Relationship between changes in heart rate recovery after cardiac rehabilitation on cardiovascular mortality in patients with myocardial infarction

A comparison of low and high dose of moderate intensity aerobic exercise on heart rate recovery of the sedentary adults: a pragmatic randomized controlled trial

BACKGROUND

Heart rate recovery (HRR) has been used as a prognostication marker of health. A slower drop in HRR is linked to a higher risk of cardiovascular diseases and all-cause mortality. Since aerobic exercise has been shown to have favorable effects on HRR, we aimed to compare the effects of two different aerobic exercise doses on HRR among a sedentary adult population.

METHODS

A pragmatic randomised controlled trial was conducted on 29 healthy sedentary adults (seven males and 22 females) in a 12-week exercise program. They were randomly assigned to group A (75 min/week, N.=15) or group B (150 min/week, N.=14) of moderate intensity aerobic exercise groups. HRR at 1-minute (HRR1), HRR at 2-minute (HRR2), and peak oxygen uptake (VO<inf>2peak</inf>) were measured pre- and post-intervention.

RESULTS

The improvements of HRR1 and HRR2 were seen in both groups but was only significant (P<0.05) for group A with HRR1, -4.07 bpm (post 24.47±6.42 - pre 20.40±5.51, P=0.018) and HHR2, -3.93 bpm (post 43.40±13.61 - pre 39.47±10.68, P=0.046). Group B showed increment of HRR1, -1.14 bpm (post 21.14±5.35 - pre 20.00±6.30, P=0.286) and HRR2, -2.5 bpm, (post 39.36±8.01 - pre 36.86±9.57, P=0.221). Improvement of the VO<inf>2peak</inf> was only significant in group B with an increment of 1.52±2.61 (P=0.049).

CONCLUSIONS

In conclusion, our study suggests that improvements in heart rate recovery (HRR1 and HRR2) among sedentary healthy adults can be achieved by engaging in moderate intensity exercise at a dose lower than the current recommended guidelines. The lower dose seems to be more attainable and may encourage exercise compliance. Future studies should further explore the effects of different exercise volumes on HRR in a larger sample size and also by controlling for BMI or gender.

Influence of Risk Factors on Exercise Tolerance in Patients after Myocardial Infarction—Early Cardiac Rehabilitation in Poland

(1) Background: Prognosis in patients with cardiovascular diseases is significantly influenced by lifestyle and the control of risk factors. Patients after myocardial infarction require special care and promptly introduced cardiac rehabilitation. The primary aim of this study was to identify risk factors and their influence on exercise tolerance before and after cardiac rehabilitation (CR) provided under the Coordinated Specialist Care Programme—Infarct (CSC-Infarct). (2) Methods: The study was carried out at the Cardiac Rehabilitation Centre of Slupsk Specialist Hospital on a group of 112 patients aged 35–87 (62.78 ± 10.09 years) after myocardial infarction (MI), participating in CSC-Infarct. An exercise test (treadmill ECG test), the 6 min walk test (6MWT), echocardiography, blood test (total cholesterol, HDL, LDL, TG), measurement of diastolic pressure ratio (DPr), waist-to-hip ratio (WHR), and BMI were performed in participants on the first and last day of CR. Rating of perceived exertion was assessed with Borg’s scale. (3) Results: The overweight variable had the strongest effect on the increased value of initial: HR rest, HR max, and HR 1 min after exercise compared to subjects with normal BMI. DPr values before and after CR were also higher in overweight patients. Scores of 6MWT were higher in smokers compared to non-smokers. The final MET value was significantly higher in non-diabetic subjects. Hyperlipidaemia was associated with a higher initial HR max and initial HR 1 min after exercise. DPr before CR was also higher. The initial and final MET values were lower in hypertensive patients. Borg’s rating of perceived exertion measured after the final exercise test was also higher in hypertensive patients. Hypertension influenced the initial and final 6MWT scores, which were significantly higher in normotensive patients. (4) Conclusions: CR within CSC-infarction in patients after myocardial infarction improves exercise tolerance. Exercise tolerance in post-MI patients with concomitant risk factors is lower compared to post-MI patients without risk factors.

