Abnormal Heart Rate Recovery and Chronotropic Incompetence With Exercise in Patients With Interstitial Lung Disease...

Introduction Chronotropic incompetence (CI) and heart rate (HR) recovery at one minute post-exercise (HRR1) have been proposed as indicators of autonomic imbalance. We retrospectively studied the presence of CI and HRR1 attained on cardiopulmonary exercise testing (CPET) in patients with interstitial lung disease (ILD) and those with interstitial lung disease with pulmonary hypertension (ILD-PHTN). Methods A total of 32 patients (21 had ILD alone; 11 had ILD-PHTN) underwent CPET performed per American Thoracic Society protocol on a manually-braked bicycle. HRR1 was defined as the difference between peak HR and HR after one minute post-exercise. The utilization of HR reserve recovery at peak exercise was expressed as Chronotropic Response Index (CRI) and was calculated as (peak HR-resting HR)/(220-age-resting HR). CI was defined by failure to reach 85% of the age-predicted maximum heart rate (APMHR = 200-Age) and CRI<0.80 (80%). Results VO₂max was lower in patients with ILD-PHTN compared to ILD alone (14.15± 5.00 vs. 18.11± 4.48, p<0.05). Mean CRI (0.468± 0.179 versus 0.691± 0.210, p<0.05) and HRR1 (10± 7 versus 18± 9, p<0.05) were lower in patients with ILD-PHTN compared to ILD alone. Twenty out of a total of 32 patients (62.5%) met the criteria for CI. In the ILD group, 10 out of 21 patients (47.62%) and in the ILD-PHTN group 10 of 11 patients (90.90%) had CI. Conclusion Chronotropic Incompetence and abnormal heart rate recovery at one minute post-exercise are notable in patients with ILD and are more severe in patients with ILD-PHTN. These findings may contribute to our understanding of dyspnea due to these conditions.