[Functional late potential analysis in the 24-hour electrocardiogram].

Background: It has not been investigated, whether repeated late potential analysis within 24 hours provides the recognition of functional changes and could be superior to a single analysis.

Method: Therefore we performed late potential analysis from the 24 hour Holter-ECG after validation of the method using a standard analysis system (Predictor((R))) and investigated, whether late potential appearance varied over the day and funtional changes were associated with ventricular arrhythmias. Holter tape recordings in 120 post-infarction patients were analyzed. 40 patients had venticular tachycardia (cylce length >230 ms) in the chronic phase after myocardial infarction (VT-group), 40 patients were resuscitated from ventricular fibrillation (VF-group) and 40 patients had no ventricular arrhythmias after myocardial infarction (ØVT/VF-group). The recordings were subdivided in 24 segments of 60min duration. In each segment late potentials in the time domain and the average RR-interval together with its standard deviation (SDNN) were determined.

Results: Investigation with the standard analysis system showed late potentials in 78% of the patients in the VT-group, in 30% in the VF-group and in 15% in the ØVT/VF-group. These late potentials were found analysing the Holter tape recordings in 70% of the VT-group, in 13% of the VF-group and in 5% of the ØVT/VF-group consistently in all 60min-segments. In 85% of the patients of the VF-group, compared to only 20% in the ØVT/VF-group at least in one 60min-segment within the 24hour period late potentials could be found. In patients in the VT-group, only transitory recognizable late potentials were detected predominantly during heart rate accelerations during day time and in phases of reduced heart rate variability.

Conclusions: Repeated late potential analysis from Holter tape recordings allows the recognition of functional changes and could therefore improve noninvasive risk stratification, particularly of post-infarction patients to ventricular fibrillation.