Cardiorespiratory fitness measured with cardiopulmonary exercise testing and mortality in patients with cardiovascular disease: A systematic review and meta-analysis

BACKGROUND

Cardiorespiratory fitness (CRF) is inversely associated with mortality in apparently healthy subjects and in some clinical populations, but evidence for the association between CRF and all-cause and/or cardiovascular disease (CVD) mortality in patients with established CVD is lacking. This study aimed to quantify this association.

METHODS

We searched for prospective cohort studies that measured CRF with cardiopulmonary exercise testing in patients with CVD and that examined all-cause and CVD mortality with at least 6 months of follow-up. Pooled hazard ratios (HRs) were calculated using random-effect inverse-variance analyses.

RESULTS

Data were obtained from 21 studies and included 159,352 patients diagnosed with CVD (38.1% female). Pooled HRs for all-cause and CVD mortality comparing the highest vs. lowest category of CRF were 0.42 (95% confidence interval (95%CI): 0.28-0.61) and 0.27 (95%CI: 0.16-0.48), respectively. Pooled HRs per 1 metabolic equivalent (1-MET) increment were significant for all-cause mortality (HR = 0.81; 95%CI: 0.74-0.88) but not for CVD mortality (HR = 0.75; 95%CI: 0.48-1.18). Coronary artery disease patients with high CRF had a lower risk of all-cause mortality (HR = 0.32; 95%CI: 0.26-0.41) than did their unfit counterparts. Each 1-MET increase was associated with lower all-cause mortality risk among coronary artery disease patients (HR = 0.83; 95%CI: 0.76-0.91) but not lower among those with heart failure (HR = 0.69; 95%CI: 0.36-1.32).

CONCLUSION

A better CRF was associated with lower risk of all-cause mortality and CVD. This study supports the use of CRF as a powerful predictor of mortality in this population.

Exercise-Based Interventions in Middle-Aged and Older Adults after Myocardial Infarction: A Systematic Review

This study summarized the relevant literature and aimed to determine the effect of exercise-based interventions after myocardial infarction in middle-aged and older adults. Studies were identified and analyzed according to the PRISMA guidelines. The following electronic databases were used: Google Scholar, PubMed, Mendeley, Science Direct, and Scopus. The identified studies had to be longitudinal, be published in English, have taken place between 2010 and 2020, involve participants who had suffered myocardial infarction, and address different types of exercise-based interventions to be included. Of the 592 relevant studies identified, 20 were included in the qualitative analysis. After analyzing the results obtained, it could be concluded that different types of exercise-based interventions or their combination have a positive effect after myocardial infarction in middle-aged and elderly adults. It can also be suggested that the combination of a cycle ergometer and a treadmill may be the most effective exercise-based intervention. An adequate choice of intensity and volume is crucial, with the optimal duration of the experimental program and the type(s) of exercises adapted to participants after myocardial infarction.

Exercise Enhances the Effect of Bariatric Surgery in Markers of Cardiac Autonomic Function

BACKGROUND

Bariatric surgery improves cardiovascular health, which might be partly ascribed to beneficial alterations in the autonomic nervous system. However, it is currently unknown whether benefits from surgery on cardiac autonomic regulation in post-bariatric patients can be further improved by adjuvant therapies, namely exercise. We investigated the effects of a 6-month exercise training program on cardiac autonomic responses in women undergoing bariatric surgery.

METHODS

Sixty-two women eligible for bariatric surgery were randomly allocated to either standard of care (control) or an exercise training intervention. At baseline (PRE) and 3 (POST3) and 9 (POST9) months after surgery, we assessed chronotropic response to exercise (CR%; i.e., percentage change in heart rate from rest to peak exercise) and heart rate recovery (HRR30s, HRR60s, and HRR120s; i.e., decay of heart rate at 30, 60, and 120 s post exercise) after a maximal exercise test.

RESULTS

Between-group absolute changes revealed higher CR% (Δ = 8.56%, CI95% 0.22-19.90, P = 0.04), HRR30s (Δ = 12.98 beat/min, CI95% 4.29-21.67, P = 0.01), HRR60s (Δ = 22.95 beat/min, CI95% 11.72-34.18, P = 0.01), and HRR120s (Δ = 34.54 beat/min, CI95% 19.91-49.17, P < 0.01) in the exercised vs. non-exercised group.

