Cardiopulmonary fitness and heart rate recovery as predictors of mortality in a referral population

Independent prognostic value of high-risk ventricular premature complexes during exercise or recovery in asymptomatic patients: A meta-analysis of observational studies

INTRODUCTION

Ventricular premature contractions (VPCs) are a common finding during cardiac stress tests. The independent prognostic value of these findings in patients in asymptomatic patients is unclear.

METHODS

We conducted a systematic review and meta-analysis of observational studies exploring the independent prognostic value of VPCs to predict all-cause mortality. The secondary outcome was cardiovascular (CV) mortality. We excluded studies that did not report outcomes after adjusting for ≥1 confounder. Random effect meta-analyses were used to predict cumulative hazard ratios. We stratified results based on VPC during exercise or recovery.

RESULTS

We found 7 studies with 24,518 patients that met our inclusion criteria. Two studies reported all-cause mortality only, 1 study reported CV mortality only, rest 4 reported both. There was significant heterogeneity in the baseline population, definition of high-risk VPCs, and variables used in adjusted models. Using multivariable summary estimates from individual studies, only VPCs during exercise were associated with a higher risk of all-cause mortality (HR 1.27, 95 % CI 1.07, 1.48). Both VPCs during exercise and recovery were associated with a higher risk CV mortality (HR 1.69, 95 % CI 1.19, 2.20, I2 = 17.6 % and 1.62, 95 % CI 1.25, 2.00, p < 0.001 for both).

CONCLUSION

High-risk VPCs during exercise is associated with increased risk of all-cause and CV mortality, while those during recovery are associated with an increased risk of CV mortality only.

Lifestyle Patterns in Patients with Type 2 Diabetes

Modern lifestyles have led to sedentary behavior, lower participation in active movement and physical activities during leisure time, unhealthy diets, and increased exposure to stress. It is important to examine the interaction of several lifestyle risk factors instead of focusing on one alone. The purpose of this study was to identify lifestyle patterns in a group of patients with type 2 diabetes and the associations of its components with certain metabolic parameters. Using principal component analysis, we identified three dietary patterns: the prudent pattern (fat, oil, cereals, potatoes, vegetables, fish, nuts, seeds and fruits), the Western pattern (meat and meat products, eggs and soft drinks) and the traditional pattern (milk and its derivatives, soups and sauces, with a low intake of sugar/snacks). In addition, using the same method of analysis, we identified two lifestyle patterns: the inadequate lifestyle pattern (Western dietary pattern, increased hours of sleep and lower levels of stress) and the traditional lifestyle pattern (traditional dietary pattern, increased physical activity (PA) and non-smoking status). The inadequate lifestyle pattern was associated with younger age, hypertension and diabetic neuropathy. The traditional lifestyle pattern was related to lower postprandial blood glucose levels. Sedentary individuals were more likely to be over 65 years old and to have higher glycated hemoglobin (HbA1c). Smokers were also more likely to have inadequate glycemic and lipid profile control.

Genome-wide association studies: utility and limitations for research in physiology

Physiological systems are subject to interindividual variation encoded by genetics. Genome-wide association studies (GWAS) operate by surveying thousands of genetic variants from a substantial number of individuals and assessing their association to a trait of interest, be it a physiological variable, a molecular phenotype (e.g. gene expression), or even a disease or condition. Through a myriad of methods, GWAS downstream analyses then explore the functional consequences of each variant and attempt to ascertain a causal relationship to the phenotype of interest, as well as to delve into its links to other traits. This type of investigation allows mechanistic insights into physiological functions, pathological disturbances and shared biological processes between traits (i.e. pleiotropy). An exciting example is the discovery of a new thyroid hormone transporter (SLC17A4) and hormone metabolising enzyme (AADAT) from a GWAS on free thyroxine levels. Therefore, GWAS have substantially contributed with insights into physiology and have been shown to be useful in unveiling the genetic control underlying complex traits and pathological conditions; they will continue to do so with global collaborations and advances in genotyping technology. Finally, the increasing number of trans-ancestry GWAS and initiatives to include ancestry diversity in genomics will boost the power for discoveries, making them also applicable to non-European populations.

Nonexercise machine learning models for maximal oxygen uptake prediction in national population surveys

OBJECTIVE

Nonexercise algorithms are cost-effective methods to estimate cardiorespiratory fitness (CRF), but the existing models have limitations in generalizability and predictive power. This study aims to improve the nonexercise algorithms using machine learning (ML) methods and data from US national population surveys.

MATERIALS AND METHODS

We used the 1999-2004 data from the National Health and Nutrition Examination Survey (NHANES). Maximal oxygen uptake (VO2 max), measured through a submaximal exercise test, served as the gold standard measure for CRF in this study. We applied multiple ML algorithms to build 2 models: a parsimonious model using commonly available interview and examination data, and an extended model additionally incorporating variables from Dual-Energy X-ray Absorptiometry (DEXA) and standard laboratory tests in clinical practice. Key predictors were identified using Shapley additive explanation (SHAP).

RESULTS

Among the 5668 NHANES participants in the study population, 49.9% were women and the mean (SD) age was 32.5 years (10.0). The light gradient boosting machine (LightGBM) had the best performance across multiple types of supervised ML algorithms. Compared with the best existing nonexercise algorithms that could be applied to the NHANES, the parsimonious LightGBM model (RMSE: 8.51 ml/kg/min [95% CI: 7.73-9.33]) and the extended LightGBM model (RMSE: 8.26 ml/kg/min [95% CI: 7.44-9.09]) significantly reduced the error by 15% and 12% (P < .001 for both), respectively.

