Estimation of coronary flow reserve by sestamibi imaging in type 2 diabetic patients with normal coronary arteries

Abstract

We assessed coronary flow reserve (CFR) by sestamibi imaging in patients with type 2 diabetes without coronary artery disease and normal coronary vessels. Dipyridamole/rest technetium 99m sestamibi imaging was performed in 33 patients with type 2 diabetes without a history of coronary artery disease and normal coronary vessels at angiography and in 12 control subjects. Myocardial blood flow (MBF) was estimated by measuring first-transit counts in the pulmonary artery and myocardial counts from tomographic images. Estimated CFR was expressed as the ratio of stress MBF to rest MBF. Rest MBF and CFR were corrected for rate-pressure product and expressed as normalized MBF and normalized CFR. At rest, estimated MBF and normalized MBF were not different in control subjects versus patients (0.98 +/- 0.4 counts x pixel(-1) x s(-1) vs 1.42 +/- 0.9 counts x pixel(-1) x s(-1) and 1.14 +/- 0.5 counts x pixel(-1) x s(-1) vs 1.61 +/- 0.9 counts x pixel(-1) x s(-1), respectively). Conversely, stress MBF was higher in control subjects than in patients (2.34 +/- 0.8 counts x pixel(-1) x s(-1) vs 1.55 +/- 0.8 counts.pixel(-1) x s(-1), P < .01). Thus estimated CFR was higher in control subjects than in patients (2.40 +/- 0.3 vs 1.36 +/- 0.8, P < .0001). After correction for the rate-pressure product, normalized CFR was still higher in control subjects than in patients (2.10 +/- 0.5 vs 1.28 +/- 0.8, P < .001). Sestamibi imaging may detect impaired coronary vascular function in response to dipyridamole in type 2 diabetic patients without a history of coronary artery disease and with normal coronary arteries.