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. 2022 Sep 26;108(20):1629-1636.
doi: 10.1136/heartjnl-2021-320569.

Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy

Massimo Mapelli  1   2 , Simona Romani  1 , Damiano Magrì  3 , Marco Merlo  4 , Marco Cittar  4 , Marco Masè  4 , Manuela Muratori  5 , Giovanna Gallo  3 , Matteo Sclafani  3 , Cosimo Carriere  4 , Denise Zaffalon  4 , Elisabetta Salvioni  1 , Irene Mattavelli  1 , Carlo Vignati  1 , Fabiana De Martino  1 , Sara Rovai  1 , Camillo Autore  3 , Gianfranco Sinagra  4 , Piergiuseppe Agostoni  6   2
Affiliations
Free article

Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy

Massimo Mapelli et al. Heart. .
Free article

Abstract

Objectives: Reduced cardiac output (CO) has been considered crucial in symptoms' genesis in hypertrophic cardiomyopathy (HCM). Absolute value and temporal behaviour of O2-pulse (oxygen uptake/heart rate (VO2/HR)), and the VO2/work relationship during exercise reflect closely stroke volume (SV) and CO changes, respectively. We hypothesise that adding O2-pulse absolute value and kinetics, and VO2/work relationship to standard cardiopulmonary exercise testing (CPET) could help identify more exercise-limited patients with HCM.

Methods: CPETs were performed in 3 HCM dedicated clinical units. We retrospectively enrolled non-end-stage consecutive patients with HCM, grouped according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva manoeuvre (72% of patients with LVOTO <30; 10% between 30 and 49 and 18% ≥50 mm Hg). We evaluated the CPET response in HCM focusing on parameters strongly associated with SV and CO, such as O2-pulse and VO2, respectively, considering their absolute values and temporal behaviour during exercise.

Results: We included 312 patients (70% males, age 49±18 years). Peak VO2 (percentage of predicted), O2-pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety-six (31%) patients with HCM presented an abnormal O2-pulse temporal behaviour, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs 130±49 W), VO2 (21.3±6.6 vs 24.1±7.7 mL/min/kg; 74%±17% vs 80%±20%) and O2-pulse (12 (9-14) vs 14 (11-17) mL/beat), with higher VE/VCO2 slope (28 (25-31) vs 27 (24-31)) (p<0.005 for all). Only 2 patients had an abnormal VO2/work slope.

Conclusion: None of the frequently used CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal temporal behaviour of O2-pulse during exercise, which is strongly related to inadequate SV increase, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, identifying more advanced disease irrespectively of LVOTO.

Keywords: hypertrophic cardiomyopathy.

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Conflict of interest statement

Competing interests: None declared.