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Changes in ventricular activation time on the signal-averaged electrocardiogram in the first year after acute
Insights
Delayed potentials on signal-averaged electrocardiograms predict ventricular tachycardia (VT) after myocardial infarction. These potentials persist in VT patients, while non-VT patients show a decrease in delayed potentials and ventricular activation time.
Area of Science:
- Cardiology
- Electrophysiology
- Post-myocardial infarction care
Background:
- Acute myocardial infarction (MI) can lead to life-threatening ventricular arrhythmias.
- Signal-averaged electrocardiography (SAECG) is used to assess risk for ventricular tachycardia (VT).
- Delayed potentials (DP) on SAECG are a marker of arrhythmogenic substrate.
Purpose of the Study:
- To investigate the evolution of ventricular activation time and delayed potentials in the first 12 months post-MI.
- To correlate SAECG findings with the development of spontaneous ventricular tachycardia (VT).
Main Methods:
- 40 patients underwent serial SAECG recordings at 1-4 weeks, 6 months, and 12 months post-MI.
- Drug use (beta-blockers, antiarrhythmics) was discontinued before recordings.
- Patients were categorized based on the development of spontaneous VT during follow-up.
Main Results:
- All 9 patients who developed VT had initial DP; 89% retained DP at restudy.
- VT patients showed stable mean ventricular activation time (178 ms to 174 ms).
- In non-VT patients with initial DP (n=11), DP prevalence decreased to 55% by 6 months and remained stable, with a significant decrease in mean ventricular activation time (164 ms to 147 ms).
- In patients without initial DP (n=20), DP remained absent or minimal, with a slight increase in mean ventricular activation time (120 ms to 128 ms).
Conclusions:
- Persistent delayed potentials and stable ventricular activation time post-MI are associated with VT development.
- A decrease in delayed potentials and ventricular activation time in non-VT patients suggests substrate stabilization.
- SAECG is valuable for risk stratification and monitoring substrate changes after myocardial infarction.
Abstract:
Repeat signal-averaged electrocardiograms were used in 40 patients to document changes in ventricular activation time and delayed potentials in the first 12 months after acute myocardial infarction. Beta-blocking and antiarrhythmic drug use was stopped for 1 week before each recording. Patients with reinfarction during follow-up were excluded. Signal-averaged electrocardiograms were first performed 1 to 4 weeks after infarction. They were repeated at 6 and 12 months in 31 patients in whom spontaneous ventricular tachycardia (VT) did not develop and were repeated after VT in the other 9 patients. Of the 9 patients in whom VT developed, all had delayed potentials at initial study and 8 (89%) still had delayed potentials at restudy after VT. In the VT patients, mean ventricular activation time was similar before and after VT (178 ms and 174 ms, respectively). In the 11 patients who had delayed potentials initially and in whom VT did not develop, the proportion with delayed potentials was 55% (6 of 11) at 6 months and did not change (55%) at 12 months. Mean ventricular activation time in these patients was 164 ms at initial study, decreasing to 147 ms at 6 months (p less than 0.05) and 148 ms at 12 months. In 20 patients with no delayed potentials initially, none had delayed potentials at 6 months and only 2 (10%) had delayed potentials detectable at 12 months. Mean ventricular activation time in these patients increased slightly, from 120 ms at initial study to 128 ms at 12 months (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)