CONCLUSIONS

Our findings demonstrate that exercise training enhanced the benefits of bariatric surgery on cardiac autonomic regulation. These results highlight the relevance of exercise training as a treatment for post-bariatric patients, ensuring optimal cardiovascular outcomes.

Estimation of Heart Rate Recovery after StairClimbing Using aWrist-Worn Device

Heart rate recovery (HRR) after physical exercise is a convenient method to assess cardiovascular autonomic function. Since stair climbing is a common daily activity, usually followed by a slow walking or rest, this type of activity can be considered as an alternative HRR test. The present study explores the feasibility to estimate HRR parameters after stair climbing using a wrist-worn device with embedded photoplethysmography and barometric pressure sensors. A custom-made wrist-worn device, capable of acquiring heart rate and altitude, was used to estimate the time-constant of exponential decay τ, the short-term time constant S, and the decay of heart rate in 1 min D. Fifty-four healthy volunteers were instructed to climb the stairs at three different climbing rates. When compared to the reference electrocardiogram, the absolute and percentage errors were found to be ≤ 21.0 s (≤ 52.7%) for τ, ≤ 0.14 (≤ 19.2%) for S, and ≤ 7.16 bpm (≤ 20.7%) for D in 75% of recovery phases available for analysis. The proposed approach to monitoring HRR parameters in an unobtrusive way may complement information provided by personal health monitoring devices (e.g., weight loss, physical activity), as well as have clinical relevance when evaluating the efficiency of cardiac rehabilitation program outside the clinical setting.

Effect of exercise training on heart rate recovery in patients post anterior myocardial infarction

Background

Regular exercise training has been shown to reduce mortality, improve functional capacity; and control the risk factors in myocardial infarction (MI) patients. Heart rate recovery (HRR) is a strong independent mortality predictor in patients with previous MI.

Aim

The main objective of this study was to investigate the impact of exercise training on heart rate recovery in patients post anterior myocardial infarction.

Methods

We recruited patients one month after having anterior MI who were referred to cardiac rehabilitation (CR) clinic in Ain Shams University hospital between October 2016 and July 2017. All the patients participated in exercise training sessions 3 times a week for 12 weeks. Symptom limited treadmill exercise test was done before and after exercise training program to calculate heart rate recovery in 1st minute (HRR1) and 2nd minute (HRR2).

Results

A total of 50 patients, including 44 (88%) males, completed the exercise training program. The mean age was 51 years. Statistically significant improvement in HRR1 and HRR2 was observed (p value <0.001) after completion of exercise based cardiac rehabilitation program. Significant improvement in resting heart rate was also observed (p value <0.001). Moreover, metabolic equivalent (METs) and HR reserve were improved significantly (p value <0.001). No statistically significant changes were observed in resting systolic and diastolic blood pressures and maximum HR (p value = 0.95, 0.76 and 0.31 respectively).

Conclusion

Exercise training improves HRR, resting HR, METs and HR reserve in post anterior MI patients.

The prognostic value of heart rate recovery in patients with coronary artery disease: A systematic review and meta-analysis

BACKGROUND

Routine outpatient care of patients with coronary artery disease (CAD) lacks a simple measure of physical fitness and risk of mortality. Heart rate recovery (HRR) is noninvasive and easily obtainable in outpatient settings. Prior studies have suggested that delayed postexercise HRR in the first minutes is associated with mortality in several types of populations. However, a comprehensive overview of the prognostic value of delayed HRR for time to mortality specifically in CAD patients is not available. The purpose of the current meta-analysis is to evaluate the prognostic value of delayed HRR in CAD patients.

METHODS

We conducted a systematic search in OVID MEDLINE and OVID EMBASE to identify studies reporting on HRR and risk of incident cardiovascular events or mortality in CAD patients. Hazard ratios for delayed versus nondelayed HRR were pooled using random-effects meta-analysis.

RESULTS

Four studies were included, comprising 2,428 CAD patients. The study quality of the included studies was rated moderate (n = 2) to high (n = 2). Delayed HRR was defined by ≤12 to ≤21 beat/min in the recovery period. During follow-up (range 2.0-9.8 years), 151 patients died (6.2% [range 2.5%-19.5%]). Only data on mortality could be pooled. Heterogeneity was limited (I² = 32%; P = .23); pooled unadjusted hazard ratio for mortality, based on 3 studies, was 5.8 (95% CI 3.2-10.4).