DISCUSSION

The integration of ML and national data source presents a novel approach for estimating cardiovascular fitness. This method provides valuable insights for cardiovascular disease risk classification and clinical decision-making, ultimately leading to improved health outcomes.

CONCLUSION

Our nonexercise models provide improved accuracy in estimating VO2 max within NHANES data as compared to existing nonexercise algorithms.

Prediction of Relevant Training Control Parameters at Individual Anaerobic Threshold without Blood Lactate Measurement

BACKGROUND

Active exercise therapy plays an essential role in tackling the global burden of obesity. Optimizing recommendations in individual training therapy requires that the essential parameters heart rate HR(IAT) and work load (W/kg(IAT) at individual anaerobic threshold (IAT) are known. Performance diagnostics with blood lactate is one of the most established methods for these kinds of diagnostics, yet it is also time consuming and expensive.

METHODS

To establish a regression model which allows HR(IAT) and (W/kg(IAT) to be predicted without measuring blood lactate, a total of 1234 performance protocols with blood lactate in cycle ergometry were analyzed. Multiple linear regression analyses were performed to predict the essential parameters (HR(IAT)) (W/kg(IAT)) by using routine parameters for ergometry without blood lactate.

RESULTS

HR(IAT) can be predicted with an RMSE of 8.77 bpm (p < 0.001), R² = 0.799 (|R| = 0.798) without performing blood lactate diagnostics during cycle ergometry. In addition, it is possible to predict W/kg(IAT) with an RMSE (root mean square error) of 0.241 W/kg (p < 0.001), R² = 0.897 (|R| = 0.897).

CONCLUSIONS

It is possible to predict essential parameters for training management without measuring blood lactate. This model can easily be used in preventive medicine and results in an inexpensive yet better training management of the general population, which is essential for public health.

Heart Rate Recovery (HRR) Is Not a Singular Predictor for Physical Fitness

BACKGROUND

For optimal recommendations in cardiovascular training for the general population, knowing the essential parameters for physical fitness is required. Heart rate recovery (HRR) is an easy-to-measure parameter and is discussed to derive the physical fitness of an individual subject. This study evaluates HRR as a potential physical fitness parameter for public health programs, as it is measured in every ergometry.

METHODS

In this retrospective cross-sectional study, we analyzed HRR regarding physical fitness (W/kg (IAT: individual anaerobic threshold)). In total, we analyzed 1234 performance protocols in cycle ergometry. Significance tests (p < 0.001) and multiple linear regression were performed.

RESULTS

The analysis of HRR and weight-related performance showed a significant correlation with a moderate coefficient of determination (R² = 0.250). The coefficient of determination increases from very weak correlation levels at 1 min post-workout towards weak to moderate levels of correlation at 5 min post-workout.

CONCLUSIONS

In this study HRR and the weight-related performance at the IAT showed a significant correlation with a mean strength. Thus, a prediction or conclusion on physical performance based singularly on HRR decrease is not recommended. However, in preventive medicine, HRR should be measured and observed on a long-term basis, for analysis of vagal activity and to draw to inferences of mortality.

Revisiting exercise-induced premature ventricular complexes as a prognostic factor for mortality in asymptomatic patients: A systematic review and meta-analysis

Background

Recent investigations suggest that premature ventricular complexes (PVCs) during an exercise test are associated with an elevated risk of mortality in asymptomatic individuals. However, given the small number of studies included, the association between these two entities in the asymptomatic population remains obscure. Our aim was to evaluate this matter.

Methods

A comprehensive literature search was conducted utilizing several online databases up to April 2022. The study comprised cohort studies examining the relationship between exercise-induced premature ventricular complexes (EI-PVCs) and all-cause mortality (ACM) as well as cardiovascular mortality (CVM) in asymptomatic populations. To provide diagnostic values across the statistically significant parameters, we additionally calculated sensitivity, specificity, and area under the curve (AUC).

Results

A total of 13 studies consisting of 82,161 patients with a mean age of 49.3 years were included. EI-PVCs were linked to an increased risk of ACM (risk ratio (RR) = 1.30 (95% confidence interval (CI) = 1.18–1.42); p &lt; 0.001; I2 = 59.6%, p-heterogeneity &lt; 0.001) and CVM (RR = 1.67 (95% CI = 1.40–1.99); p &lt; 0.001; I2 = 7.5%, p-heterogeneity = 0.373). Subgroup analysis based on the frequency of PVCs revealed that frequent PVCs were similarly related to a higher risk of ACM and CVM, but not infrequent PVCs. Moreover, diagnostic test accuracy meta-analysis showed that recovery phase EI-PVCs have a higher overall specificity than exercise phase EI-PVCs regarding our outcomes of interest.

Conclusion

EI-PVCs are correlated with a higher risk of ACM and CVM. When compared to the exercise phase, the specificity of PVCs generated during the recovery period in predicting interest outcomes is higher. As a result, we propose that the exercise ECG be utilized on a regular basis in middle-aged asymptomatic individuals to measure the frequency of PVCs and stratify the risk of mortality.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=328852], identifier [CRD42022328852].

A Clinician's Guide to Smartwatch "Interrogation"

Purpose of Review

Wearable technology is rapidly evolving and the data that it can provide regarding an individual’s health is becoming increasingly important for clinicians to consider. The purpose of this review is to help inform health care providers of the benefits of smartwatch interrogation, with a focus on reviewing the various parameters and how to apply the data in a meaningful way.

