Related Experiment Videos
Functional changes of ventricular late potentials by provocation with increase of heart rate. Evaluation during
P Steinbigler1, R Haberl, C Jeleazcov
1Medical Hospital 1, University of Munich, München, Germany.
Insights
Increasing heart rate can reveal hidden late potentials in patients at risk for ventricular arrhythmias after myocardial infarction. This method improves detection of these dangerous heart rhythm abnormalities.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Standard methods often miss late potentials in 20-30% of post-myocardial infarction patients with ventricular arrhythmias.
- These patients may exhibit transient delayed ventricular activation during elevated heart rates.
Purpose of the Study:
- To investigate if increasing heart rate can unmask otherwise undetectable late potentials.
- To assess the utility of heart rate augmentation in identifying patients at risk for malignant ventricular arrhythmias.
Main Methods:
- Fifty post-myocardial infarction patients underwent atrial pacing at 100 and 120 bpm.
- Surface electrocardiograms were analyzed in time and frequency domains before and during pacing.
- Patients were stratified based on history of ventricular tachycardia, ventricular fibrillation, or no arrhythmias.
Main Results:
- Atrial pacing unmasked late potentials in a significant proportion of patients, particularly those with a history of ventricular arrhythmias.
- Pacing shifted pre-existing late potentials and increased their magnitude, with variations based on infarction location.
- Late potentials were provoked by pacing in patients who did not show them during sinus rhythm.
Conclusions:
- Increased heart rate effectively unmasks late potentials in patients susceptible to malignant ventricular arrhythmias.
- Functional late potential analysis during stress tests requires adequate heart rate response for accurate risk assessment.
- This approach may identify high-risk patients missed by conventional late potential analysis.
Background:
Standard methods fail to reveal late potentials in 20 to 30% of patients with ventricular arrhythmias after myocardial infarction. However, these patients may develop transient delayed ventricular activation during increases in heart rate.
Methods And Results:
Atrial pacing was performed, at the rates of 100 min-1 and 120 min-1, in 50 patients after myocardial infarction. Twenty-six patients had a history of documented, sustained ventricular tachycardia, 12 had a history of ventricular fibrillation and 12 no history of ventricular arrhythmias. The low-noise surface electrocardiogram was analysed before and during atrial pacing in the time and frequency domains. Fifteen of 26 patients with ventricular tachycardia, four of 12 with ventricular fibrillation and three of 12 without ventricular arrhythmias experienced late potentials during sinus rhythm. Atrial pacing led to a shift of 26 +/- 15 ms of preexistent late potentials into the ST segment, this being greater in patients with anterior infarctions and to an increase in magnitude in patients with inferior infarctions. In patients without late potentials during sinus rhythm, atrial pacing provoked late potentials in eight of 11 patients with ventricular tachycardia, in four of eight patients with ventricular fibrillation and in one of nine patients without ventricular arrhythmias. Low amplitude signals (LAS) were increased in patients after inferior and filtered QRS in patients after anterior infarction. In 10 patients without cardiac disease no late potentials were detectable in the time and frequency domain either at rest or during increased heart rate.
Conclusions:
Increase in heart rate may unmask late potentials in patients prone to malignant ventricular arrhythmias. Therefore, functional late potential analysis with non-invasive clinical stress tests, i.e. exercise tests, should be performed only with an adequate rate response. This might identify patients at risk of malignant ventricular arrhythmias otherwise not identified with conventional late potential analysis.