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Changes in Oxygen Consumption and Heart Rate After Acute Myocardial Infarction During 6‐Month Follow‐up
Author(s) -
Choe Yuri,
Han JaeYoung,
Choi InSung,
Park HyengKyu
Publication year - 2018
Publication title -
pmandr
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.617
H-Index - 66
eISSN - 1934-1563
pISSN - 1934-1482
DOI - 10.1016/j.pmrj.2017.11.015
Subject(s) - medicine , heart rate , ejection fraction , vo2 max , myocardial infarction , cardiology , body mass index , metabolic equivalent , physical therapy , rehabilitation , exercise intensity , heart failure , blood pressure , physical activity
Background Exercise intensity is a particularly important determinant of physiological responses to exercise training in patients with acute myocardial infarction. Heart rate (HR) is commonly used as a practical way of prescribing and monitoring exercise as specific intensities based on a linear relationship between the percentage of maximum HR (%HR max ) and the percentage of maximum oxygen consumption (%VO 2max ) regardless of age, gender, or exercise mode. Objective To examine the change in variability in the correlation between %HR max and %VO 2max after acute myocardial infarction. Design Retrospective study. Setting Regional cardio‐cerebrovascular center at a tertiary hospital. Patients A total of 66 patients were enrolled who were referred for cardiac rehabilitation (CR) after percutaneous intervention, and who had reached stage 3 of the modified Bruce Protocol (mBP) on an exercise tolerance test (ETT). Methods There were 54 men and 12 women with an average age of 56.7 ± 9.48 years, ejection fraction (EF) of 56.4% ± 8.89%, and body mass index (BMI) of 24.73 ± 2.86 kg/m 2 . All patients participated in a 4‐week outpatient CR program and underwent ETT with a gas analyzer to determine maximal heart rate and maximal oxygen consumption before CR and 1 month, 3 months, and 6 months after CR. Main Outcome Measurements VO 2max and HR max were defined as the highest values attained during the ETT. The HR and VO 2 values at each stage of the mBP were expressed as percentages of their maximum. %HR max and %VO 2max were calculated at each stage of the mBP. Results The maximum METs and VO 2max significantly improved at 1 month after CR, but not significantly at 3 and 6 months after CR. The correlation between VO 2max and HR max progressively changed in a favorable manner during CR. The relationship between %HR max and %VO 2max indicated a coefficient of variation before and 1, 3, and 6 months after of 0.800, 0.826, 0.832, and 0.880, respectively. Conclusions This study showed that the %HR max correlates better with the %VO 2max in the late‐stage post‐AMI than in the initial stage. We should therefore set and monitor the exercise intensity using maximal oxygen consumption in the early stage of exercise training after onset of acute myocardial infarction. Level of Evidence IV