PURPOSE: Attenuated heart rate recovery (HRR) after exercise testing is associated with increased mortality. The purpose of this study was to evaluate early HRR after 6-minute walk test (6MWT) and the association between abnormal HRR and prognostic markers (WHO class, RV function, DLCO, 6MWD etc) in patients with idiopathic and heritable pulmonary arterial hypertension (Group 1.1 & 1.2).
METHODS: Heart rate at 1 minute post 6MWT was collected routinely at our institute from August 2009. Demographic, clinical, hemodynamic, pulmonary function test and 6MWT variables were collected in patients who had PAH (Group 1.1 & 1.2) and had a 6MWT from August 2009 to March 2010. HRR1 was defined as the difference in the heart rate at the end of 6MWT and at one minute after completion of the 6MWT.
RESULTS: 1444 patients underwent 6MWT from August 2009 to March 2010. 75 patients had a diagnosis of PAH (Group 1.1 & 1.2) and were included in the final analysis. In our cohort of PAH patients, the mean age was 49.13 years, mean mPAP was 52.25 mm Hg, mean plasma BNP was 177.1 pg/ml, mean eRVSP based on transthoracic echocardiogram (TTE) was 80.69 mmHg, mean 6MWD was 440.6 meters, mean HRR1 was 21.29 bpm. HRR1 had a significant negative correlation with age (r= -0.37), RVSP (r= -0.30), and BNP levels (r= -0.61). HRR1 had a significant positive correlation with DLCO (r=0.34) and 6MWD (r=0.58). HRR1 was significantly lower in patients with WHO class III/IV symptoms, elevated BNP levels, and moderate to severe RV dysfunction on TTE. Patients with a lower HRR1 (≤ 15) had a higher risk of hospitalization.
CONCLUSION: HRR1 after 6 MWT correlates with several prognostic markers in PAH (Group 1.1 & 1.2) patients. HRR1 after 6MWT was significantly lower in patients with WHO class III/IV symptoms, moderate to severe RV dysfunction on TTE, and elevated BNP levels.
CLINICAL IMPLICATIONS: HRR1 after 6MWT may reflect disease severity in PAH (Group 1.1 & 1.2) patients.
DISCLOSURE: Ravindra Gudavalli, No Financial Disclosure Information; No Product/Research Disclosure Information