Syncope in hypertrophic cardiomyopathy (part I): An updated systematic review and meta-analysis

To describe the proportion of patients with syncope among those affected by hypertrophic cardiomyopathy (HCM) and the relevance of syncope as risk factor for sudden cardiac death and life-threatening arrhythmic events. Systematic review of original articles that assessed syncope in HCM patients. Literature search of PubMed including all English publications from 1973 to 2021.We found 57 articles for a total of 21.791 patients; of these, 14 studies reported on arrhythmic events in the follow-up. Syncope was reported in 15.8% (3.452 of 21.791) patients. It was considered unexplained in 91% of cases. Life-threatening arrhythmic events occurred in 3.6% of non-syncopal patients and in 7.7% of syncopal patients during a mean follow-up of 5.6 years. A relative risk of 1.99 (95%CI 1.39 to 2.86) was estimated for syncope patients by the random effect model using Haldane continuity correction for 0 events. In the current practice, the cause of syncope remained unexplained in most patients affected by HCM. The management of patients seems mainly driven by risk stratification rather than identification of the aetiology of syncope. There is a need of precise instructions how to apply the recommendations of current guidelines to this disease, which tests are indicated and how to interpret their findings. The protocol was registered in Prospero (ID: 275963). [Display omitted] •Syncope was reported in 15.8% of patients with hypertrophic cardiomyopathy.•Syncope was considered unexplained in 91% of them.•Arrhythmic events occurred in 3.6% of non-syncopal and in 7.7% of syncopal patients.•The relative risk of arrhythmic events was 1.99 (95%CI 1.39 to 2.86).•There is a need of precise instructions how to diagnose syncope.