, and 2.2% in asymptomatic diabetic patients. In patients with SPECT evidence of CAD, the major event rate increased to 13.2% in patients with shortness of breath, 5.6% in those with angina, and 3.4% in asymptomatic diabetic patients (Eur. Heart J. 2004;25:543–50).
Dr. Beller noted that the importance of dyspnea also was recently underscored in nondiabetic patients. Another Cedars-Sinai study, involving 17,991 patients who underwent SPECT and were followed for a mean of 2.7 years, concluded that in patients with no known history of CAD, those with self-reported dyspnea were four times as likely to experience sudden cardiac death as asymptomatic patients and more than twice as likely to experience it as patients with typical angina (N. Engl. J. Med. 2005;353:1889–98).
But Dr. Beller focused mainly on dyspnea in diabetic patients, for two reasons: cardiovascular event rates in these patients are much higher than in nondiabetic patients, and the diabetic population is skyrocketing as a result of the obesity epidemic.
Several recent studies highlight the existence of a large number of asymptomatic diabetic patients with severe CAD. In a Mayo Clinic study of more than 4,700 diabetic patients without clinically apparent CAD referred for SPECT, 58% of the asymptomatic patients and 60% of the symptomatic ones had abnormal scans. And 20% of asymptomatic and 22% of symptomatic diabetic patients had high-risk scans involving multivessel disease and/or extensive ischemia, compared with just 13% of more than 16,000 symptomatic nondiabetic patients and 11% of more than 6,000 asymptomatic nondiabetic patients.
Exertional dyspnea in a diabetic patient may be a much more ominous symptom than exertional angina. DR. BELLER