Septal myectomy after previous septal artery ablation in hypertrophic cardiomyopathy

OBJECTIVES: To review our institution's experience with patients who failed to benefit from septal artery ablation, which necessitated subsequent septal myectomy, and to examine reasons for ablation failure and outcome of myectomy after ablation. PATIENTS AND METHODS: Of 550 patients who underwent septal myectomy at Mayo Clinic Rochester between January 1, 1999, and December 31, 2006, 16 (3%) had had a total of 22 previous septal artery ablations. This subset of 16 patients was analyzed and compared with a reference group of 120 patients whose septal artery ablations were performed at our institution during this period. Angiograms obtained during septal ablation were available for 13 (81%) of 16 patients in this series and were reviewed by 2 interventional cardiologists (R.A.N, and S.R.O.). These cardiologists also reviewed preoperative and postoperative echocardiography data, hospital course, and follow-up data to compile a list of characteristics that could have contributed to failed ablation. RESULTS: The median age of the patients at operation was 65 years (Interquartile range [IQR], 52-72 years), and interval between ablation and myectomy was 409 days (IQR, 162-568 days). Angiograms revealed 2 failed procedures secondary to technical error. One patient had a relatively large first septal perforator with a large resting gradient. In 10 patients no septal perforators supplying the proximal septum were identified. Postoperatively, mitral regurgitation decreased from 3.00 to 1.00 (P<.001), and left ventricular outflow tract gradient decreased from 75 mm Hg to 0 mm Hg (IQR, 0-29 mm Hg; P<.001). Two patients died after surgery: 1 patient developed multiple-organ system failure on post-operative day 7, and 1 patient developed arrhythmia on postoperative day 21. Patients with previous septal artery ablation were older (P=.04), were more likely to have preoperative permanent pacemakers or implantable cardioverter-defibrillators (P=.05), were more likely to require postoperative pacemaker placement (P<.001), and had higher operative mortality (P<.001) than control patients. Fourteen patients survived the early recovery phase; 9 were followed up at a median of 1.88 years (IQR, 306 days to 3.3 years). All patients' symptoms improved. Median gradient of the left ventricular outflow tract was 13 mm Hg (IQR, 0-15 mm Hg) at follow-up with mild to moderate (1.6) mitral regurgitation. CONCLUSION: Septal myectomy performed after failed ablation improves gradient and provides excellent relief of symptoms but is associated with a higher incidence of morbidity and mortality.