Abstract
Hypertrophic obstructive cardiomyopathy (HOCM) patients exhibit compromised peak exercise capacity (VO2peak). Importantly, severely reduced VO2peak is directly related to increased morbidity and mortality in these patients. Therefore, we sought to determine clinical predictors of VO2peak in HOCM patients. HOCM patients who performed symptom-limited cardiopulmonary exercise testing between 1995 and 2016 were included for analysis. Peak VO2 was reported as absolute peak VO2, indexed to body weight and analyzed as quartiles, with quartile 1 representing the lowest VO2peak. Step-wise regression models using demographic features and clinical and physiologic characteristics were created to determine predictors of HOCM patients with the lowest VO2peak. We included 1177 HOCM patients (age: 53 ± 14 years; BMI: 24 ± 12 kg/m2) with a VO2peak of 18.0 ± 5.6 mL/kg/min. Significant univariate predictors of the lowest VO2peak included age, female sex, New York Health Association (NYHA) class, BMI, left atrial volume index, E/e’, E/A, hemoglobin, N-terminal pro b-type natriuretic peptide (NT-proBNP), and a history of diabetes, hypertension, stroke, atrial fibrillation, or coronary artery disease. Independent predictors of the lowest VO2peak included age (OR, CI: 1.03, 1.02–1.06; p < 0.0001), women (4.66, 2.94–7.47; p = 0.001), a history of diabetes (2.05, 1.17–3.60; p = 0.01), BMI (0.94, 0.92–0.96; p < 0.0001), left atrial volume index (1.07, 1.05–1.21; p = 0.04), E/e’ (1.05, 1.01–1.08; p = 0.004), hemoglobin (0.76, 0.65–0.88; p = 0.0004), and NT-proBNP (1.72, 1.42–2.11; p < 0.0001). These findings demonstrate that demographic factors (i.e., age and sex), comorbidities (e.g., diabetes and obesity), echocardiography indices, and biomarkers (e.g., hemoglobin and NT-proBNP) are predictive of severely compromised VO2peak in HOCM patients.
Highlights
Hypertrophic cardiomyopathy (HCM) is a commonly inherited heart disease affecting 1 in 500 individuals [1], with ~70% of these patients developing the obstructive phenotype, hypertrophic obstructive cardiomyopathy (HOCM) [2]
Independent predictors of the lowest VO2peak included age (OR, confidence intervals (CIs): 1.03, 1.02–1.06; p < 0.0001), women (4.66, 2.94–7.47; p = 0.001), a history of diabetes (2.05, 1.17–3.60; p = 0.01), BMI (0.94, 0.92–0.96; p < 0.0001), left atrial volume index (1.07, 1.05–1.21; p = 0.04), E/e’ (1.05, 1.01–1.08; p = 0.004), hemoglobin (0.76, 0.65–0.88; p = 0.0004), and NT-proBNP (1.72, 1.42–2.11; p < 0.0001). These findings demonstrate that demographic factors, comorbidities, echocardiography indices, and biomarkers are predictive of severely compromised VO2peak in HOCM patients
Cardiopulmonary exercise testing (CPET) is recommended for HCM patients to determine the severity of exercise intolerance, and the responsible mechanisms [7,8]
Summary
Hypertrophic cardiomyopathy (HCM) is a commonly inherited heart disease affecting 1 in 500 individuals [1], with ~70% of these patients developing the obstructive phenotype, hypertrophic obstructive cardiomyopathy (HOCM) [2]. Patients with HOCM have a greater risk of mortality and greater severity of heart failure than HCM patients without obstruction [3]. HCM patients with and without obstruction generally present with exertional dyspnea, fatigue, and reduced peak functional capacity [1]. Reduced peak oxygen consumption (VO2peak) in HCM patients is associated with greater mortality and more severe progression of heart failure [9,10,12,13]. HCM patients exhibit numerous cardiovascular risk factors, including diabetes, arterial hypertension, and coronary artery disease [9,10,11,16,17]. The contribution of these cardiovascular risk factors to the worsening of VO2peak in patients with HOCM is unknown. In the present study we sought to determine the relationship(s) between demographic factors, comorbidities, and echocardiography indices with the compromised VO2peak in HOCM patients
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