CONCLUSIONS

In CAD patients, delayed HRR is significantly associated with all-cause mortality. As exercise testing is performed routinely in CAD patients, HRR can be considered in monitoring exercise; still, further research must investigate the addition of HRR in current risk scores.

THE RATE OF CARDIAC RHYTHM RECOVERY POST EXERTION IN PHYSICAL REHABILITATION OF CARDIOLOGICAL PATIENTS

Taken the rising mortality and morbidity of the population due to cardiovascular diseases (CVD), rehabilitation of cardiovascular patients remains actual. Regular exercises are the leading components of cardiorehabilitation, that is evidently beneficial. Taken this, the question raises on the adequacy and efficacy of training regimens. Utilization of the parameter representing the velocity of heart rate decline by every minute of recovery phase after the exertion, is quite informative. The borderline set for heart rate, with increasing cardiovascular risk if below. Dynamics of such parameter during the programs of physical rehabilitation might be a marker of the events efficacy. Recently, there is a deficiency of information on the normal parameters of heart rate recovery rate in CVD patients. Hence a question raises, on the unification of approaches in evaluation of recovery period and data collection on the influence of long term exercises on CVD prognosis.

Long-term intra-individual reproducibility of heart rate dynamics during exercise and recovery in the UK Biobank cohort

Background

The heart rate (HR) response to exercise provides useful information about the autonomic function and has prognostic value, but its reproducibility over a long period of time, a critical requirement for using it as a clinical biomarker, is undetermined.

Aim

To determine the intra-individual reproducibility of HR dynamics during sub-maximum exercise and one minute recovery.

Methods

1187 individuals from the Cardio physical fitness assessment test of the UK Biobank repeated a standard exercise stress test twice (recall time 34.2 ± 2.8 months) and were prospectively studied.

Results

821 individuals complied with inclusion criteria for reproducibility analysis, including peak workload differences between assessments ≤10 W. Intra-individual correlation between HR profile during the first and the second assessment was very high and higher than inter-individual correlation (0.92±0.08 vs 0.87±0.11, p<0.01). Intra-individual correlation of indices describing HR dynamics was: ρ = 0.81 for maximum HR during exercise; ρ = 0.71 for minimum HR during recovery; ρ = 0.70 for HR changes during both exercise and recovery; Intra-individual correlation was higher for these indices of HR dynamics than for resting HR (ρ = 0.64). Bland-Altman plots demonstrated good agreement between HR indices estimated during the first and second assessment. A small but consistent bias was registered for all repeated measurements. The intra-individual consistency of abnormal values was about 60–70%.

Conclusions

The HR dynamics during exercise and recovery are reproducible over a period of 3 years, with moderate to strong intra-individual reproducibility of abnormal values.

Heart Rate Recovery as a Novel Test for Predicting Cardiac Involvement in Beta-Thalassemia Major

BACKGROUND

Abnormal heart rate recovery (HRR) is predictive of cardiac mortality. Autonomic abnormalities in beta-thalassemia major (TM) patients have been reported in previous studies. However, the importance of low HRR in exercise stress test in TM patients has not yet been ascertained. Therefore, this study will be the first of its kind in the literature.

METHODS

Exercise stress test was performed on 56 TM patients who were being treated at the Thalassemia Center of our hospital, along with 46 non-TM iron deficiency anemia (IDA) patients as a control group. Values for HHR were recorded at 1, 2, 3, 4 and 5 min, and HRR was calculated by the difference of heart rate at peak exercise and at a specific time interval following the onset of recovery.

RESULTS

All HRR values were found to be lower in TM patients compared to those in the IDA group. Exercise capacity [metabolic equivalents (METs)] was also found to be low in these patients (p < 0.001) as well. Total exercise time was significantly lower in the TM group compared to the IDA group (8.40 ± 1.7 min vs. 11.17 ± 1.51 min, p < 0.001). Exercise capacity (METs) was also lower in the TM group compared to the IDA group. Mean T2* value was 28.3 ± 13.7 ms in TM patients on magnetic resonance imaging (MRI). In addition, there are 18 TM patients with T2* value was < 20 ms.

