Author + information
- Received March 7, 1988
- Revision received May 5, 1988
- Accepted May 12, 1988
- Published online October 1, 1988.
- Dennis L. Kuchar, MD, FRACP1,∗,a,
- Jeffrey Rottman, MD1,2,
- Eric Berger, MD1,
- Charles S. Freeman, RN1,
- Hasan Garan, MD, FACC1,1 and
- Jeremy N. Ruskin, MD, FACC1
- ↵∗Address for reprints: Dennis Kuchar, MD, 3 Plowman Street, North Bondi, New South Wales, Australia, 2026.
This study investigated whether data available after the initial electrophysiologic study in patients with sustained ventricular tachyarrhythmia could identify those patients in whom serial drug testing is likely to be efficacious. One hundred six patients with inducible sustained ventricular tachyarrhythmia, whose initial study included short-term drug testing with intravenous procainamide, were evaluated. The baseline arrhythmia induced (in the absence of all antiarrhythmic drugs) was monomorphic tachycardia with a cycle length >200 ms in 81 patients and ventricular flutter or fibrillation in the remaining 25 patients. After intravenous infusion of procainamide (1,250 ± 300 mg), a ventricular tachyarrhythmia could still be induced in 80 patients during testing with up to three extrastimuli. Serial drug testing with one to four trials of oral conventional and investigational agents was then undertaken.
Evaluation of 15 clinical, hemodynamic and electrophys-iologic variables by stepwise logistic regression identified two independent predictors of successful response to oral antiarrhythmic drugs: 1) noninducibility of ventricular tachycardia after intravenous procainamide (p < 0.001), and 2) left ventricular ejection fraction ≥40% (p < 0.05). Subgroup analysis combining each of these variables identified patients with a high, intermediate or low probability of finding a successful oral drug regimen. Patents whose arrhythmia was suppressed by intravenous procainamide had a 100% likelihood (if left ventricular ejection fraction was ≥40%) or an 87% likelihood (if ejection fraction was <40%) of responding to an oral regimen. Patients whose arrhythmia was still inducible after intravenous procainamide and had an ejection fraction ≥40% had an intermediate likelihood (46%) of oral drug response. Patients with persistent ventricular tachycardia after intravenous procainamide and an ejection fraction < 40% had a low probability (19%) of successful response to an oral antiarrhythmic regimen.
Hence, patients who are unlikely to benefit from serial drug testing can be identified with use of a simple algorithm incorporating the left ventricular ejection fraction and the response to intravenous procainamide at the initial electrophysiologic study. Early consideration of an implantable device or arrhythmia surgery may be appropriate for such patients.
- Received March 7, 1988.
- Revision received May 5, 1988.
- Accepted May 12, 1988.