RELATIONSHIP BETWEEN VENTRICULAR LATE POTENTIALS AND LEFT-VENTRICULARWALL THICKNESS ASSESSED BY MAGNETIC-RESONANCE-IMAGING IN PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION

To assess the relationship between ventricular late potentials and lef t ventricular wall thickness in infarcted areas, signal-averaged elect rocardiography (ECG; 40-250 Hz bandpass filter) and magnetic resonance imaging (MRI) were performed in 57 patients with acute myocardial inf arction (AMI) about 2 weeks after onset and in 8 normal volunteers. La te potentials were defined as the root mean square voltage of the last 40 ms (RMS V40) being < 20 muV or the filtered QRS (fQRS) > 114 ms or durations under 40 muV > 38 ms. The left ventricular wall thickness w as measured by ECG-gated MRI. Walls < 10 mm thick were considered to s how wall thinning. In order to evaluate the severity of the thinning, the wall thickness score (WTS) was also calculated. In group A (with w all thinning, n = 22), RMS V40 was smaller (24.5 +/- 19.5 vs. 55.0 +/- 27.5, p < 0.001) and fQRS longer (104.0 +/- 12.6 vs. 94.2 +/- 6.2, p < 0.001) than in group B (without wall thinning, n = 35). Late potenti als were found in 54.5% of group A and in 2.9% of group B (p < 0.001). The WTS in the group with late potentials was lower than that in the group without. These findings suggest that the occurrence of late pote ntials in patients with AMI is related to left ventricular systolic wa ll thinning.