Cardiopulmonary exercise testing: An increasingly important step in managing hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy, the most common genetic heart disease, inherited with an autosomal dominant pattern, incomplete penetrance and variable expressivity, is characterized by markedly heterogeneous morphologic and clinical spectra […]. In such a context, as it is yet worldwide recognized in heart failure with reduced ejection fraction (HFrEF) […], the cardiopulmonary exercise test (CPET) is becoming an essential tool in the contemporary HCM clinical management […]. Indeed, also in this setting of patients, a well-reasoned CPET assessment might be extremely useful to evaluate objectively the true functional capacity […] as well as to better understand mechanisms underlying the exercise impairment [..]. Properly the latter aspect represents one of the most challenging field in the HCM scenario where, besides the disease-related complications, a number of factors have been advocated as possibly implied […], including left ventricular (LV) hypertrophy with myocardial fiber disarray and interstitial fibrosis, LV outflow tract obstruction, microvascular ischemia, chronotropic incompetence, peripheral muscle changes and, in nearly 5% of cases, even LV systolic dysfunction (progression to the “end-stage” phase) (Figure 1). Contextually, growing evidences suggest a possible role of the CPET variables also in stratifying the HCM risk of adverse cardiac events both in terms of sudden cardiac death (SCD) as well as of HF development […], the latter gaining even more in significance in the last decades due to the improvements in pharmacological and no-pharmacological HCM management.