Author + information
- Received February 2, 1987
- Revision received April 29, 1987
- Accepted May 15, 1987
- Published online October 1, 1987.
- Rita M. Watson, MD, FACC*,**,
- Janine Liberati Schwartz, RN†,
- Barry J. Maron, MD, FACC†,
- Eben Tucker, MD†,
- Douglas R. Rosing, MD, FACC† and
- Mark E. Josephson, MD, FACC‡
- ↵**Address for reprints: Rita M. Watson, MD, Assistant Professor of Medicine, Department of Medicine, Columbia Presbyterian Medical Center, 630 West 168th Street, New York, New York 10032.
This investigation was undertaken to elucidate the underlying electrophysiologic substrate in hypertrophic cardiomyopathy and to identify possible predictors of sudden death in this patient population. Programmed stimulation was performed in 18 patients aged 14 to 64 years (mean 36) believed to be at high risk for sudden death on the basis of prior cardiac arrest or syncope, nonsustained ventricular tachycardia on Holter ambulatory electrocardiographic (ECG) monitoring or a family history of frequent sudden death.
Polymorphic ventricular tachycardia that deteriorated to ventricular fibrillation was reproducibly induced in 8 (44%) of the 18 patients (Group A). This rhythm was induced in all three patients with a history of cardiac arrest. No sustained monomorphic ventricular tachycardia was induced. Group B comprised the 10 patients in whom a sustained arrhythmia could not be reproducibly initiated.
The electrophysiologic substrate was distinctly different in patients with, than in those without, inducible sustained arrhythmia. The refractory period was shorter at the right ventricular outflow tract (232 ± 22 ms) compared with the apex (264 ± 12 ms) in Group A (p < 0.005) whereas there was no difference in Group B (271 ± 25 ms versus 271 ± 13 ms). The local ventricular electrogram of most patients in both groups was prolonged and markedly multiphasic. However, 5 of the 8 Group A patients exhibited a double electrogram (V–V′) with premature stimulation compared with 1 of the 10 patients in Group B (p < 0.02). A positive R wave in lead aVR of the scalar ECG and poor R wave progression in the precordial leads were more common in Group A than in Group B (p < 0.001 and p < 0.001, respectively).
The reason for the distinctly different electrophysiologic substrate and the high prevalence of inducible polymorphic arrhythmia is unclear. It may relate to the underlying myocardial architecture in these patients, characterized by myocardial cellular disarray and fibrosis.
- Received February 2, 1987.
- Revision received April 29, 1987.
- Accepted May 15, 1987.
- American College of Cardiology Foundation