Programmed Stimulation after Anterior Myocardial Infarction Complicated by Bundle Branch Block—Late Ventricular Tachyarrhythmias and Outcome NICHOLAS TWIDALE,* ANNE L. TONKIN, and ANDREW M. TONKIN Department of Cardiology, Flinders Medical Centre, Bedford Park, 5042, South Australia TWIDALE, N., ET AL.: Programmed stimulation after anterior myocardial infarction complicated by bundle branch block—Late ventricular tacbyarrbytbmias and outcome. One hundred and thirty con- secutive patients with anterior myocardial infarction complicated by bundle branch block were retrospec- tively analyzed. Sixty died within 1 week of infarction. Of the remaining 70 patients, 36 had electrophysiol- ogy study with programmed stimulation 8-90 (mean 20) days after infarction. Of these, nine patients (35%) who clinically had not manifested either ventricular tachycardia or ventricular jibriJIation more than 72 hours after infarction, had inducible ventricular tachycardia which was sustained more than 30 seconds in eight patients. By contrast, assessment o/atrioventricular conduction added little to clinical management, long-term follow-up, extending up to 127 months, was available both in those patients whose therapy was directed by electrophysiology study, and was assessed among the other 34 patients who survived at least 7 days after myocardial infarction, but who did not undergo electrophysiology study. While the overall mortality was 55%, the majority of deaths [22/35) occurred within 4 months of infarction and many long-term survivors enjoy a gratifying quality of life. Although programmed stimulation in survivors of anterior myocardial infarction complicated by bundle branch block may identify a high risk subgroup, a prospective randomized trial is required to define the utility of more aggressive stimulation protocols following NASPE recommendations, to identify subgroups of patients in whom newer therapeutic inter- ventions, including antiarrhythmic agents, electrical devices and surgery may be indicated. (PACE, Vol. 11, July 1988) ventricular tachycardia, bundle branch block, electrophysiology study Introduction Patients v^rith bundle branch block compli- cating anterior myocardial infarction suffer both a high in-hospital mortality and a high incidence of late sudden death after hospital discharge,^'^ at least partly because the infarct is usually asso- ciated with extensive myocardial damage. Sud- *Supported by the National Health and Medical Research Council of Australia. Address for reprints: Dr. N. Twidale, Department of Medicine, Flinders Medical Centre, Bedford Park, 5042. South Australia. Received April 6, 1987; revision July 23, 1987; revision Oc- tober 28, 1987; accepted November 6, 1987. den death might theoretically relate to further infarction, to the development of complete heart block and asystole or to a propensity for ventricu- lar tachyarrhythmias which are poorly tolerated in this group of patients who generally have poor left ventricular function.^'* It has been suggested previously that such patients should be moni- tored for up to 6 weeks after infarction,^ but this recommendation has attendant logistic problems. Accordingly, this study aimed to assess whether electrophysiology study in patients with bundle branch block might be used to identify patients at risk of subsequent ventricular tachyarrhythmias, which has been neglected by previous studies and, to consider both short and long-term fol- low-up. 1024 July 1988 PACE, Vol. 11