Recent Findings

This review details interpretation of various parameters found commonly in newer smartwatches such as heart rate, step count, ECG, heart rate recovery (HRR), and heart rate variability (HRV), while also discussing potential pitfalls that a clinician should be aware of.

Summary

Smartwatch interrogation is becoming increasingly relevant as the continuous data it provides helps health care providers make more informed decisions regarding diagnosis and treatment. For this reason, we recommend health care providers familiarize themselves with the technology and integrate it into clinical practice.

Heart Rate Response to Exercise and Recovery: INDEPENDENT PROGNOSTIC MEASURES IN PATIENTS WITHOUT KNOWN MAJOR CARDIOVASCULAR DISEASE

PURPOSE

Heart rate response during exercise testing (ET) provides valuable prognostic information. Limited data are available regarding the prognostic interplay of heart rate (HR) measured at rest, exercise and recovery phases of ET, and its ability to predict risk beyond exercise capacity.

METHODS

Retrospective analysis of treadmill ETs was performed by the Bruce protocol in patients aged 35-75 yr without known cardiovascular disease (CVD; n = 13 887; 47% women). Heart rate recovery at 2 min (HRR2; defined abnormal <42 beats) and chronotropic index (CI; defined abnormal <80%, determined as age-predicted HR reserve) were analyzed in association with the risk of developing myocardial infarction, stroke, or death (major adverse cardiovascular event [MACE]) during median follow-up of 6.5 yr.

RESULTS

The HRR2 <42 beats and CI <80% were each associated with increased risk of MACE: adjusted hazard ratios with 95% confidence interval 1.47: 1.27-1.72 and 1.66: 1.42-1.93, P < .001, respectively, evident also when analyzed as continuous variables. Strength of association of HRR2 and CI with outcome was attenuated but remained significant with further adjustment for exercise duration and metabolic equivalents. Having both HRR2 and CI abnormal compared with only one measure abnormal was associated with hazard ratios with 95% confidence interval of 1.66: 1.38-2.00 and 1.48: 1.22-1.79 for MACE, before and after adjustment for cardiorespiratory fitness (CRF). The degree of CRF (low vs mid/high) did not modify the prognostic effect of HRR2 and CI (P-for-interaction nonsignificant).

CONCLUSIONS

Both HRR2 and CI provide independent prognostic information beyond CRF in patients without CVD referred for ET. The predictive ability is more pronounced when both abnormal HR measures coexist.

High-Intensity Interval Training Improves Cardiac Autonomic Function in Patients with Type 2 Diabetes: A Randomized Controlled Trial

Different exercise models have been used in patients with type 2 diabetes mellitus (T2D), like moderate intensity continuous training (MICT) and high intensity interval training (HIIT); however, their effects on autonomic modulation are unknown. The present study aimed to compare the effects of different exercise modes on autonomic modulation in patients with T2D. In total, 44 adults with >5 years of T2D diagnosis were recruited and stratified into three groups: HIIT-30:30 (n = 15, age 59.13 ± 5.57 years) that performed 20 repetitions of 30 s at 100% of VO2peak with passive recovery, HIIT-2:2 (n = 14, age 61.20 ± 2.88) that performed 5 repetitions of 2 min at 100% of VO2peak with passive recovery, and MICT (n = 15, age 58.50 ± 5.26) that performed 14 min of continuous exercise at 70% of VO2peak. All participants underwent anamnesis and evaluation of cardiorespiratory fitness and cardiac autonomic modulation. All protocols were equated by total distance and were performed two times per week for 8 weeks. Group × time interactions were observed for resting heart rate (HRrest) [F(2.82) = 3.641; p = 0.031] and SDNN [F(2.82) = 3.462; p = 0.036]. Only the HIIT-30:30 group significantly reduced SDNN (p = 0.002 and 0.025, respectively). HRrest reduced more in the HIIT-30:30 group compared with the MICT group (p = 0.038). Group × time interactions were also observed for offTAU [F(2.82) = 3.146; p = 0.048] and offTMR [F(2.82) = 4.424; p = 0.015]. The MICT group presented increased values of offTAU compared with the HIIT-30:30 and HIIT-2:2 groups (p = 0.001 and 0.013, respectively), representing a slower HR response after eight weeks of intervention. HIIT, specially HIIT-30:30, represents a promising measure for improving autonomic modulation in patients with T2D.

Cardiovascular Disease and All-Cause Mortality in Male Twins With Discordant Cardiorespiratory Fitness: A Nationwide Cohort Study

Whether genetic and familial factors influence the association between cardiorespiratory fitness (CRF) and cardiovascular disease (CVD) is unknown. Two cohorts were formed based on data from 1,212,295 men aged 18 years who were conscripted for military service in Sweden during 1972-1996. The first comprised 4,260 twin pairs in which the twins in each pair had different CRF (≥1 watt). The second comprised 90,331 nonsibling pairs with different CRF and matched on birth year and year of conscription. Incident CVD and all-cause mortality were identified using national registers. During follow-up (median 32 years), there was no difference in CVD and mortality between fitter twins and less fit twins (246 vs. 251 events; hazard ratio (HR) = 1.00, 95% confidence interval (CI): 0.83, 1.20). The risks were similar in twin pairs with ≥60-watt difference in CRF (HR = 0.96, 95% CI: 0.57, 1.64). In contrast, in the nonsibling cohort, fitter men had a lower risk of the outcomes than less fit men (4,444 vs. 5,298 events; HR = 0.83, 95% CI: 0.79, 0.86). The association was stronger in pairs with ≥60-watt difference in CRF (HR = 0.65, 95% CI: 0.59, 0.71). These findings indicate that genetic and familial factors influence the association of CRF with CVD and mortality.

