Patients with type 2 diabetes mellitus (T2DM) might have subclinical myocardial dysfunction identified at rest or unmasked during exercise. We examined the correlates of the myocardial exercise response in patients with T2DM. Myocardial dysfunction was sought during at rest and exercise echocardiography in 167 healthy patients with T2DM (97 men, 55 ± 10 years). Myocardial ischemia was excluded using stress echocardiography. Standard echocardiography and color tissue Doppler imaging measures (early diastolic tissue velocity [Em], strain, and strain rate) were acquired at baseline and peak stress. The calibrated integrated backscatter was calculated from the at rest parasternal long-axis view. The longitudinal diastolic functional reserve index after exercise was defined as ΔEm [1 - (1/Em(base))]. The clinical, anthropometric, and metabolic data were collected at rest and stress. Subclinical myocardial dysfunction at baseline (n = 24) was independently associated with weight (odds ratio [OR] 1.02, p = 0.04) and hemoglobin A1c (OR 1.36, p = 0.03). This group displayed an impaired exercise response that was independently associated with a reduced exercise capacity (OR 0.84, p = 0.034) and longitudinal diastolic functional reserve index (OR 0.69, p = 0.001). Inducible myocardial dysfunction (stress Em <-9.9 cm/s) was identified after exercise in 70 of the remaining 143 subjects. This finding was associated with calibrated integrated backscatter (OR 1.08, p = 0.04) and lower peak heart rate (OR 0.97, p = 0.002) but not metabolic control. The intensity of the metabolic derangement in patients with T2DM was associated with subclinical at rest myocardial dysfunction, but not with the myocardial exercise response. In conclusion, the association of an abnormal stress response with nonmetabolic factors, including backscatter and blunted peak heart rate, suggests potential roles for myocardial fibrosis and cardiac autonomic neuropathy in patients with nonischemic diabetic heart disease.
Copyright © 2011 Elsevier Inc. All rights reserved.