CONCLUSIONS

This study found that TM was independently associated with low HRR. Such a condition is an indicator of autonomic dysfunction in TM patients, since abnormal HRR is related to impaired autonomic response. In addition, impaired HRR may be a marker of early cardiac involvement in patients, whose T2* value is high on MRI. Modifying HRR with a cardiac rehabilitation program in TM patients with impaired HRR is a field open for further investigation.

Effects of high-intensity interval versus continuous exercise training on post-exercise heart rate recovery in coronary heart-disease patients

BACKGROUND

Heart rate recovery (HRR) has been considered a prognostic and mortality indicator in both healthy and coronary patients. Physical exercise prescription has shown improvements in VO₂peak and HRR, but most of the studies have been carried out applying continuous training at a moderate intensity, being very limited the use of protocols of high intensity interval training in coronary patients. We aimed to compare the effects of a moderate continuous training (MCT) versus a high intensity interval training (HIIT) programme on VO₂peak and HRR.

METHODS

Seventy three coronary patients were assigned to either HIIT or MCT groups for 8weeks. Incremental exercise tests in a cycloergometer were performed to obtain VO₂peak data and heart rate was monitored during and after the exercise test to obtain heart rate recovery data.

RESULTS

Both exercise programmes significantly increase VO₂peak with a higher increase in the HIIT group (HIIT: 4.5±4.46ml/kg/min vs MCT: 2.46±3.57ml/kg/min; p=0.039). High intensity interval training resulted in a significantly increase in HRR at the first and second minute of the recovery phase (15,44±7,04 vs 21,22±6,62, p<0,0001 and 23,73±9,64 vs 31,52±8,02, p<0,0001, respectively).

CONCLUSIONS

The results of our research show that the application of HIIT to patients with chronic ischemic heart disease of low risk resulted in an improvement in VO₂peak, and also improvements in post-exercise heart-rate recovery, compared with continuous training.

Insomnia symptoms and heart rate recovery among patients in cardiac rehabilitation

Insomnia symptoms (i.e., difficulty falling asleep, difficulty staying asleep, and early morning awakenings) are common among people with cardiovascular disease, and have been linked to adverse cardiovascular health outcomes. Reduced parasympathetic tone is one pathway through which risk may be conferred. The purpose of this study was to evaluate whether insomnia symptoms are associated with lower parasympathetic tone in cardiac rehabilitation patients with suspected insomnia. Participants (N = 121) completed a self-report measure of insomnia severity. 1-min heart rate recovery (HRR), an index of parasympathetic tone, was obtained during a maximal exercise test. Difficulty falling asleep, but not difficulty staying asleep or early awakenings, was associated with attenuated 1-min HRR. When analyses were restricted to participants with moderate and severe insomnia severity (n = 51), the strength of this association increased. In a sample of cardiac rehabilitation patients with insomnia, only the symptom of difficulty falling asleep was associated with lower parasympathetic tone, suggesting that individual insomnia symptoms may show specificity in their associations with physiological mechanisms.

Improvements in heart rate recovery among women after cardiac rehabilitation completion

BACKGROUND

Heart rate recovery (HRR) after exercise cessation is thought to reflect the rate of reestablishment of parasympathetic tone. Relatively little research has focused on improved HRR in women after completing cardiac rehabilitation (CR) exercise training.

OBJECTIVE

We examined the influence of exercise training on HRR in women completing a traditional CR program and in women completing a CR program tailored for women.

METHODS

A 2-group randomized clinical trial compared HRR between 99 women completing a traditional 12-week CR program and 137 women completing a tailored CR program. Immediately upon completion of a symptom-limited graded exercise test, HRR was measured at 1 through 6 minutes.

RESULTS

Compared with baseline, improvement in 1-minute HRR (HRR1) was similar (P = 0.777) between the tailored (mean [SD], 17.5 [11] to 19.1 [12]) and the traditional CR program (15.7 [9.0] to 16.9 [9.5]). The amount of change in the 2-minute HRR (HRR2) for the tailored (30 [13] to 32.8 [14.6]) and traditional programs (28.3 [12.8] to 31.2 [13.7]) also was not different (P = 0.391). Similar results were observed for HRR at 3 through 6 minutes. Given these comparable improvements of the 2 programs, in the full cohort, the factors independently predictive of post-CR HRR1, in rank order, were baseline HRR1 (part correlation, 0.35; P < 0.001); peak exercise capacity, estimated as metabolic equivalents (METs; 0.24, P < 0.001); anxiety (-0.17, P = 0.001); and age (-0.13, P = 0.016). The factors independently associated with post-CR HRR2 were baseline HRR2 (0.44, P < 0.001), peak METs (0.21, P < 0.001), and insulin use (-0.10, P = 0.041).