Impact of unhealthy lifestyle on cardiorespiratory fitness and heart rate recovery of medical science students

Background

Medical science students represent valuable labour resources for better future medicine and medical technology. However, little attention was given to the health and well-being of these early career medical science professionals. The aim of this study is to investigate the impact of lifestyle components on cardiorespiratory fitness and heart rate recovery measured after moderate exercise in this population.

Methods

Volunteers without documented medical condition were recruited randomly and continuously from the first-year medical science students during 2011–2014 at the University of Surrey, UK. Demographics and lifestyle components (the levels of smoking, alcohol intake, exercise, weekend outdoor activity and screen-time, daily sleep period, and self-assessment of fitness) were gathered through pre-exercise questionnaire. Cardiorespiratory fitness (VO₂max) and heart rate recovery were determined using Åstrand–Rhyming submaximal cycle ergometry test. Data were analysed using SPSS version 25.

Results

Among 614 volunteers, 124 had completed both lifestyle questionnaire and the fitness test and were included for this study. Within 124 participants (20.6 ± 4 years), 46.8% were male and 53.2% were female, 11.3% were overweight and 8.9% were underweight, 8.9% were current smokers and 33.1% consumed alcohol beyond the UK recommendation. There were 34.7% of participants admitted to have < 3 h/week of moderate physical activity assessed according to UK Government National Physical Activity Guidelines and physically not fit (feeling tiredness). Fitness test showed that VO₂max distribution was inversely associated with heart rate recovery at 3 min and both values were significantly correlated with the levels of exercise, self-assessed fitness and BMI. Participants who had < 3 h/week exercise, or felt not fit or were overweight had significantly lower VO₂max and heart rate recovery than their peers.

Conclusion

One in three new medical science students were physically inactive along with compromised cardiorespiratory fitness and heart rate recovery, which put them at risk of cardiometabolic diseases. Promoting healthy lifestyle at the beginning of career is crucial in keeping medical science professionals healthy.

Effect of short moderate intensity exercise bouts on cardiovascular function and maximal oxygen consumption in sedentary older adults

AIM

To investigate effect of <10 min moderate intensity exercise on cardiovascular function and maximal oxygen consumption (V ˙ O2max) among sedentary adults.

METHODS

We studied 53 sedentary urbanites aged ≥50 years, randomised into: (1) male (MS) and (2) female (FS) undertaking three short-duration exercise (5-10 min) daily, and (3) male (ML) and (4) female (FL) exercising 30-60 min 3-5 days weekly. Resting systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate andV ˙ O2max were measured at baseline and 8 weekly for 24 weeks.

RESULTS

At baseline, 50% MS, 61.5% ML, 53.8% FS and 53.8% FL had SBP ≥120 mm Hg, and 14.3% MS, 53.8% ML, 23.1% FS and 38.5% FL had DBP ≥80 mm Hg. At 24 weeks, where SBP remained ≥120 mm Hg, values decreased from 147±19.2 to 132.3±9.6 mm Hg (50% of MS), from 144±12.3 to 128±7.0 mm Hg (23.1% of ML), from 143.1±9.6 to 128.0±7.0 mm Hg (53.8% of FS) and from 152.3±23.7 to 129±3.7 mm Hg (30.8% of FL). For DBP ≥80 mm Hg, MS and FS percentages maintained, but values decreased from 101±15.6 to 84.5±0.7 mm Hg (MS) and 99.0±3.6 to 87.7±4.9 mm Hg (FS). In ML and FL, percentage with DBP ≥80 mm Hg dropped to 15.4% (86.1±6.5 to 82.5±3.5 mm Hg) and (91.4±5.3 to 83.5±0.71 mm Hg).V ˙ O2max increased from 26.1±4.4 to 32.0±6.2 for MS, from 25.8±5.1 to 28.8±5.4 for ML (group differences p=0.02), from 20.2±1.8 to 22.7±2.0 for FS and from 21.2±1.9 to 24.2±2.7 for FL (groups differences p=0.38).

CONCLUSION

Accumulated moderate intensity exercise bouts of <10 min confer similar-to-better cardiovascular andV ˙ O2max improvements compared with current recommendations among sedentary adults.

Combination of low blood pressure response, low exercise capacity and slow heart rate recovery during an exercise test significantly increases mortality risk

Aims: We investigated the combination of low systolic blood pressure (SBP) response, low exercise capacity (EC) and slow heart rate recovery (HRR) during an exercise test in mortality prediction.Patients and methods: Our population consisted of 3456 patients from the Finnish Cardiovascular Study. A failure of SBP to increase >42 mmHg was defined as a low response. Low EC was defined as  < 8 metabolic equivalents. 1-minute HRR ≤18 bpm from maximum was defined as slow HRR.Results: During a median follow up of 10.0 years, 537 participants died. Reduced SBP response, low EC and slow HRR were independent predictors of all-cause and CV mortality (p < .001 for all). Patients with reduced SBP response, low EC and slow HRR had a very high mortality rate of 42.1% during follow up compared to only 4.5% of the patients without any of these risk factors. The hazard ratios for all-cause mortality in patients with one, two or three of the studied risk factors were 3.2, 6.0, and 10.6, respectively (p < .001 for all).Conclusion: The combination of reduced SBP response, low exercise capacity, and reduced HRR in an exercise test is associated with very high mortality and can be used in risk stratification.Key messagesThe combination of low blood pressure response, low exercise capacity and slow heart rate recovery in an exercise test is able to identify a group of patients in a very high mortality risk.These parameters are easily derived from an exercise test.All parameters are commonly available in clinical practice.

