Influence of Diabetes Mellitus on Left Ventricular Function in Patients Undergoing Coronary Artery Bypass Grafting

Objectives. Left ventricular function was assessed by two-dimensional echocardiography before and one year after coronary artery bypass grafting CABG in a series of patients with severe coronary artery disease with diabetes mellitus DM and without DM non-DM . Methods. Twenty-three patients with DM and 50 patients without DM, all with no previous myocardial infarction, underwent two-dimensional echocardiography before CABG and one year after CABG, in a non-matched study. For a matched study, 31 patients without DM who had almost the same left ventricular function as DM patients at the baseline were selected to and compare the rate of improvement in left ventricular function between the DM group and the matched non-DM group. Results. In the non-matched study, patient characteristics were not significantly different between the 2 groups except for the incidence of congestive heart failure within one year before CABG, which was significantly higher in the DM group. Fractional shortening was significantly lower in the DM group at the baseline p 0.05 and also one year after CABG p 0.0001 . Significant improvement in fractional shortening was seen in the non-DM group p 0.001 , but not in the DM group. The left ventricular enddiastolic diameter LVDd was significantly larger in the DM group at the baseline p 0.01 , and was still significantly larger in the DM group at one year after CABG p 0.01 . No improvement in LVDd was seen in the DM group. In the matched study, fractional shortening of the non-DM group also showed significant improvement after CABG p 0.001 . Moreover, the rate of improvement in fractional shortening was higher in the non-DM group than in the DM group p 0.05 . LVDd tended to be larger in the DM group p NS . Conclusions. Left ventricular dysfunction and left ventricular impaired improvement were seen in the patients with DM, and CABG improved left ventricular function in the patients without DM with poor left ventricular function. These findings indicate that CABG therapy may be inadequate for improving left ventricular function in patients with DM and severe left ventricular dysfunction at the baseline.

Cardiac Pacing Suppressed Macroscopic T Wave Alternans in a Patient with Heart Failure Caused by Non-ischemic Cardiomyopathy

A 67-year-old male with dilated cardiomyopathy and chronic renal failure who received chronic hemodialysis for 9 years admitted with pulmonary edema. Three days after admission, electrocardiogram showed transient prolongation of QT interval which was followed by macroscopic T wave alternans (TWA) and ventricular fibrillation (VF). Temporary pacing from right ventricular apex suppressed TWA and VF effectively. Combined cardiac resynchronization therapy and implantable cardioverter defibrillator device was implanted for the secondary prevention of VF. Both prolongation of QT interval and TWA disappeared for 10 days after therapy and no arrhythmic event occurred since then