Clinical Profile of Nonresponders to Surgical Myectomy with Obstructive Hypertrophic Cardiomyopathy

Background: Surgical myectomy reverses heart failure symptoms in the vast majority of obstructive hypertrophic cardiomyopathy patients. However, a small subgroup fails to experience sustained postoperative improvement despite relief of obstruction. Clinical profile of such patients has not been well defined.

Methods: Consecutive obstructive hypertrophic cardiomyopathy patients undergoing myectomy at Tufts Medical Center for drug-refractory New York Heart Association III/IV heart failure symptoms, 2004 to 2017, were followed postoperatively for 2.5 ± 2.8 years and assessed for outcome.

Results: Of the 503 patients, there were 4 postoperative deaths (0.8%); 480 patients (96%) had sustained improvement to New York Heart Association classes I or II (responders), but 19 (3.8%) developed advanced symptoms (classes III or IV) in the absence of obstruction (nonresponders). Compared with responders, nonresponders were younger (40 ± 13 vs 53 ± 14 years; P < .001) and had greater septal thickness (25 ± 9 vs 20 ± 4 mm; P < .001). Massive hypertrophy (≥30 mm) was 5-fold more common in nonresponders (P < .01). Seven nonresponders developed systolic dysfunction (ejection fraction 20%-47%), 2 days to 6.1 years postoperatively. Four nonresponders underwent heart transplant 3.4 to 9.2 years after myectomy, and 2 others have been listed.

Conclusions: Surgical myectomy is highly effective at reversing heart failure symptoms in the vast majority of patients with obstructive hypertrophic cardiomyopathy. However, a small minority experience persistent functional limitation despite surgical relief of outflow obstruction. Predictors of adverse postoperative course were substantial/massive septal thickness and youthful age. Patients who failed to respond symptomatically to myectomy were considered for advanced heart failure treatment, including heart transplantation.