Systematic Review and Meta-Analysis Comparing Long-Term Outcomes in Apical Versus Nonapical Hypertrophic Cardiomyopathy.

Hypertrophic Cardiomyopathy (HCM) is the most common inherited cardiomyopathy that causes Sudden Cardiac Death (SCD). Apical HCM (ApHCM) tends to be more benign than other phenotypes of HCM. However, recent data showed the rate of adverse outcomes of ApHCM is increasing. We aim to compare the long-term outcome of ApHCM with non-ApHCM patients. We extracted data from PubMed, ScienceDirect and Cochrane Library using the keywords "apical hypertrophic cardiomyopathy", "nonapical hypertrophic cardiomyopathy", and "septal hypertrophic cardiomyopathy". Inclusion criteria include cohort studies comparing ApHCM with non-ApHCM. The endpoints were clinical, arrhythmia-related, and heart failure-related outcomes. Study quality assessed by Newcastle-Ottawa Scale (NOS). We present data as Odds Ratio (OR) for dichotomous and Mean Differences (MD) for continuous data. From 6 included cohort studies (8,179 patients), the risk of MACE was lower in ApHCM compared to the non-ApHCM group (OR = 0.48, 95% CI = 0.40-0.59, p <0.00001). The risk of all-cause mortality was also lower in the ApHCM group (OR = 0.44, 95% CI = 0.30-0.63, p <0.0001). We found no difference in the risk of SCD and sustained monomorphic VT. A similar result was also found in heart-failure endpoints. However, apical aneurysm is more common in ApHCM. All included studies were considered good quality by NOS. In conclusion, our study suggests a more benign clinical course of ApHCM compared to non-ApHCM patients. The phenotypic identification of each HCM patient is essential to stratify the prognosis and lead to better management strategies.