Ventricular Tachyarrhythmias in Valvular Disease
ABSTRACT & COMMENTARY
Synopsis: In patients with chronic valvular disease and ventricular tachyarrhythmias, programmed ventricular stimulation predicted future arrhythmic events, but serial drug testing is unreliable for guiding therapy.
Source: Martinez-Rubio A, et al. Circulation 1997; 96:500-508.
Patients with valvular heart disease who present with spontaneous sustained ventricular arrhythmias or syncope are unusual but difficult problems. Thus, a retrospective observational study of the use of programmed ventricular stimulation in such patients is of interest. There were 97 patients with valvular heart disease who presented with ventricular tachycardia (60%), fibrillation (18%), or syncope (22%). Prosthetic valve replacement had been done in 40% of the patients, and 15% had other corrective surgery; the others had mild-to-moderate valve disease. The patients were divided into those with ventricular overload, volume overload, or no overload based upon clinical grounds. All patients had electrophysiologic studies with programmed ventricular stimulation of up to three extra stimuli if necessary. A positive study was the induction of a twice sustained (> 30 sec) ventricular tachyarrhythmia (> 200 ms cycle length). Therapy consisted of serial drug testing and treatment first, but only if unsuccessful nonpharmacologic therapy was considered. Patient follow-up was 100% complete for an average of 51 months. Sustained VT or VF was inducible in 39% or 20% of patients, respectively. Antiarrhythmic drugs were used initially in 47%, and 30% received an implantable cardioverter defibrillator (ICD). Serial drug testing showed complete or partial suppressability in 28%. Death occurred in 17% during follow-up (40% sudden) and event-free survival (death, VT, VF) was 77%, 68%, and 61% at one, two, and three years. Arrhythmic events were predicted by VT induction during programmed stimulation and presence of left ventricular volume overload. Serial drug testing results were not predictive of freedom from events since 56%, 56%, and 53% of patients with complete, partial, or no suppression had events. Martinez-Rubio and associates conclude that in patients with chronic valvular disease and ventricular tachyarrhythmias, programmed ventricular stimulation predicted future arrhythmic events, but serial drug testing is unreliable for guiding therapy. Ventricular volume overload also predicted recurrent events, suggesting that such patients be considered early for an ICD.
COMMENT BY MICHAEL H. CRAWFORD, MD
Patients with chronic valvular disease and ventricular tachyarrhythmias are unusual; it took Martinez-Rubio et al almost 10 years to collect the 97 patients represented here. Consequently, prospective randomized trials with adequate subgroup numbers are unlikely to be forthcoming. Thus, these retrospective observational data are useful for guiding our approach to such patients.
Optimizing cardiac performance would be the obvious first step, which presumably Martinez-Rubio et al did since many of their patients had had surgery, but we do not know how many were on vasodilators, digoxin, etc. Further therapy is not detailed in the report, but many received antiarrhythmic therapy and 30% had an ICD. Also, only 78% had VT/VF documented. The others had syncope presumably due to ventricular tachyarrhythmias. The importance of this study is in the results of electrophysiologic testing (done in all) and the 100% long-term follow-up.
Despite the high number of documented VT/VF episodes in these patients, inducible ventricular tachy- arrhythmias by programmed stimulation occurred in less than half. However, those with inducible VT/VF had a poor prognosis despite therapy. (See Table.)
Table
Percentage of patients with inducible ventricular tachyarrhythmias who experienced events
Induced Rhythm Event Sudden Death Other Arrhythmic
VF 5 32
Nonsustained VT 2.5 25
Those with sustained, induced VT had the highest frequency of subsequent events. Also, the hemodynamic burden was predictive. Those with left ventricular volume overload had the highest incidence of subsequent events (57%) as compared to those with LV pressure overload (21%). Those with right ventricular overload had more events (70%) compared to those with LV overload (54%), but only LV volume overload was correlated with an increase in events. Patients with inducible VT and LV volume overload had the highest observed risk (80%).
Based upon these results, Martinez-Rubio et al recommend that patients with chronic valvular disease and documented VT/VF or syncope undergo electrophysiologic testing with programmed ventricular stimulation. Those with inducible sustained monomorphic VT and LV volume overload clinically should be considered candidates for an ICD. Presumably, the approach in the rest would be antiarrhythmic drug therapy but not electrophysiologic testing to determine efficacy, since it was not predictive. Clinical assessment or Holter monitoring would be the alternative methods of determining drug success. Neither approach was stated as preferred by Martinez-Rubio et al. Given these findings, it could be argued that only patients with LV volume overload undergo programmed stimulation since those with inducible VT are the only ones Martinez-Rubio et al recommend for immediate consideration of an ICD. All others could undergo empiric drug therapy first since it is hard to imagine not treating those with documented VT/VF even if they had a negative stimulation study. In the majority of the patients, electrophysiologic studies could be reserved for the drug failures. On the other hand, all patients with inducible VT may be candidates for an ICD, given the high observed event rate no matter what hemodynamic load they had. Thus, in those with lesions other than LV volume overload, considerable individual judgment is required, coupled with consideration of the patient’s wishes.
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