Up to a quarter of patients with diabetic retinopathy may also have unrecognized stenotic coronary artery disease, putting them at risk for heart attack or sudden cardiovascular death, reported Dr. Takayuki Ohno and colleagues at the University of Tokyo.
The investigators found that 12% of patients attending a retinocoronary clinic had undiagnosed coronary artery disease. Diabetic retinopathy (DR) is present in 3 million Japanese citizens, they said; therefore, 363,000 of these people could have unsuspected heart disease. “These estimates suggest that a large number of patients with DR … would remain without diagnoses until a fatal coronary event,” they wrote.
To test this hypothesis, the researchers opened a diabetic retinocoronary clinic in 2007. Patients with type 2 diabetes and DR who were getting outpatient ophthalmologic care were randomly referred to the clinic. There they were asked to undergo a cardiac screening, which included a cardiovascular history, physical exam, risk factor assessment, resting electrocardiography, and an exercise treadmill test. Patients who tested positive were asked to undergo exercise thallium scintigraphy or a coronary computed tomography scan. Those with abnormal results in this second tier of screening were approached for coronary angiography for further diagnosis.
Over an 18-month period, 286 patients were referred to the clinic; 214 were included in the study. Of these, 59 had nonproliferative DR and 155 had proliferative DR. Most patients (82%) were asymptomatic for cardiac problems; 12 % had previously reported atypical chest discomfort (J. Thorac. Cardiovasc. Surg. 2010;139:92-7).
A normal resting ECG was observed in 159 patients (74%). However, 4 patients (2%) had Q-waves, 39 (18%) had nonspecific ST-T changes, 9 (4%) had right bundle branch block, 2 (1%) had atrial fibrillation, and 1 (0.5%) had second-degree atrioventricular block.
A total of 172 underwent an exercise tolerance test. The results were positive in 50 (29%) and nondiagnostic in 15 (9%). A total of 33 patients underwent exercise thallium scintigraphy, with abnormal results in eight (24%). A coronary CT was performed in 24 patients, 7 of whom (29%) showed atherosclerotic coronary artery disease.
A total of 65 patients had a coronary angiography; 55 of these (26% of the entire cohort of 214) had angiographically confirmed stenotic coronary artery disease (CAD). Compared with patients without confirmed CAD, these patients were older (62 vs. 58 years) and more likely to have Q-wave or ST-T changes on resting ECG (47% vs. 21%, respectively). There were no significant differences in serum creatinine, hemoglobin A1c, or lipid levels. A total of 65 patients had a coronary angiography; 55 of these (26% of the entire cohort of 214) had angiographically confirmed stenotic coronary artery disease (CAD). Compared with patients without confirmed CAD, these patients were older (62 vs. 58 years) and more likely to have Q-wave or ST-T changes on resting ECG (47% vs. 21%, respectively). There were no significant differences in serum creatinine, HbA1c, or lipid levels.
During the clinic's daily coronary conference, CABG was recommended for 17 patients, PCI for 25, and aggressive medical therapy alone for 13. So far, 12 have undergone CABG (including 3 for whom PCI was recommended) and 27 have undergone PCI. Three refused to have any type of coronary revascularization.
During the 288-day follow-up period, all patients have remained alive with no myocardial infarction. But eight (four in each intervention group), all of whom had proliferative DR, did experience the vision-threatening complication of vitreous hemorrhage. “Progression of [diabetic retinopathy] involving vitreous hemorrhage can take place spontaneously in diabetic patients after coronary revascularization with either PCI or CABG,” but little about its prevalence is known, the authors noted.