Variable late potentials in the Holter-ECG in patients after myocardial infarction prone to ventricular fibrillation

Background: Ventricular late potentials are found more readily in post-infa rction patients who had sustained ventricular tachycardia than in those who survived ventricular fibrillation. Hypothetically, a daytime variability o f late potentials might be responsible for this finding. Method: Therefore a conventional late potential analysis only performed onc e a day was compared to a late potential analysis in time and frequency dom ain repeatedly performed every hour in the Holter-ECG of 160 postinfarction patients (50 patients (= VT-group) with documented, sustained ventricular tachycardia (cycle-length > 230 ms), 50 patients (= VF-group) who survived, documented ventricular fibrillation and 60 patient, without ventricular ar rhythmias (= empty set VT/VF-group)). Results: The conventional analysis showed late potentials in time domain in 72 % of the patients in the VT-group. in 40 % of patients in the VF-group and in 20 % of the patients in the empty set VT/VF-group. The Holter-ECG sh owed late potentials to be permanently present in frequency domain in 66 % of the patients in the VT-group, in only 6 % in the patients in the VF-grou p and in no patient in the empty set VT/VF-group. However, in at least one analysis we detected late potentials in 84 % of patients of the VF-group in 90 % of patients in the VT-gloup and in 18 % of patients in the empty set VT/VF-group. Transiently detectable late potentials in patients of the VF-g roup were predominantly seen at heart rate accelerations in the morning hou rs, ST-segment shifts or transitory decreased heart rate variabilty. Conclusion: Post-infarction patients with sustained ventricular tachycardia predominantly have constantly detectable late potentials over 24 hours. In these patients conventional late potential is successful for post-infarcti on risk stratification at any time of the day. However, in post-infarction patients who survived ventricular fibrillation, late potentials are found t o be transitory and only detectable by Holter-ECG. Thus, late potential ana lysis performed in the Holter-ECG might improve post-infarction risk strati fication in patients prone to sudden cardiac death.