Quantitative Assessment of Autonomic Regulation of the Cardiac System

Autonomic neural system (ANS) regulates the circulation to provide optimal perfusion of every organ in accordance with its metabolic needs, and the quantitative assessment of autonomic regulation is crucial for personalized medicine in cardiovascular diseases. In this paper, we propose the Dystatis to quantitatively evaluate autonomic regulation of the human cardiac system, based on homeostatis and probabilistic graphic model, where homeostatis explains ANS regulation while the probability graphic model systematically defines the regulation process for quantitative assessment. The indices and measurement methods for three well-designed scenarios are also illustrated to evaluate the proposed Dystatis: (1) heart rate variability (HRV), blood pressure variability (BPV), and respiration synchronization (Synch) in resting situation; (2) chronotropic competence indices (CCI) in graded exercise testing; and (3) baroreflex sensitivity (BRS), sympathetic nerve activity (SNA), and parasympathetic nerve activity (PNA) in orthostatic testing. The previous clinical results have shown that the proposed method and indices for autonomic cardiac system regulation have great potential in prediction, diagnosis, and rehabilitation of cardiovascular diseases, hypertension, and diabetes.

Predictive maximal heart rate equations in child and adolescent athletes: a systematic review

Abstract Introduction: The maximal heart rate (HRmax) is considered the highest value of HR achieved during a physical effort close to exhaustion. Objective: To evaluate the applicability of the predictive HRmax equations during exercise tests in child and adolescent athletes through a systematic review. Methods: It is a systematic review, through Scopus, Pubmed, Lilacs, Scielo and PEDro. The included studies compared the measured and estimated HRmax predictive equations during exercise tests in child and adolescent athletes. The following search strategy was used: “Exercise test OR Exercise testing OR Cardiopulmonary exercise test OR Cardiopulmonary exercise testing OR Peak oxygen uptake OR Maximal oxygen consumption OR Exercise capacity OR Heart rate OR Heart rate OR Pulse rate OR Pulse rates OR Heart rate control OR Cardiac chronotropic OR Predictive value test AND Predictive equations”. Results: From a total of 1,664 articles, only 4 were included. All compared the measured HRmax values with those estimated by the “220 - age” equation; 3 used the formula “208 - (0.7 x age)”, and only 1 used the “223 - (1.44 x age)” equation. Although all of them stated that the “220 - age” equation overestimates HRmax, the formula “208 - (0.7 x age”) underestimated (2 articles) and overestimated (1 study) the measured results, while the equation “213 - (1.44 x age) was also not adequate. Conclusion: The use of predictive HRmax equations for child and adolescent athletes does not seem to be recommended. The use of cohort points for these estimates is carefully recommended.

Significance of an Increase in Diastolic Blood Pressure During a Stress Test in Terms of Comorbidities and Long-Term Total and CV Mortality

BACKGROUND

A decrease in diastolic blood pressure (DBP) with exercise is considered normal, but the significance of an increase in DBP has not been validated. Our aim was to determine the relationship of DBP increasing on a stress test regarding comorbidities and mortality.

METHODS

Our database was reviewed from 1993 to 2010 using the first stress test of a patient. Non-Minnesota residence, baseline cardiovascular (CV) disease, rest DBP <60 or >100 mm Hg, and age <30 or ≥80 were exclusion criteria. DBP response was classified: normal if peak DBP-rest DBP < 0, borderline 0-9, and abnormal ≥10 mm Hg. Mortality was determined from Mayo Clinic records and Minnesota Death Index. Logistic regression was used to determine the relationship of DBP response to the presence of comorbidities. Cox regression was used to determine total and CV mortality risk by DBP response. All analyses were adjusted for age, sex, and resting DBP.

RESULTS

Twenty thousand seven hundred sixty patients were included (51 ± 11 years, female n = 7,314). Rest/peak averaged DBP 82 ± 8/69 ± 15 mm Hg in normal vs. 79 ± 9/82 ± 9 mm Hg in borderline vs. 76 ± 9/92 ± 11 mm Hg in abnormal DBP response. There were 1,582 deaths (8%) with 557 (3%) CV deaths over 12 ± 5 years of follow-up. In patients with borderline and abnormal DBP response, odds ratios for obesity, hypertension, diabetes, and current smoking were significant, while hazard ratios for total and CV death were not significant compared with patients with normal DBP response.

CONCLUSIONS

DBP response to exercise is significantly associated with important comorbidities at the time of the stress test but does not add to the prognostic yield of stress test.

Prognostic Performance of Heart Rate Recovery on an Exercise Test in a Primary Prevention Population

BACKGROUND

Heart rate (HR) recovery has been investigated in specific patient cohorts, but there is less information about the role of HR recovery in general populations. We investigated whether HR recovery has long-term prognostic significance in primary prevention.

METHODS AND RESULTS

Exercise tests performed between 1993 and 2010 on patients aged 30 to 79 years without cardiovascular disease were included. Mortality was determined from Mayo Clinic records and Minnesota Death Index. Total, cardiovascular, and non-cardiovascular mortality was reported according to HR recovery <13 bpm using Cox regression. 19 551 patients were included, 6756 women (35%), age 51±10 years. There were 1271 deaths over follow-up of 12±5 years. HR recovery declined after age 60, and was also lower according to diabetes mellitus, hypertension, obesity, current smoking, and poor cardiorespiratory fitness but not sex or β-blockers. Adjusting for these factors, abnormal HR recovery was a significant predictor of total (hazard ratio [95% confidence interval]=1.56 [1.384-1.77]), cardiovascular (1.95 [1.57-2.42]), and non-cardiovascular death (1.41 [1.22-1.64]). Hazard ratios for cardiovascular death according to abnormal HR recovery were significant in all age groups (30-59, 60-69, 70-79), in both sexes, in patients with and without hypertension, obesity, and diabetes mellitus, but not in patients taking β-blockers, current smokers, and patients with normal cardiorespiratory fitness.

