LEFT-VENTRICULAR FUNCTION AND EXERCISE TOLERANCE IN PATIENTS WITH TYPE-II DIABETES-MELLITUS

Background: Left ventricular (LV) preload changes may alter exercise t olerance (ET), probably lessening activation of the Maestrini-Starling mechanism. Reduced LV filling (pre load) during the diastolic phase, usually impaired in diabetic patients, could affect ventricular functi on. Hypothesis: To evaluate the relationship between some echocardiogr aphic LV function indices and ET, 24 patients (age 43-75 years, mean 5 4 +/- 13 years, Group A) with type II diabetes mellitus (DM), nor suff ering from other pathologies, and for whom the ergometric stress test (EST) resulted in an early interruption because of muscular fatigue an d/or dyspnea, and 14 patients (age 38-70 years, mean 53 +/- 12 years, Group B) with type II DM and maximal ergometric stress test, used as c ontrol group, were studied. Methods: The EST was performed by increasi ng the load by 25 W every 2 min; its duration was used as an ET index and correlated with clinical parameters of LV function obtained with M -mode, two-dimensional, and Doppler echocardiography. Results: No pati ent in either Group A or Group B showed a high systolic blood pressure value at rest and/or an LV hypertrophy and/or an alteration of systol ic functional indices. In neither group was there significant correlat ion between ET and duration of DM, basal heart rate, basal and max sys tolic blood pressure, and EF values. Linear regression analysis showed a significant correlation between Doppler parameters of the diastolic function and ET index in Group A, while there was no significant corr elation in Group B. Conclusion: From these data we can deduce that in absence of left systolic ventricular dysfunction the impairment of LV relaxation in DM can influence exercise tolerance, probably by limitin g activation of the contractile reserve.