| 제목 |
Heart Rate Recovery after Cardiac Rehabilitation in Patients with Low Ejection fraction |
| 소속 |
Dong-A University College of Medicine, and Regional Cardiocerebrovascular Center, Busan, Korea, Department of Physical Medicine and Rehabilitation1 |
| 저자 |
Sang Beom Kim1, Kyeong Woo Lee1, Jong Hwa Lee1†, Min-Gu Kang1, Min Woo Hong1* |
Introduction: Heart rate recovery (HRR) is defined as the rate at which heart rate (HR) decrease within the following minutes after cessation of physical exercise and is non-invasive assessment tool of autonomic cardiac dysfunction. It has been implicated with risk of cardiovascular events and mortality. Thus, it is widely used as a guide to monitor changes in training status. And several studies showed cardiac rehabilitation (CR) improved HRR in the patients with various heart diseases.
Objectives: To evaluate the effects of hospital-based CR on HRR according to the ejection fraction (EF) after acute myocardial infarction (AMI).
Method: We retrospectively reviewed the medical records of the AMI patients who received hospital-based CR from 2016 to 2020. Forty-eight patients were recruited. Patients were divided into three groups according to EF. Patients with EF 50% and over were allocated to mildly decreased EF group (Group A), patients with EF 40% to 49% to moderately decreased EF group (Group B) and patients with EF under 40% were to severely decreased EF group (Group C). All patients underwent an exercise tolerance test (ETT) 2 weeks after AMI. Second ETT was conducted 3 months after AMI. After achieving a peak workload, cool-down period was followed in which patients kept walking slowly. HRR was defined as the difference between maximal HR and HR measured at 1-minute after starting cool-down period. All patients underwent hospital-based CR twice a week for 2 months. Each session lasted for 40 minutes according to target submaximal heart rate, as calculated by Karvonen method.
Results: At 1st ETT, HRR of Group C was the lowest among the three groups and there was no significant difference between Group A and Group B. At 2nd ETT, HRR of Group C was the lowest among the three groups and there was no significant difference between Group A and Group B. All groups showed improvements of HRR after CR. When the therapeutic effect was compared between three groups, Group A and Group B showed more improvement in HRR than Group C significantly. There was no significant difference between Group A and Group B.
Conclusion: There was therapeutic effect of CR in HRR after hospital-based CR in all groups. Severely decreased EF group showed lesser improvement of HRR than the others. Different therapeutic approach should be considered for patients with such characteristics. |
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Table 1. Baseline characteristics
Table 2. HRR values at 1st and 2nd ETT and the difference of HRR between 1st and 2nd ETT
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