Background We have previously reported that heart rate recovery (HRR) after a six-minute walk test (6MWT) is a free and easily measured biomarker that can accurately predict clinical worsening in patients with idiopathic pulmonary arterial hypertension. It is unknown if HRR can predict clinical outcomes in patients with connective tissue diseases.
Objectives We aimed to determine whether abnormal heart rate recovery at one minute of rest (HRR1) after the 6MWT(HRR1 < 16 beats per minute) predicts survival and hospitalization in patients with pulmonary hypertension associated with connective tissue diseases (CTD-PAH).
Methods Patients with pulmonary hypertension and a diagnosis of systemic sclerosis (SSc), systemic lupus erythematosus (SLE), or mixed connective tissue disease (MCTD) who underwent the 6MW test between August 1, 2009 and October 30, 2011 were included in the analysis. Patients on beta-blocker therapy at the time of the 6MW test were excluded.
Results 66 patients with CTD-PAH completed the 6MW test. Compared to patients with HRR1 > 16, patients with HRR1 < 16 were older (58 + 15 years vs. 52 + 16 years; p = 0.001), less likely to be female (75% vs. 97%; p = 0.017), and had worse WHO FC (p = 0.003). Patients with HRR1 < 16 and HRR1 > 16 did not differ significantly in baseline pulmonary function test variables (% predicted FVC, FEV1, and DLCO). Patients with abnormal HRR1 had lower 6MW distance (272.3 + 94.0 meters vs. 367.7 + 103.7 meters; p < 0.001). Patients with abnormal HRR1 had higher incidence of mortality (44% vs. 13%; p = 0.006) and PH-related hospitalizations (49% vs. 13%; p = 0.002). Compared to 6MW distance, HRR1 was a better predictor of PH-related hospitalizations (C-statistic for HRR1 = 0.735 vs. C-statistic for 6MW distance = 0.607).
Conclusions In patients with PH associated with CTD, abnormal HRR1 (defined as HRR1 < 16) after the 6MW test is a strong predictor of survival and hospitalization. HRR1 after the 6MW test is a non-invasive, low cost, and easily obtained measurement that can aid in predicting clinical outcome in patients with PH associated with CTD.
References: Minai OA, Gudavalli R, Mumadi S, Liu X, McCarthy K, Dweik RA. Heart rate recovery predicts clinical worsening in patients with pulmonary arterial hypertension. Am J Respir Crit Care Med 2012;185:400-408
Disclosure of Interest: None Declared