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Endocardial mapping during sinus rhythm in patients with coronary artery disease and nonsustained ventricular
A E Buxton1, R B Kleiman, K E Kindwall
1Clinical Electrophysiology Laboratory, Hospital of the University of Pennsylvania, Philadelphia.
Insights
Patients with coronary artery disease and nonsustained ventricular tachycardia (VT) who have inducible VT show delayed electrical activation and conduction slowing in the left ventricle, indicating a higher risk for sudden death.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Electrophysiology
Background:
- Nonsustained ventricular tachycardia (VT) in patients with coronary artery disease (CAD) can predict sudden cardiac death.
- Programmed stimulation can induce sustained VT in 30-50% of these patients, identifying high-risk individuals.
Purpose of the Study:
- To investigate differences in left ventricular endocardial activation and conduction between patients with inducible sustained VT and those without.
- To explore the underlying mechanisms of VT in CAD patients.
Main Methods:
- Thirty-six patients with CAD and nonsustained VT underwent programmed ventricular stimulation.
- Catheter mapping of left ventricular endocardial activation was performed.
- Electrograms were analyzed for duration, amplitude, and fractionation to assess conduction abnormalities.
Main Results:
- Sustained VT was induced in 44% of patients.
- Patients with inducible VT exhibited significantly more abnormal (48% vs. 35%) and fractionated (5.5% vs. 0.4%) electrograms.
- Delayed electrograms (15% vs. 3%) and longer local electrogram durations (128 ms vs. 100 ms) were observed in patients with inducible VT.
Conclusions:
- Patients with CAD and nonsustained VT who have inducible sustained VT demonstrate significant conduction slowing and delayed activation.
- These findings support reentry as the mechanism for induced arrhythmias in this patient group.
- Left ventricular endocardial mapping can differentiate risk stratification in CAD patients with nonsustained VT.
Abstract:
Programmed stimulation in patients with nonsustained ventricular tachycardia (VT) and coronary artery disease (CAD) induces sustained VT in 30 to 50% of patients. The presence of inducible, sustained VT identifies patients at high risk for sudden death. This study sought to determine whether patients with nonsustained VT who have inducible, sustained VT would have differences of left ventricular endocardial activation and conduction compared with those of patients without inducible, sustained VT. Thirty-six patients with CAD referred for evaluation of nonsustained VT underwent programmed ventricular stimulation and catheter mapping of left ventricular endocardial activation. Using previously validated methods, electrograms were classified as normal, abnormal or fractionated based on measurement of local electrogram duration and amplitude. Programmed stimulation induced sustained, uniform VT in 16 of 36 patients (44%). Patients with inducible, sustained, uniform VT had significantly more sites with abnormal (48%) and fractionated (5.5%) electrograms than did those without inducible VT (35% abnormal and 0.4% fractionated; p = 0.05 and 0.01, respectively). Patients with inducible VT had a mean of 15% of mapped sites displaying late electrograms versus only 3% in those without inducible VT (p < 0.01). The duration of the longest local electrogram in patients with inducible, sustained, uniform VT was 128 ms compared with 100 ms in those without inducible VT (p < 0.001). Thus, patients with CAD presenting with nonsustained VT who have inducible, sustained, uniform VT have significantly greater degrees of local conduction slowing and delayed activation than do those without inducible, sustained, uniform VT. These observations support reentry as the mechanism of the induced arrhythmias in these patients.