Background: Heart rate recovery (HRR) after exercise correlates with decreased vagal tone and mortality. Patients with COPD may have altered autonomic tone. We sought to determine the association of HRR with spirometry measures of pulmonary function.
Methods: We analyzed 627 patients (mean [± SD] age, 58 ± 12 years; 65% men; mean FEV1, 2.6 ± 0.9 L, 80 ± 20% predicted; patients receiving inhaled β2 agonist therapy, 10%; patients receiving inhaled anticholinergic therapy, 3%; patients receiving inhaled steroids, 5%; patients receiving oral prednisone, 4%) who had undergone maximal exercise testing and had undergone pulmonary function tests < 1 year apart. Patients with heart failure, pacemakers, and atrial fibrillation were excluded. Abnormal HRR was defined as a fall in heart rate during the first minute after exercise of ≤ 12 beats/min (≤ 18 beats/min with stress echocardiography). Patients were divided into quartiles based on FEV1 percent predicted.
Results: An abnormal HRR was seen in 229 patients (36%). The mean FEV1 values broken into quartiles 1 to 4 were 54 ± 11% predicted, 74 ± 3% predicted, 87 ± 4% predicted, and 106 ± 10% predicted. In smokers and nonsmokers, a worsening FEV1 percent predicted was associated with an abnormal HRR. In a multivariable model accounting for confounding factors including medications and functional capacity, the predictors of an abnormal HRR included FEV1 percent predicted (adjusted odds ratio for 1 SD decrease, 1.32; 95% confidence interval, 1.07 to 1.65; p = 0.0004), impaired functional capacity, male gender, and age.
Conclusions: Abnormalities found on spirometry are associated with abnormal HRR, which may reflect an altered autonomic tone associated with pulmonary dysfunction, either obstructive or restrictive in nature.