CONCLUSIONS

One to 6 minutes after exercise cessation, HRR was significantly improved among the women completing both CR programs. The modifiable factors positively associated with HRR1 included peak METs and lower anxiety, whereas HRR2 was associated with insulin administration and peak METs. Additional research on HRR after exercise training in women is warranted.

Low-volume, high-intensity, aerobic interval exercise for sedentary adults: VO₂max, cardiac mass, and heart rate recovery

PURPOSE

The aim of this study was to compare the effects of low-volume, high-intensity aerobic interval training (HAIT) on maximal oxygen consumption (VO₂max), left ventricular (LV) mass, and heart rate recovery (HRR) with high-volume, moderate-intensity continuous aerobic training (CAT) in sedentary adults.

METHODS

Twenty-four healthy but sedentary male adults (aged 29.2 ± 7.2 years) participated in an 8-week, 3-day a week, supervised exercise intervention. They were randomly assigned to either HAIT (18 min, 180 kcal per exercise session) or CAT (45 min, 360 kcal). VO₂max, LV mass (3T-MRI), and HRR at 1 min (HRR-1) and 2 min (HRR-2) after maximal exercise were measured pre- and post-intervention.

RESULTS

Changes in VO₂max during the 8-week intervention were significant (P < 0.01) in both groups (HAIT, 8.7 ± 3.2 ml kg(-1) min(-1), 22.4 ± 8.9%; CAT, 5.5 ± 2.8 ml kg(-1) min(-1), 14.7 ± 9.5%), while the VO₂max improvement in HAIT was greater (P = 0.02) than in CAT. LV mass in HAIT increased (5.1 ± 8.4 g, 5.7 ± 9.1%, P = 0.05), but not in CAT (0.9 ± 7.8 g, 1.1 ± 8.4%, P = 0.71). While changes in HRR-1 were not significant in either group, change in HRR-2 for HAIT (9.5 ± 6.4 bpm, 19.0 ± 16.0%, P < 0.01) was greater (P = 0.03) than for CAT (1.6 ± 10.9 bpm, 3.9 ± 16.2%, P = 0.42).

CONCLUSIONS

This study suggests that HAIT has potential as a time-efficient training mode to improve cardiorespiratory capacity and autonomic nervous system function in sedentary adults.

Clinical usefulness of response profiles to rapidly incremental cardiopulmonary exercise testing

The advent of microprocessed "metabolic carts" and rapidly incremental protocols greatly expanded the clinical applications of cardiopulmonary exercise testing (CPET). The response normalcy to CPET is more commonly appreciated at discrete time points, for example, at the estimated lactate threshold and at peak exercise. Analysis of the response profiles of cardiopulmonary responses at submaximal exercise and recovery, however, might show abnormal physiologic functioning which would not be otherwise unraveled. Although this approach has long been advocated as a key element of the investigational strategy, it remains largely neglected in practice. The purpose of this paper, therefore, is to highlight the usefulness of selected submaximal metabolic, ventilatory, and cardiovascular variables in different clinical scenarios and patient populations. Special care is taken to physiologically justify their use to answer pertinent clinical questions and to the technical aspects that should be observed to improve responses' reproducibility and reliability. The most recent evidence in favor of (and against) these variables for diagnosis, impairment evaluation, and prognosis in systemic diseases is also critically discussed.

Heart rate recovery and heart rate variability are unchanged in patients with coronary artery disease following 12 weeks of high-intensity interval and moderate-intensity endurance exercise training

