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[High spontaneous variability of ventricular arrhythmias limits the evidence gained by long-term ECG studies]
Insights
Investigating ventricular arrhythmias in patients with coronary heart disease revealed significant hour-to-hour and day-to-day variability. This high spontaneous variation in ventricular premature beats (VPBs) complicates arrhythmia behavior assessment using Holter-ECG monitoring.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Technology
Context:
- Chronic coronary heart disease patients exhibit significant ventricular arrhythmia variability.
- Long-term ambulatory ECG monitoring is crucial for assessing arrhythmia patterns.
- Spontaneous fluctuations in ventricular premature beats (VPBs) can mimic drug effects.
Purpose:
- To investigate the spontaneous variability of ventricular arrhythmias.
- To assess the impact of placebo on ventricular premature beats (VPBs).
- To evaluate the reliability of Holter-ECG for individual arrhythmia behavior estimation.
Summary:
- Eight patients with coronary heart disease underwent ambulatory ECG monitoring with placebo administration.
- High hour-to-hour and day-to-day variability in VPBs was observed, with changes ranging from -84% to +940%.
- Placebo showed a significant effect on VPB counts (p < 0.001), and arrhythmia complexity also varied spontaneously.
Impact:
- High spontaneous variability complicates the interpretation of Holter-ECG recordings for individual patients.
- Findings highlight the challenge in distinguishing true antiarrhythmic effects from natural arrhythmia fluctuations.
- Emphasizes the need for careful consideration of baseline variability in clinical trials and patient management.
Abstract:
The spontaneous variability of ventricular arrhythmias was investigated in 8 patients with chronic coronary heart disease. In each patient 6 eight-hour long-term ambulatory ECG recordings were made. During the first three periods patients were without medication and during the following three periods they received a placebo b.i.d. Hour to hour variability was high in all patients. When compared with the first hour of an eight-hour period the number of ventricular premature beats (VPB) per hour in four patients declined by more than 90%, in two patients by more than 70% and in only two by less than 50%. On the other hand, increments of several hundred percent were often observed. Day to day variability of VPBs was also high. When compared with the first documented eight-hour period VPBs either decreased or increased substantially (-84% to +940%). A spontaneous reduction of VPB's for several hours may simulate an antiarrhythmic drug effect. For the group as a whole placebo had a significant effect on the number of VPBs (p less than 0.001). Beside variations of quantity, the complexity of ventricular arrhythmias (Lown classification) spontaneously changed several classes in one patient. Therefore, high spontaneous variability renders it very difficult to estimate the behaviour of ventricular arrhythmias in the individual patient with the Holter-ECG.