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J Heart Lung Transplant. 2015 Nov;34(11):1430-5. doi: 10.1016/j.healun.2015.05.016. Epub 2015 Jun 10.

Ventilatory gas exchange and early response to cardiac resynchronization therapy.

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Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota. Electronic address:
Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota.
Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona.



Cardiac resynchronization therapy (CRT) is an accepted intervention for chronic heart failure (HF), although approximately 30% of patients are non-responders. The purpose of this study was to determine whether exercise respiratory gas exchange obtained before CRT implantation predicts early response to CRT.


Before CRT implantation, patients were assigned to either a mild-moderate group (Mod G, n = 33, age 67 ± 10 years) or a moderate-severe group (Sev G, n = 31, age 67 ± 10 years), based on abnormalities in exercise gas exchange. Severity of impaired gas exchange was based on a score from the measures of VE/VCO(2) slope, resting PETCO(2) and change of PETCO(2) from resting to peak. All measurements were performed before and 3 to 4 months after CRT implantation.


Although Mod G did not have improved gas exchange (p > 0.05), Sev G improved significantly (p < 0.05) post-CRT. In addition, Mod G did not show improved right ventricular systolic pressure (RSVP; pre vs post: 37 ± 14 vs 36 ± 11 mm Hg, p > 0.05), yet Sev G showed significantly improved RVSP, by 23% (50 ± 14 vs 42 ± 12 mm Hg, p < 0.05). Both groups had improved left ventricular ejection fraction (p < 0.05), New York Heart Association class (p < 0.05) and quality of life (p < 0.05), but no significant differences were observed between groups (p > 0.05). No significant changes were observed in brain natriuretic peptide in either group post-CRT.


Based on pre-CRT implantation ventilatory gas exchange, subjects with the most impaired values appeared to have more improvement post-CRT, possibly associated with a decrease in RVSP.


exercise; heart failure; pulmonary hypertension; right ventricle pressure; ventilatory efficiency

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