Decreased heart rate variability and attenuated heart rate recovery following exercise are associated with an increased risk of mortality in cardiac patients. This study investigated the effects of 12 weeks of moderate-intensity endurance exercise (END) and a novel low-volume high-intensity interval exercise protocol (HIT) on measures of heart rate recovery and heart rate variability in patients with coronary artery disease (CAD). Fourteen males with CAD participated in 12 weeks of END or HIT training, each consisting of 2 supervised exercise sessions per week. END consisted of 30-50 min of continuous cycling at 60% peak power output (PPO). HIT involved ten 1-min intervals at 88% PPO separated by 1-min intervals at 10% PPO. Heart rate recovery at 1 min and 2 min was measured before and after training (pre- and post-training, respectively) using a submaximal exercise bout. Resting time and spectral and nonlinear domain measures of heart rate variability were calculated. Following 12 weeks of END and HIT, there was no change in heart rate recovery at 1 min (END, 40 ± 12 beats·min(-1) vs. 37 ± 19 beats·min(-1); HIT, 31 ± 8 beats·min(-1) vs. 35 ± 8 beats·min(-1); p ≥ 0.05 for pre- vs. post-training) or 2 min (END, 44 ± 18 beats·min(-1) vs. 43 ± 19 beats·min(-1); HIT, 42 ± 10 beats·min(-1) vs. 50 ± 6 beats·min(-1); p ≥ 0.05 for pre- vs. post-training). All heart rate variability indices were unchanged following END and HIT training. In conclusion, neither END nor HIT exercise programs elicited training-induced improvements in cardiac autonomic function in patients with CAD. The absence of improvements with training may be attributed to the optimal medical management and normative pretraining state of our sample.

Heart rate recovery after exercise and long-term prognosis in patients with coronary artery disease

BACKGROUND

The long-term prognostic value of heart rate recovery (HRR) has been incompletely documented in patients with coronary artery disease (CAD). We sought to confirm the prognostic value of HRR in a large cohort with stable CAD.

METHODS

From the Coronary Artery Surgery Study registry, a database of 24,958 patients with CAD who underwent cardiac catheterization between 1974 and 1979, we identified 4097 patients with baseline exercise stress testing data. HRR was measured at 3 minutes post exercise during a passive recovery. Clinical outcomes were evaluated according to HRR in both threshold and continuous models.

RESULTS

Median long-term follow-up was 14.7 years (interquartile range, 9.8-16.2). HRR < 46 beats per minute (Bpm) most appropriately differentiated nonsurvivors from survivors (area under receiver operating characteristic curve = 0.613) and was associated with an increased risk of all-cause death (adjusted hazard ratio = 1.15; P = 0.011). Increasing HRR was associated with a lower risk of all-cause (adjusted hazard ratio = 0.94 per 10 Bpm; 95% confidence interval, 0.91-0.97; P = 0.0005) and cardiovascular (CV) mortality (adjusted hazard ratio = 0.94 per 10 Bpm; 95% confidence interval, 0.90-0.98; P = 0.003).

CONCLUSIONS

HRR at 3 minutes independently predicts long-term all-cause and CV mortality in patients with stable CAD. Measurement of HRR at 3 minutes during passive recovery can be used as a complementary tool to identify patients with a higher total and CV risk.

Impact of exercise on heart rate recovery

BACKGROUND

Abnormal heart rate recovery (HRR) has been shown to predict mortality. Although small studies have found that HRR can be improved with cardiac rehabilitation, it is unknown whether an improvement would affect mortality. The aim of this study was to determine whether HRR could be improved with cardiac rehabilitation and whether it would be predictive of mortality.

METHODS AND RESULTS

We evaluated 1070 consecutive patients who underwent exercise stress testing before and after completion of a phase 2 cardiac rehabilitation program. Heart rate recovery, defined as the difference between heart rate at peak exercise and exactly 1 minute into the recovery period, and mortality were followed up as the primary end points. Of 544 patients with abnormal baseline HRR, 225 (41%) had normal HRR after rehabilitation. Of the entire cohort, 197 patients (18%) died. Among patients with an abnormal HRR at baseline, failure to normalize after rehabilitation predicted a higher mortality (P<0.001). After multivariable adjustment, the presence of an abnormal HRR at exit was predictive of death in all patients (hazard ratio, 2.15; 95% confidence interval 1.43-3.25). Patients with abnormal HRR at baseline who normalized afterward had survival rates similar to those of the group with normal HRR at baseline and after cardiac rehabilitation (P=0.143).

CONCLUSIONS

Heart rate recovery improved after phase 2 cardiac rehabilitation in the overall cohort. There was a strong association of abnormal HRR at exit with all-cause mortality. Patients with abnormal HRR at baseline who normalized HRR with exercise had a mortality similar to that of individuals with baseline normal HRR.