Predictors of exercise capacity following septal myectomy in patients with hypertrophic cardiomyopathy

Abstract

Aims Patients with hypertrophic obstructive cardiomyopathy (HOCM) have impaired exercise capacity. The gold standard therapy for patients with HOCM is septal myectomy surgery; however, changes in maximum oxygen uptake (VO2peak) following myectomy are variable, with VO2peak decreasing in some patients. Therefore, we evaluated changes in VO2peak following surgical myectomy to determine clinical predictors of those exhibiting decreased VO2peak post-myectomy. Methods HOCM patients ( N = 295) who performed symptom limited cardiopulmonary exercise testing prior to and following surgical myectomy were included for analysis. The VO2peak non-responder group ( n = 128) was defined as <0% change in VO2peak from pre- to post-myectomy. Step-wise regression models using demographics, clinical, and physiologic characteristics were created to determine predictors of hypertrophic cardiomyopathy patients in the VO2peak non-responder group. Results Independent predictors of the VO2peak non-responder group included higher pre-myectomy VO2peak (% predicted), older age, women, history of dyslipidemia, lack of cardiac rehabilitation enrollment, and lower body mass index (all p < 0.03). Forty-three (14.6%) patients reached the primary end-point of all-cause mortality during a median follow up of 11.25 years (interquartile range 6.94 to 16.40). After adjustment for age, sex, beta-blocker use, coronary artery disease history, and body mass index, the VO2peak non-responder group had greater risk of death compared with the VO2peak responder group (adjusted hazard ratio: 1.77, 95% confidence interval: 1.06–3.34, p = 0.01). Conclusion This large hypertrophic cardiomyopathy cohort demonstrated that demographic (i.e. female sex), lack of cardiac rehabilitation enrollment, and cardiovascular risk factors (i.e. history of dyslipidemia) are predictive of those patients that did not exhibit increases in VO2peak following septal myectomy surgery.

Exercise in hypertrophic cardiomyopathy: towards a personalised approach

“…In a large HCM cohort, lack of cardiac rehabilitation enrolment and cardiovascular risk factors were predictive of non-improvement of exercise capacity following septal myectomy surgery. 20 While it seems reasonable to believe that moderate and high-intensity aerobic exercise is safe and efficacious for carefully selected HCM subtypes, so far only one randomised and one non-randomised clinical trial have investigated moderate-intensity aerobic exercise in HCM patients, and a pilot study on highintensity exercise is on its way. 6,7 All studies are small and focus on cardiorespiratory fitness and cardiac morphology and function.…”

Exercise capacity and septal myectomy in hypertrophic cardiomyopthy: Predicting clinical response

“…10 It is therefore not surprising to discover that they were less likely to respond to SM than their male counterparts. 7 The higher peak VO 2 observed among the non-responders probably reflects the fact that these patients were less symptomatic and hence more unlikely to demonstrate an improvement in exercise capacity. The relationship between lower BMI and non-response is intriguing and more difficult to explain.…”

“…present the results of a single centre retrospective analysis of 295 (mean age 50 ± 14 years; 56% men) out of total of 1177 adult patients who underwent SM for HCM between 1996 and 2016. 7 This represented all of the HCM patients in their SM cohort who had undergone a CPET both preceeding and within 6 months of their operation. Overall, 167 patients (56.6%) demonstrated an improvement in their peak oxygen consumption (VO 2 ) and were classed as responders, with the remainder being non-responders.…”

“…How do we interpret the findings of this interesting study? 7 Many of the factors that have been linked to reduced exercise capacity and peak VO 2 with HCM are also known to be related to increased mortality and adverse outcomes following SM. These include older age, female sex, significant comorbidities (e.g.…”

“…The relationship between lower BMI and non-response is intriguing and more difficult to explain. 7 In a recent observational study on 3282 HCM patients observed over a median follow-up of 6.8 years, Fumagalli et al. noted that obesity (31.7% of the cohort) was linked to an increased likelihood of obstructive physiology and adverse outcomes.…”