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Original research
Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy
  1. Massimo Mapelli1,2,
  2. Simona Romani1,
  3. Damiano Magrì3,
  4. Marco Merlo4,
  5. Marco Cittar4,
  6. Marco Masè4,
  7. Manuela Muratori5,
  8. Giovanna Gallo3,
  9. Matteo Sclafani3,
  10. Cosimo Carriere4,
  11. Denise Zaffalon4,
  12. Elisabetta Salvioni1,
  13. Irene Mattavelli1,
  14. Carlo Vignati1,
  15. Fabiana De Martino1,
  16. Sara Rovai1,
  17. Camillo Autore3,
  18. Gianfranco Sinagra4,
  19. Piergiuseppe Agostoni1,2
  1. 1 Heart Failure Unit, Centro Cardiologico Monzino Istituto di Ricovero e Cura a Carattere Scientifico, Milano, Lombardia, Italy
  2. 2 Department of Clinical Sciences and Community Health, University of Milan, Milano, Italy
  3. 3 Clinical and Molecular Medicine, University of Rome La Sapienza, Rome, Italy
  4. 4 Cardiothoracovascular Department, Center for the Diagnosis and Treatment of Cardiomyopathies, Azienda Sanitaria Universitaria Giuliano Isontina [ASUGI] - University of Trieste, Trieste, Italy
  5. 5 Cardiovascular Imaging, Centro Cardiologico Monzino Istituto di Ricovero e Cura a Carattere Scientifico, Milano, Italy
  1. Correspondence to Professor Piergiuseppe Agostoni, Department of Clinical Sciences and Community Health, University of Milan, Milano 20138, Italy; piergiuseppe.agostoni{at}ccfm.it

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.

  • hypertrophic cardiomyopathy

Data availability statement

Data are available on reasonable request. The raw data of this study will be made public on www.zenodo.org and available for consultation after appropriate request.

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Data availability statement

Data are available on reasonable request. The raw data of this study will be made public on www.zenodo.org and available for consultation after appropriate request.

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Footnotes

  • MM and SR are joint first authors.

  • Contributors Planning of the study: MMap, SRom, PA, DM, GS. Collection of data: MMap, SRom, MMer, MC, MMas, MMur, GG, MS, CC, DZ. Analysis: MMap, SRom. Paper drafting: MMap, SRom, DZ, PA, GS. Revisions: ES, IM, CV, FDM, SRov, CA. Overall guarantor: PA.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.