Background: P-wave signal averaged ECG has been used to detect atrial late potentials that were found in paroxysmal atrial fibrillation. Ischemia is supposed to trigger ventricular late potentials, which indicate an elevated risk for ventricular tachycardia. Preexistent ventricular late potentials measured by ventricular signal averaged ECG is supposed to be eliminated by successful PTCA.
Methods: We examined the incidence of atrial late potentials in patients with a proximal stenosis of the right coronary artery and new onset of atrial fibrillation. Furthermore, we investigated the anti-ischemic effect of a successful percutaneous transluminal coronary angioplasty.(PTCA) of the right coronary artery. P-wave signal averaged ECG from 23 patients who had a PTCA of the right coronary artery (group A) were compared to age, sex, and disease-matched control subjects (group B) one day before, one day after, and one month after PTCA.
Results: A new appearance of paroxysmal atrial fibrillation was presented in eight patients before PTCA (group A1) of group A. Patients with a stenosis of the right coronary artery had a significantly higher incidence of supraventricular extrasystoles in a 24-hour-Holter ECG (131.1 +/- 45.4 vs 17.1 +/- 18.9, P < 0.0002). The duration of the filtered P wave was longer (124.8 +/- 11.9 vs 118.5 +/- 10.1 ms, P < 0.04) and the root mean square of the last 20 ms (RMS 20) was significantly lower in group A than in group B (2.87 +/- 1.09 vs 3.97 +/- 1.12 micro V, P < 0.01). A successful PTCA caused an increase in RMS 20 (2.87 +/- 1.11 vs 4.19 +/- 1.19 microV, P < 0.02) and a decrease in filtered P-wave duration (124.8 +/- 11.9 vs 118.4 +/- 10.4 ms, P < 0.04). Preexistent atrial late potentials were found among 15 patients before PTCA. After successful PTCA only 3 out of 15 patients were affected (P < 0.0004) after one day, as well as after one month. All patients with a history of atrial fibrillation did not suffer from an arrhythmic recurrence within the following six months after successful PTCA.
Conclusion: A stenosis of the right coronary artery is associated with atrial late potentials. A successful PTCA of the right coronary artery eliminates preexistent atrial late potentials and may reduce the risk of atrial fibrillation.