Sima CA; Lau BC; Taylor CM; van Eeden SF; Reid WD; Sheel AW; Kirkham AR;
Camp PG.

2018 American Academy of
Physical Medicine and Rehabilitation.

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
< .05). The Cohen’s kappa test revealed poor level of agreement between
CIIS and medical records (kappa = 0.165), indicating that prior MI
diagnosis was under-reported in the medical records. Simple and multiple
regression analyses showed that resting heart rate but not chronotropic
response index was positively associated with CIIS in our population (R2 =
0.29, P < .001). CLD patients with a resting heart rate higher than 80
beats/min had approximately 5 times higher odds of having prior MI, as
evidenced by a CIIS >= 20.

CONCLUSIONS: CLD patients entering pulmonary rehabilitation are at risk
of unreported prior MI. Elevated resting heart rate appears to be an
indicator of prior MI in CLD patients; therefore, careful adjustment of
training intensity is recommended under these circumstances.