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Effects of cardiac rehabilitation on cardiovascular disease

Exercise-based CR is a crucial part of secondary prevention for patients after coronary artery bypass grafting. Yet little is known about the dose— response relationship. Retrospective cohort study Methods: We investigated whether a dose—response relationship existed among CR attendance, exercise intensity progress proportion EIPPand the short-term event-free rate.

The outcome in the 6-year follow-up was the events free rate of cardiovascular events. The event-free survival rate was 59. The event-free survival rate was 57. CR is associated with more favorable outcomes in CAD patients. Our results support national policy that CR is recommended for CABG, and recommended exercise dose for clinical prescription.

Keywords Secondary prevention; Coronary artery disease; Coronary artery bypass surgery; Cardiac rehabilitation Introduction Atherosclerosis-related coronary heart disease CHD has remained the leading cause of death globally for the past 40 years, accounting for one-third of all-cause mortality deaths, and its incidence is increasing by the each year in Taiwan [ 12 ]. Effective interventions that facilitate slowing CHD progression are essential and must be applied where appropriate. Secondary prevention can control risk factors and reduce the degree of restenosis and mortality [ 6 - 9 ].

Lack of appropriate secondary prevention may lead to cardiac problems, requiring another invasive intervention.

  • Exercise-based CR is a crucial part of secondary prevention;
  • Survival was described using the event-free rate;
  • Keywords Secondary prevention; Coronary artery disease; Coronary artery bypass surgery; Cardiac rehabilitation Introduction Atherosclerosis-related coronary heart disease CHD has remained the leading cause of death globally for the past 40 years, accounting for one-third of all-cause mortality deaths, and its incidence is increasing by the each year in Taiwan [ 1 , 2 ].

Exercise-based CR is a crucial part of secondary prevention. CR can reduce risk factors and improve exercise capacity and survival after percutaneous coronary intervention PCI and coronary artery bypass grafting CABG.

Furthermore, CR can enhance peak VO2; alleviate dyspnea or fatigue symptoms; improve oxygen utilization and quality of life; and reduce sympathetic tone [ 89 ]. Adherence to CR may influence the survival benefits associated with CR.

  • All of these studies assessed the relationship between the number of exercise sessions attended and the mortality or event-free rate [ 6 , 9 , 23 ];
  • Acknowledgments The authors thank Yu-Jen Wang for data collection, and all the studied subjects for their consents to join the study;
  • These findings support the U;
  • To describe the event-free rate of the study population, we plotted cumulative incidence estimates by using a single Kaplan—Meier curve for all patients and separate Kaplan— Meier curves for patients in the CRG and NCRG;
  • We speculate that the number of CR sessions might not affect the results.

Studies have investigated the relationship between CR attendance and mortality, but the findings are mixed. In Sweden, CR attendance was associated with reduced mortality after 10 years but not after 5 years [ 1011 ]. In a study on 846 CABG patients who received CR after surgery, a strong relationship was observed between CR attendance and longterm mortality reduction [ 8 ]. Several studies have reported that conditions such as traffic and work were the main reasons for poor attendance to an exercisebased CR program.

Thus, programs that require minimum attendance and an enhanced exercise intensity progression proportion EIPP are essential for patients to undertake home-based exercise at an early stage, thus facilitating exercise regularity and promoting secondary prevention.

In this 6-year follow-up study, we examined the relationship between CR attendance and the cardiovascular event-free rate after CABG.

Furthermore, we investigated whether a dose— response relationship existed among CR attendance, exercise intensity, and the short-term event-free rate.

Methods Study population In this retrospective cohort study, we evaluated the shortterm event-free rate of patients after CABG. We included 266 patients 205 men, 78.

  1. Patients who were not followed up in the outpatient department of CHGH were considered alive, and the last date of follow-up was obtained.
  2. In Sweden, CR attendance was associated with reduced mortality after 10 years but not after 5 years [ 10 , 11 ]. Second, patients with no record of death on the charts indicated as alive were ultimately censored on December 31, 2014.
  3. No significant difference was observed in the event-free rate between the 2 groups 66.
  4. The outcome in the 6-year follow-up was the events free rate of cardiovascular events.

To evaluate disease severity and avoid survival bias, we excluded 5 patients who died during hospitalization. All patients were encouraged to attend the CR program and retrospectively followed up for 6 years to determine their CR attendance and acute event incidence.

All participants signed informed consent form before inclusion. Most patients underwent a graded exercise test at the baseline as part of an exercise prescription.

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They were prescribed exercise for 20—40 minutes 3 times per week. The training program comprised warm-up, training, and cool-down phases. The training intensity depended on the anaerobic threshold AT obtained through the submaximal symptom-limited exercise test.

If the patients did not achieve the AT, the peak VO2 was considered the training target.

Furthermore, they did not receive any personal exercise consultations. The CR attendance rate was calculated as the number of sessions attended in 3 months divided by the number of CR sessions available in 3 months. The exercise intensity progression proportion was determined according to the proportion of the difference between the peak intensities achieved in the first and last sessions divided by the peak intensity achieved in the first session.