CONCLUSIONS

HR recovery is a powerful prognostic factor predicting total, cardiovascular, and non-cardiovascular death in a primary prevention cohort. It performs consistently well according to sex, age, obesity, hypertension, and diabetes mellitus but shows diminished utility in patients taking β-blockers, current smokers, and patients with normal cardiorespiratory fitness.

Impact of Cardiorespiratory Fitness on Frequency of Atrial Fibrillation, Stroke, and All-Cause Mortality

Benefits of cardiorespiratory fitness on cardiovascular health are well recognized, but the impact on incidence of atrial fibrillation (AF) and stroke, and, particularly, risk of stroke and mortality in patients with AF is less clear. From 1993 to 2010, patients referred for a treadmill exercise test (TMET) at the Mayo Clinic Rochester, MN, were retrospectively identified (N = 76,857). From this, 14,094 local residents were selected. Exclusions were age <18 years; history of heart failure, structural or valvular heart disease, AF or flutter, or stroke. Subjects were divided into 4 groups at baseline based on quartiles of functional aerobic capacity (FAC) and followed through January 2016. The final study cohort included 12,043 patients. During median follow-up of 14 (9 to 17) years, 1,222 patients developed incident AF, 1,128 developed stroke, and 1,590 patients died. Each 10% increase in FAC was associated with decreased risk of incident AF, stroke, and mortality by 7% (0.93 [0.91 to 0.96, p < 0.001]), 8% (0.92 [0.89 to 0.94, p < 0.001]), and 16% (0.84 [0.82 to 0.86, p < 0.001]), respectively. In patients who developed incident AF with baseline FAC <75% versus ≥105%, risks of both stroke (1.40 [1.04 to 1.90, p = 0.01]) and mortality (3.20 [2.11 to 4.58, p < 0.001]) were significantly higher. In conclusion, better cardiorespiratory fitness is associated with lower risk of incident AF, stroke, and mortality. Similarly, risk of stroke and mortality in patients with AF is also inversely associated with cardiorespiratory fitness.

Heart Rate Recovery and Cancer Risk: Prospective Cohort Study

This study aims to determine the association between 2-minute heart rate recovery (HRR) and cancer risk. Each participant (5379 women; 8485 men) provided HRR obtained from treadmill tests. The outcome was site-specific cancer. Over 9 years of follow-up, 630 cancer events (258 women) were accrued. Slower HRR was associated with increased thyroid cancer risk in women ( P for trend = .0121) and colorectal cancer risk in men ( P for trend = .0034). The lowest HRR (<13 bpm) had higher hazards of thyroid cancer (hazard ratio [HR] = 2.20; 95% CI = 1.28-3.77) in women and colorectal cancer (HR = 3.08; 95% CI = 1.32-7.15) in men. In women, slower HRR and lower proportions of heart rate recovery (PHRR) were associated with higher hazards of thyroid cancer in women and metabolically related cancers (liver and colorectal) in men. Slower HRR and lower PHRR were independent risk factors for thyroid cancer in women and metabolically related cancers in men.

Chronotropic Competence Indices Extracted from Wearable Sensors for Cardiovascular Diseases Management

Chronotropic incompetence (CI) has been proven to be an important factor in the diagnosis and management of cardiovascular diseases. In this paper, we extend the existing CI parameters and propose chronotropic competence indices (CCI) to describe the exercise response of the cardiopulmonary system. A cardiac chronotropic competence Test (3CT), dedicated to CCI measurement using a wearable device, is also presented. Preliminary clinical trials are presented for the validation of 3CT measurement accuracy, and to show the potential of CCI in the prevention and rehabilitation of cardiovascular diseases.

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.

Objectively-Measured Free-Living Physical Activity and Heart Rate Recovery

The purpose of this study was to examine the association of free-living, objectively-measured physical activity on treadmill-based heart rate recovery (HRR), a parameter known to associate with morbidity and mortality. Data was used from 2003 to 2004 NHANES. Physical activity was assessed via accelerometry, with HRR recovery assessed from a treadmill-based test. Heart rate recovery minute 1 (HRR₁) and minute 2 (HRR₂) were calculated. After adjustment, light and vigorous-intensity free-living physical activity, respectively, were associated with HRR₁ (β_adjusted = 0.69, 95% CI 0.22-1.14; β_adjusted 1.94, 95% CI 0.01-3.9) and HRR₂ (β_adjusted = 0.99, 95% CI 0.35-1.62; β_adjusted = 5.88, 95% CI 2.63-9.12). Moderate physical activity was not associated with HRR₁ (β_adjusted = 0.60, 95% CI -0.41 to 1.62), but was with HRR₂ (β_adjusted = 2.28, 95% CI 1.27-3.28). As free-living physical activity intensity increased, there was a greater association with HRR. This finding may provide mechanistic insight of previous research observations demonstrating intensity-specific effects of physical activity on various health outcomes.

Poor Heart Rate Recovery Is Associated With the Development of New-Onset Atrial Fibrillation in Middle-Aged Adults

OBJECTIVE

To investigate the association between heart rate recovery (HRR) and new-onset atrial fibrillation (AF) in middle-aged adults.

