Effects of percutaneous transluminal coronary angioplasty on late potentials and high frequency mid-QRS potentials.

The high frequency mid-QRS potentials and late potentials are important in coronary artery disease because they are related to the extent of ischemia and prognosis. In this study, the effects of successful percutaneous transluminal coronary angioplasty (PTCA) on these potentials were evaluated. Twenty-four patients with coronary artery disease (aged 34-67 years, 5 women, 19 men) were examined. Eight of these patients had a history of myocardial infarction (4 anterior, 3 inferior, 1 anterior and inferior). Signal averaged ECG was recorded at 40- to 250-Hz frequency ranges for late potentials and 150- to 250-Hz frequency ranges for mid-QRS potentials before PTCA, and they were repeated 1 month later. The QRS duration (107.7 +/- 9.8 to 105.3 +/- 9.3 ms, p < 0.0001) root-mean-square voltage (39.4 +/- 20.1 to 47.7 +/- 22.2 microV, p < 0.00001) and low amplitude signal duration (30.7 +/- 9.9 to 27.7 +/- 9.3 ms, p < 0.001) showed significant changes in 40- to 250-Hz ranges before and after PTCA. The same results were also obtained in the 150- to 250-Hz frequency ranges: the QRS duration decreased (90.9 +/- 9.8 to 86.5 +/- 9.1 ms, p < 0.005) and the root-mean-square voltage increased (5.5 +/- 1.6 to 6.1 +/- 1.8 microV, p < 0.00001). Thus, successful PTCA causes improvement in late potential parameters, so the risk of malign arrhythmia that affects the prognosis can be reduced. Additionally, the increase in high frequency mid-QRS potentials shows the decrease in the ischemia after PTCA.