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Significance of 6-Minute Walk Test in Diastolic HF | Journal Scan
Study Questions:
What are the prognostic significance and clinical determinants of the 6-minute walk test (6-MWT) in patients with pulmonary hypertension associated with diastolic heart failure (HF)?
Methods:
The study authors enrolled patients with pulmonary hypertension associated with diastolic HF from a prospective registry. Pulmonary hypertension was confirmed by right heart catheterization. Primary outcomes included HF hospitalizations and/or mortality due to cardiovascular reasons. Left ventricular (LV) extracellular matrix was quantified using endomyocardial biopsies in 18 patients. The study authors utilized multiple regression models to establish determinants of 6-MWT.
Results:
The study cohort was comprised of 142 consecutive patients (99 women and 43 men, mean age 71 ± 9 years) with pulmonary hypertension and diastolic HF, and who were able to perform the 6-MWT. The mean duration of follow-up was 14 ± 10 months; 30.3% (n = 43) of the patients reached the combined endpoint. The investigators found that 6-MWT was an independent predictor of outcome, and was influenced by several parameters (including clinical, echocardiographic, hemodynamic, laboratory, and pulmonary). There was a correlation between the 6-MWT and mean pulmonary arterial pressure (p < 0.001), pulmonary compliance (p < 0.001), and transpulmonary pressure gradient (p < 0.001). In contrast to pure pre-capillary pulmonary hypertension, no correlation was found between cardiac output and the 6-MWT (p = 0.173). There was a significant negative correlation between 6-MWT and the extent of extracellular matrix in the left ventricular (LV) myocardium (R = –0.501, p =0.034).
Conclusions:
The authors concluded that the 6-MWT may be useful in predicting outcome in patients with pulmonary hypertension associated with diastolic HF.
Perspective:
Despite several determinants of exercise capacity, this study suggests that 6-MWT is an important determinant of outcomes in patients with pulmonary hypertension and diastolic HF. It would have been useful to know how many patients included in this study had associated sleep apnea, which could have independently contributed to pulmonary hypertension. The negative correlation between 6-MWT and extent of LV extracellular matrix involvement is an important finding because it could be a potential therapeutic target. Larger multicenter studies are now needed to establish the important findings of this study.
Keywords: Arterial Pressure, Biopsy, Capillaries, Cardiac Catheterization, Cardiac Output, Cohort Studies, Echocardiography, Exercise Test, Extracellular Matrix, Heart Failure, Heart Failure, Diastolic, Hospitalization, Hypertension, Pulmonary, Prospective Studies, Registries, Walking
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