PATIENTS AND METHODS

Heart rate recovery was calculated using the exercise stress test in 15,729 apparently healthy self-referred men and women who attended periodic health screening examinations between January 2000, and December 2015. All participants completed the maximal exercise stress test according to the Bruce protocol and were followed clinically on a yearly basis for a median of 6.4±4 years. The primary end point was new-onset AF. Participants were grouped according to HRR at 5 minutes, dichotomized at the median value (<73 beats/min).

RESULTS

Participants with low HRR were older, were more commonly men, had a higher rate of comorbidities, and were less fit. Kaplan-Meier survival analysis revealed that the cumulative probability of AF at 6 years was higher in participants with low HRR (2.1%) than in those with high HRR (0.6%) (log-rank, P<.001). Older age, male sex, obesity resting heart rate, and ischemic heart disease were all associated with increased AF risk in a univariate Cox regression model (P<.05 for all). Multivariate Cox regression analysis revealed that low HRR was independently associated with increased AF risk (hazard ratio, 1.92; 95% CI, 1.3-2.8; P<.001) after adjustment for multiple confounders.

CONCLUSION

Lower HRR is independently associated with the development of new-onset AF during long-term follow-up in middle-aged adults.

Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association

Mounting evidence has firmly established that low levels of cardiorespiratory fitness (CRF) are associated with a high risk of cardiovascular disease, all-cause mortality, and mortality rates attributable to various cancers. A growing body of epidemiological and clinical evidence demonstrates not only that CRF is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus, but that the addition of CRF to traditional risk factors significantly improves the reclassification of risk for adverse outcomes. The purpose of this statement is to review current knowledge related to the association between CRF and health outcomes, increase awareness of the added value of CRF to improve risk prediction, and suggest future directions in research. Although the statement is not intended to be a comprehensive review, critical references that address important advances in the field are highlighted. The underlying premise of this statement is that the addition of CRF for risk classification presents health professionals with unique opportunities to improve patient management and to encourage lifestyle-based strategies designed to reduce cardiovascular risk. These opportunities must be realized to optimize the prevention and treatment of cardiovascular disease and hence meet the American Heart Association's 2020 goals.

Meta-Analysis of Prognostic Implications of Exercise-Induced Ventricular Premature Complexes in the General Population

Ventricular premature complexes (VPCs) during stress testing in the general population are commonly seen in clinical practice, but their prognostic value is not well understood. A comprehensive literature search of MEDLINE, Embase, and the Cochrane Library from January 1970 to May 2015 was conducted. Observational cohort studies on general populations evaluating the association between exercise-induced VPCs and all-cause or cardiovascular mortality were included in the analysis. Nine studies comprising 62,488 participants comparing clinical outcomes of patients with and without exercise-induced VPCs were included. The overall combined relative risks (RRs) for all-cause mortality and cardiovascular mortality in patients with exercise-induced VPCs were 1.41 (95% CI 1.23 to 1.61) and 1.86 (95% CI 1.51 to 2.30), respectively. In subgroup analysis, both frequent VPCs (RR 1.35, 95% CI 1.14 to 1.60) and infrequent VPCs (RR 1.57, 95% CI 1.13 to 2.18) were associated with an adverse outcome. VPCs during recovery were associated with an increased risk of death (RR 1.55, 95% CI 1.22 to 1.96). VPCs during exercise did not achieve statistical significance (RR 1.14, 95% CI 0.96 to 1.34), but only a few studies were included in the analysis. In conclusion, our meta-analysis suggests that exercise-induced VPCs in the general population significantly increase the risk of total mortality and cardiovascular mortality. Our study calls for further studies to assess the prognostic significance of exercise-induced VPCs and the utility of efforts to reduce the VPC burden to improve the clinical outcome.

Speed of Heart Rate Recovery in Response to Orthostatic Challenge

RATIONALE

Speed of heart rate recovery (HRR) may serve as an important biomarker of aging and mortality.

OBJECTIVE

To examine whether the speed of HRR after an orthostatic maneuver (ie, active stand from supine position) predicts mortality.

METHODS AND RESULTS

A longitudinal cohort study involving a nationally representative sample of community-dwelling older individuals aged ≥50 years. A total of 4475 participants completed an active stand at baseline as part of a detailed clinic-based cardiovascular assessment. Beat-to-beat heart rate and blood pressure responses to standing were measured during a 2-minute window using a finometer and binned in 10-s intervals. We modeled HRR to the stand by age group, cardiovascular disease burden, and mortality status using a random effects model. Mortality status during a mean follow-up duration of 4.3 years served as the primary end point (n=138). Speed of HRR in the immediate 20 s after standing was a strong predictor of mortality. A 1-bpm slower HRR between 10 and 20 s after standing increased the hazard of mortality by 6% controlling for established risk factors. A clear dose-response relationship was evident. Sixty-nine participants in the slowest HRR quartile died during the observation period compared with 14 participants in the fastest HRR quartile. Participants in the slowest recovery quartile were 2.3× more likely to die compared with those in the fastest recovery quartile.

CONCLUSIONS

Speed of orthostatic HRR predicts mortality and may aid clinical decision making. Attenuated orthostatic HRR may reflect dysregulation of the parasympathetic branch of the autonomic nervous system.

Exercise therapy improves aerobic capacity of inpatients with major depressive disorder

BACKGROUND

Unipolar depression is one of the most common diseases worldwide and is associated with a higher cardiovascular risk partly due to reduced aerobic capacity.

OBJECTIVES

Therefore, the aim of our study was to examine whether a structured aerobic training program can improve aerobic capacity in inpatients with MDD (major depressive disorder).

