Chronotropic Intolerance In Patients With Chronic Lyme Disease Identified By Serial Cardiopulmonary Exercise Testing

Document Type

Conference Presentation

Department

Health, Exercise, and Sport Sciences Department

Conference Title

American College of Sports Medicine - Medicine & Science in Sports & Exercise conference

Organization

American College of Sports Medicine

Location

San Francisco, CA

Date of Presentation

5-28-2020

Journal Publication

Medicine & Science in Sports & Exercise

ISSN

0195-9131

DOI

10.1249/01.mss.0000681232.98776.79

Volume

52

Issue

7S

First Page

637

Abstract

In the U.S., annual incidence of Lyme disease is approximately 300,000. In an estimated 5-30% of cases, post-treatment Lyme disease syndrome (PTLDS) develops; symptoms include post-exertional malaise characteristic of myalgic encephalomyelitis. The contribution of autonomic regulation has not been elucidated. PURPOSE: To evaluate cardiovascular responses to serial cardiopulmonary testing in patients with PTLDS. METHODS: 14 patients with PTLDS and 8 sedentary controls underwent 2 maximal exercise tests separated by 24 hours. Heart rate (HR) was measured continuously via electrocardiogram. Expired air was collected for determination of anaerobic threshold (AT) using V-slope methodology and maximal exertion was defined as a respiratory exchange ratio >1.09. Independent-samples t-tests compared baseline characteristics of PTLDS patients and controls. Linear regression determined the effect of PTLDS diagnosis on HR at AT and peak holding workload constant. RESULTS: Patients were 44.0±10.1 years old, weighed 69.8±16.2 kg, and achieved a peak VO2 of 23.8±6.2 mL/kg/min during test 1. HR was 116.2±21.8 bpm at AT and 162.6±25.1 at peak. PTLDS and controls did not differ in peak VO2 during test 1 (p=0.161), test 2 (p=0.134), or the difference between test 1 and test 2 (p=0.498). HR at AT was comparable in test 1 (p=0.127) but different in test 2 (p<0.001). HR at peak was different in test 1 (p=0.001) and test 2 (p<0.001). During test 1, holding workload constant, PTLDS patients had lower peak HR by 19.5 bpm (p=0.033; 95% CI: -37.3 to -1.8). During test 2, holding workload constant, PTLDS predicted a lower HR by 26.8 bpm at AT (p=0.004; 95% CI: -43.9 to -9.8) and 24.3 bpm at peak (p=0.007; 95% CI: -40.9±-7.7). CONCLUSIONS: Patients with PTLDS demonstrated abnormal cardiovascular responses to exercise. Despite accomplishing the same VO2, and holding workload constant, the HR response was diminished in the post-exertional state, potentially indicating dysautonomia in PTLDS.

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