OBJECTIVES: To systematically identify studies evaluating the efficacy and safety of pharmacological interventions and septal reduction therapies (SRT) used to treat obstructive hypertrophic cardiomyopathy (HCM).

METHODS: Embase®, MEDLINE® and MEDLINE® In-Process (via ProQuest), the Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews were searched from database inception until 3 December 2021. Randomised controlled trials (RCT), non-randomised and observational studies evaluating the efficacy and safety of pharmacological and SRT treatments for adults with obstructive HCM were eligible for inclusion. Grey literature was searched from 2019 until the same date. Study selection was conducted by two independent reviewers and data extractions were quality assured.

RESULTS: 1,742 records were identified, and 191 studies met the inclusion criteria: 4 RCTs (3 evaluating pharmaceutical interventions, 1 SRT) and 187 non-randomised/observational studies (18 evaluating pharmacological interventions, 169 SRT). Of the 187 non-randomised and observational studies identified, studies were either prospective, retrospective, comparative or single-arm studies. Data pertaining to mavacamten, calcium-channel blockers, beta-blockers, disopyramide, and cibenzoline were found. Apart from a mavacamten study (EXPLORER-HCM), the RCTs were small (N= ≤76) and assessed as either low or indeterminable quality. The most commonly reported RCT outcomes were changes in left ventricular outflow gradients and NYHA class. Limited safety information was available. Studies evaluating SRT were frequently deemed of low or indeterminable quality and largely heterogenous, varying in study design, intervention technique, operator experience, geographical locations and often evaluated procedures conducted more than 15 years ago. Adverse events related to SRT were infrequently reported.

CONCLUSIONS: There is a paucity of good quality data investigating the absolute and relative efficacy and safety of pharmacological interventions. Data pertaining to SRT were heterogeneous, often of low quality, and should be interpreted with caution. More robust research reflecting current treatment paradigms for obstructive HCM is needed.