Improved results in the operative management of ventricular tachycardia related to inferior wall infarction. Importance of the annular isthmus.

Ventricular tachycardia associated with inferior wall myocardial infarction has had a lower surgical cure rate with localized subendocardial resection than ventricular tachycardia related to anterior infarction. Some investigators have advocated visually directed extensive subendocardial resection, including resection of the papillary muscles and mitral valve replacement, even without documenting the origin of ventricular tachycardia at these sites. We have operated on 46 patients (43 men and three women) for ventricular tachycardia associated with inferior wall myocardial infarction. Thirty-one consecutive patients (Group I) had standard localized subendocardial resection. Two patients in this group had mitral valve replacement for mitral insufficiency. Fifteen consecutive recent patients (Group II) underwent subendocardial resection plus focal endocardial cryoablation (3 minutes at -70 degrees C) of the annular isthmus. The annular isthmus is defined as the ventricular muscle between the basal end of the ventriculotomy and the mitral valve anulus. In Group I there were four operative deaths (13%). Ventricular tachycardia was noninducible in 15 of 27 operative survivors (56%) at postoperative electrophysiologic studies. In Group II there was one operative death (7%) and 13 of 14 survivors (93%) had no inducible ventricular tachycardia at postoperative electrophysiologic studies (p less than 0.01 versus Group I). No Group II patient required mitral valve replacement. Six operative survivors in Group II had intraoperative activation maps consistent with macroreentry incorporating the annular isthmus. Group I and Group II were indistinguishable in terms of preoperative hemodynamics, number of coronary arteries diseased, or the presence of left ventricular aneurysm. These results suggest that subendocardial resection with additional cryoablation of the annular isthmus results in improved control of ventricular tachycardia in patients with ventricular tachycardia associated with inferior wall myocardial infarction. Mitral valve replacement is not required unless intrinsic mitral valve disease is present. These data also suggest that the annular isthmus is a critical component of the reentrant circuit in these tachycardias.