Myocardial Infarction Injury in Patients with Chronic Lung Disease Entering Pulmonary Rehabilitation: Frequency and Association with Heart Rate Parameters

Abstract Background Myocardial infarction (MI) remains under-recognized in chronic lung disease (CLD) patients. Rehabilitation health professionals need accessible clinical measurements to identify the presence of prior MI in order to determine appropriate training prescription. Objectives To estimate prior MI in CLD patients entering a pulmonary rehabilitation program, as well as its association with heart rate parameters such as resting heart rate and chronotropic response index. Design Retrospective cohort design. Setting Pulmonary rehabilitation outpatient clinic in a tertiary care university-affiliated hospital. Patients Eighty-five CLD patients were studied. Methods Electrocardiograms at rest and peak cardiopulmonary exercise testing, performed before pulmonary rehabilitation, were analyzed. Electrocardiographic evidence of prior MI, quantified by the Cardiac Infarction Injury Score (CIIS), was contrasted with reported myocardial events and then correlated with resting heart rate and chronotropic response index parameters. Main outcome measurements CIIS, resting heart rate, and chronotropic response index. Results Sixteen CLD patients (19%) demonstrated electrocardiographic evidence of prior MI, but less than half (8%) had a reported MI history ( P R 2 = 0.29, P Conclusions CLD patients entering pulmonary rehabilitation are at risk of unreported prior MI. Elevated resting heart rate seems to be an indicator of prior MI in CLD patients; therefore, careful adjustment of training intensity such as intermittent training is recommended under these circumstances. Level of evidence III