The peak VO2 was derived from an exercise pulmonary function test EPFT using a modified Bruce protocol or a stationary bike ramp protocol. Endpoints outcomes The primary outcome in the 6-year follow-up was the incidence of cardiovascular events, such as death, which was ascertained using a 2-stage approach. First, the vital status of the patients was extracted from the CHGH registration database. Second, patients with no record of death on the charts indicated as alive were ultimately censored on December 31, 2014.

Patients who were not followed up in the outpatient department of CHGH were considered alive, and the last date of follow-up was obtained. The number of patients who developed cardiac events, including death and nonfatal MI, and underwent repeat CABG or percutaneous transluminal coronary angioplasty was identified, and the time to the first cardiac event was calculated.

Statistical Analysis Baseline basic and clinical data are reported as means or proportions. Survival was described using the event-free rate. To describe the event-free rate of the study population, we plotted cumulative incidence estimates by using a single Kaplan—Meier curve for all patients and separate Effects of cardiac rehabilitation on cardiovascular disease Meier curves for patients in the CRG and NCRG.

We evaluated the differences between the separate curves by using the logrank test. For these analyses, the time at risk began on an event date and ended on the date of death or December 31, 2014. To assess the relationship between the attendance and event-free rates, we constructed survival models. A 2-sided P value of. To assess the relationship between the exercise intensity progression proportion EIPP and the event-free rate, we constructed additional survival models. Five of the 266 patients who died during hospitalization were excluded, and the remaining 261 patients were enrolled.

Basic demographic and clinical characteristics are listed in Table 1. The demographic data did not differ significantly between the 2 groups, except for age, ischemic time, and pumping time Table 1. The mean follow-up period was 64. Data are presented as mean SD or No. Diabetes Mellitus, Hos duration, duration of hospital stay. The mean number of CR sessions effects of cardiac rehabilitation on cardiovascular disease 13. The event-free survival curves for 6 years revealed that the event-free rate was 59.

The event-free survival rates were not significantly different between the 2 groups of the CRG, but they were significantly higher than those of the NCRG event-free rate: These patients were exclude for EIPP calculation. We divided the CRG into 2 subgroups as follows: No significant difference was observed in the event-free rate between the 2 groups 66.

Discussion Previous studies have suggested that CR is associated with more favorable outcomes in CAD patients, and clinical trials have suggested that CR is beneficial to health [ 691012 - 15 ]. In our study, we extended the findings of previous studies by examining a cohort of CABG patients, using the suggested proportion of exercise intensity progression between the first and last CR sessions, assessing both the event-free rate and EIPP, and exploring the relationship between CR patterns and the event-free rate.

In our study, the CRG was associated with a higher eventfree rate than that of the NCRG, which is consistent with the findings of previous studies [ 689 ]. The CRG patients were strongly encouraged to lead an active lifestyle and received intensive supervised exercise training.

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On average, the CRG patients joined 13. Physical training may reduce mortality and morbidity in CAD patients [ 6 ] Table 2. These findings support the U. A few studies have investigated the exercise dose—response relationship. All of these studies assessed the relationship between the number of exercise sessions attended and the mortality or event-free rate [ 6923 ].

However, regarding clinical implications, functional performance was associated with exercise intensity. Exercise training can significantly improve peak oxygen consumption, the exercise duration, the resting heart rate, and quality of life. Our study was the first to investigate the relationship between EIPP and the event-free rate. In this study on post-CABG patients who did and did not participate in CR, we observed no significant dose—response relationship.

No significant difference in the event-free rate was observed for the 2 CR attendance groups, but the eventfree rate in the CRG was significantly higher than that in the NCRG during the 6-year follow-up.

What is Cardiac Rehabilitation?

We speculate that the number of CR sessions might not affect the results. Evidence on the dose—response relationship between CR and event-free survival rate among patients with CHD is mixed.

Most authors have reported benefits associated with an increasing number of CR sessions and a dose response to exercise [ 9101215 - 23 ]. Our study strongly supports the notion that CR participation reduces the event-free rate.

However, this study was limited by several factors. Second, a potential for bias exists because of the unmeasured underlying health statuses of patients. In addition, there may be residual confounding by the health status even among these patients, although the direction in which the health status may bias the results is unclear. Healthier patients may not feel motivated to attend CR and may be likely to attend fewer sessions than other patients do.

Furthermore, less healthy patients cannot tolerate CR and thus may attend fewer sessions than their healthy counterparts do. Third, patients might be lost to follow-up at the original hospital, and hence the primary endpoint may be lost. However, our research assistant made specific phone calls to follow up with the patients.

Acknowledgments The authors thank Yu-Jen Wang for data collection, and all the studied subjects for their consents to join the study. Funding This research received no grant from any funding agency in the public, commercial or not-for-profit sectors.

Disclosures The authors declare that there is no conflict of interest.