Incidence and prognostic significance of asymptomatic ischaemia in patients with sustained ventricular arrhythmias.

The role of ischaemia in the natural history of sustained monomorphic ventricular tachycardia not related to acute myocardial infarction is not well documented. We examined 38 patients (mean age 60 years, mean ejection fraction 33%) with programmed electric stimulation and thallium scintigraphy to study the presence of perfusion defects and to assess its prognostic significance. Reversible perfusion defects (RPD), alone or in combination, were seen in 17 patients (44.7%), persistent perfusion defects (PPD) in 31 (81.5%), and RPD and PRD combined existed in 14 patients (37%). Normal scintigrams were obtained in only four patients. Segmental analysis gave a mean 'infarction score' (number of PPDs on a total of 15 segments) of 4.2; the mean 'ischaemia' score (number of RPDs) was 1.2. Recurrence of tachycardia or sudden death was observed in 14 patients during a follow-up of 17 +/- 13 months. The predictive value (PV) of the presence of a RPD for recurrence was 63%, the PV of its absence was 82%; the predictive accuracy was 74% (P = 0.0069). This was as important as the data obtained with the drug studies (+PV 83%; -PV 86%; overall PV 83%, P = 0.002). The mean ischaemia score was 3.3 in the group with recurrence and 2 in the patients without recurrence. As pharmacological studies are only feasible in a subgroup with inducible tachycardia, thallium scintigraphy is of benefit to a larger group for predicting effective drug therapy and the risk of recurrence.