Isolated septal myectomy for hypertrophic obstructive cardiomyopathy: an update on the Toronto General Hospital experience

Abstract

Background: Isolated septal myectomy is considered the gold standard for refractory left ventricular outflow tract (LVOT) obstruction at centers with dedicated hypertrophic obstructive cardiomyopathy (HOCM) surgeons. In this paper, we provide an update on the Toronto General Hospital (TGH) experience for isolated septal myectomy and comment on the safety and efficacy of myectomy in patients with thin basal septal thickness at our institution. Methods:We retrospectively reviewed all patients undergoing surgical myectomy at our institution from January 2012 to August 2016. We analyzed patient characteristics, intraoperative variables, pre-and postprocedural echocardiographic parameters, and key outcomes including post-operative stroke, renal failure, iatrogenic ventricular septal defect (VSD), post-procedure insertion of permanent pacemaker, and mortality.Results: At our institution, 150 isolated septal myectomy surgeries were performed over the study period.Preoperative echocardiography demonstrated an average basal septal thickness of 2.10±0.43 cm with a resting gradient of 67±37 mmHg and a provoked gradient of 89±40 mmHg. Fifty percent of patients had significant systolic anterior motion (SAM) of their mitral valve and 53% had associated moderate to severe mitral regurgitation (MR). Of note, 24% of patients had a thin septum of ≤1.7 cm. Discharge echocardiograms demonstrated significant septal reduction to an average basal septal thickness of 1.04±0.26 (P<0.05), with negligible resting and provokable LVOT gradients. At the time of discharge, none of the patients had significant SAM and only 5.3% of patients had residual greater than mild MR. Patients undergoing isolated myectomy with a thin basal septum had similar outcomes to those with a >1.7 cm septal thickness. In our contemporary cohort, there were no iatrogenic VSDs, 5.3% of patients required a permanent pacemaker and there was one early death.Conclusions: Our cohort demonstrates that isolated septal myectomy remains a safe and effective operation that can achieve excellent results, irrespective of basal septal thickness, when done by experienced surgeons in a dedicated hypertrophic cardiomyopathy (HCM) center.

Exercise Echocardiography following Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

“…A study by Vanderlaan et al has shown a complete depletion of SAM, but the proportion of patients with preoperative SAM was lower (50%) than in our study (76%). 18 It has been unclear whether SAM at rest persists during exercise or whether SAM may reappear during exercise. In this study, SAM at rest persisted during exercise.…”

Hypertrophic cardiomyopathy: the future of treatment

“…9,10 Surgical myectomy has demonstrated excellent long-term efficacy and safety at selected high-volume centres with near-complete resolution of resting and inducible LVOT gradients, perioperative mortality rates <1%, and long-term survival similar to demographic-matched controls. 68,69 Nonetheless, it remains a major operation with risks that may be prohibitive or undesirable for certain patients. Moreover, outcomes have been substantially less impressive outside of experienced centres, with an overall mortality of 5.2% in a nationally representative US database.…”

“…Surgical myectomy has demonstrated excellent long‐term efficacy and safety at selected high‐volume centres with near‐complete resolution of resting and inducible LVOT gradients, perioperative mortality rates <1%, and long‐term survival similar to demographic‐matched controls . Nonetheless, it remains a major operation with risks that may be prohibitive or undesirable for certain patients.…”

Closure of an iatrogenic ventricular septal defect using a hybrid approach and echocardiographic guidance

“…The occurrence of VSD following septal myectomy is rare with reported incidence between 0% and 2%. [ 1 ] In these patients, the ventricular septal tissue quality might be poor due to purposeful prior resection and patch repair could be challenging. Peripheral accessed percutaneous VSD closure is a viable alternative to surgery.…”