PURPOSE: Reduced heart rate recovery (HRR) after exercise has been associated with poor long-term outcomes in patients with cardiac and pulmonary disorders. The current study sought to compare HRR after a six-minute walk test (6MWT) in patients with pulmonary arterial hypertension (PAH) and patients without significant cardiac or pulmonary disease.
METHODS: All patients undergoing 6MWT at out institution also undergo assessment of HRR at 1-minute after exercise. Between August 1, 2009 and March 30, 2010, 106 consecutive patients with PAH (74 with idiopathic PAH and 32 with scleroderma associated PAH) underwent 6MWT. A group of 31 consecutive patients without significant cardiac or pulmonary disease was identified as the control group. Data regarding demographics, pulmonary function parameters, echocardiography, 6MWT, and HRR at 1-minute (HRR1) after 6MWT were collected. Results are described as mean ± standard deviation or median (CI) unless otherwise specified.
RESULTS: Patients in the PAH group (N=106) were 52±15.5 years old and had body mass index of 28±7 kg/m2, forced vital capacity (FVC) of 79±20 % predicted, Right ventricular systolic pressure (RVSP) 76±29 mmHg, and forced expiatory volume in 1 second (FEV1) of 74±21 % predicted. Patients in the control group (N=31) were 54±15 years old and had body mass index of 26.5 kg/m2, FVC 96±16 % predicted, RVSP 28±6 mmHg, and FEV1 of 94±17 % predicted. Compared to the control group, patients with PAH had significantly lower 6MW distance (495±80 vs 381±114 meters; p=<0.001), lower peak heart rate after 6MWT (108±16 vs 84±15; p=<0.001), and lower median HRR1 [25(19-30) vs 17(9-26); p=<0.05].
CONCLUSIONS: HRR at 1-minute is significantly reduced among patients with PAH compared with a control population without evidence of significant underlying cardiac or pulmonary disease.
CLINICAL IMPLICATIONS: Heart rate recovery at 1 minute may be a non-invasive indicator of poor cardio-pulmonary reserve in patients with PAH.
DISCLOSURE: The following authors have nothing to disclose: Qamar Iqbal, Raed Dweik, Kevin McCarthy, R. Gudavalli, S. Mummadi, Omar Minai
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