METHODS

Overall, 25 patients (13 women, 12 men) diagnosed with MDD were included in the study. Parameters of aerobic capacity, such as maximum performance, maximum oxygen consumption, and VAT (ventilatory anaerobic threshold), were assessed on a bicycle ergometer before and 6 weeks after a training period (three times per week for 45 min on two endurance machines). In addition, a constant load test was carried out at 50% of the maximum performance prior to and after the training period. The performance data were compared with 25 healthy controls matched for sex, age, and body mass index before and after the training period.

RESULTS

Compared to controls, patients with MDD had significantly lower aerobic capacity. After training, there was a significant improvement in their performance data. A significant difference remained only for VAT between patients with MDD and healthy controls.

CONCLUSION

With regard to the coincidence of MDD with cardiovascular and cardiometabolic disorders, a structured supervised exercise program carried out during hospitalization is a useful supplement for patients with MDD.

Impaired Heart Rate Response to Exercise in Diabetes and Its Long-term Significance

OBJECTIVE

To investigate the effect of diabetes mellitus on exercise heart rate and the role of impaired heart rate in excess mortality in diabetes.

PATIENTS AND METHODS

Patients without cardiovascular disease who underwent exercise testing from September 1, 1993, through December 31, 2010, were included. Mortality was determined from Mayo Clinic records and the Minnesota Death Index. Multivariate linear regression was used to compare heart rate responses in patients with vs without diabetes. Cox regression was used to determine the effect of abnormal heart rate recovery and abnormal chronotropic index on survival.

RESULTS

A total of 21,396 patients (65.4% men) with a mean ± SD age of 51±11 years, including 1200 patients with diabetes (5.4%), were included. Patients with diabetes had a higher resting heart rate (81±14 vs 77±13 beats/min), lower peak heart rate (154±20 vs 165±19 beats/min), heart rate reserve (73±19 vs 88±19 beats/min), chronotropic index (0.86±0.22 vs 0.99±0.20), and heart rate recovery (15±8 vs 19±9 beats/min) vs patients without diabetes. There were 1362 deaths (6.4%) during a mean ± SD follow-up of 11.9±4.9 years. Adjusting for age, sex, and heart rate-lowering drug use, a chronotropic index less than 0.8 contributed significantly to risk in patients with diabetes (hazard ratio [HR], 2.21; 95% CI, 1.62-3.00; P<.001) and patients without diabetes (HR, 1.94; 95% CI, 1.71-2.20; P<.001), as did abnormal heart rate recovery (patients with diabetes: HR, 2.21; 95% CI, 1.60-5.05; P<.001; patients without diabetes: HR, 1.75; 95% CI, 1.55-1.97).

CONCLUSIONS

Patients with diabetes exhibit abnormal heart rate responses to exercise, which are independently predictive of reduced long-term survival in patients with diabetes as in patients without diabetes.

Early-stage atherosclerosis in poloxamer 407-induced hyperlipidemic mice: pathological features and changes in the lipid composition of serum lipoprotein fractions and subfractions

Background

The aims of this study were to evaluate the effect of poloxamer 407 administration on atherogenic serum lipoprotein fractions and subfractions associated with cholesterol, triglycerides and phospholipids, as well as the onset of early atherosclerosis, in mice.

Methods

Mice were administered either sterile saline or poloxamer 407 (to induce a dose-controlled hyperlipidemia) for 1 month and then sacrificed at 1, 4 and 10 days after the last dose of poloxamer 407. Systolic and diastolic blood pressure, the activity of a cysteine protease (cathepsin B) in cardiac and liver tissue, and histological/morphological examination of heart and liver specimens was performed for each group of mice at each time point. Lastly, small angle X-ray scattering was utilized to analyze the lipoprotein fractions and subfractions associated with cholesterol, triglycerides and phospholipids for both groups of mice at each time point. Statistical analysis was performed using one-way, analysis-of-variance with post hoc analysis to determine significantly different mean values, while correlation analysis employed the Spearman test.

Results

Poloxamer 407-treated mice revealed significant hyperlipidemia, moderately elevated blood pressure, general lipidosis in liver cells, increased cysteine protease activity in heart tissue, and contractile-type changes in cardiomyocytes. Similar to humans, the onset of atherosclerosis in poloxamer 407-treated mice was characterized by a steady increase in serum low-density, intermediate-density and very-low-density lipoprotein fractions, as well as very-low-density lipoprotein subfractions.

Conclusions

We would propose that the sustained elevation of serum atherogenic lipoprotein fractions and subfractions induced by the administration of poloxamer 407 to mice resulted in the morphological changes we observed in both heart and liver cells, which are suggested to precede atherosclerosis, since this is a well-established mouse model of atherosclerosis. Since most of the cellular, biochemical and physiological changes documented in the present study using poloxamer 407-treated mice are related to the symptoms of early atherosclerosis in humans, it is suggested that the poloxamer 407-induced mouse model of hyperlipidemia and atherosclerosis might prove beneficial as an experimental animal model with which to evaluate the pathological features observed in early-stage atherosclerosis.

Resting heart rate and measures of effort-related cardiac autonomic dysfunction predict cardiovascular events in asymptomatic type 2 diabetes

BACKGROUND

Autonomic control of the cardiovascular system may be impaired in type 2 diabetes and is associated with increased morbidity and mortality. Parameters obtained during stress testing may reflect early stages of cardiac autonomic dysfunction and provide prognostic information in asymptomatic type 2 diabetes.

METHODS

We performed maximal exercise treadmill testing in 594 patients with type 2 diabetes without known coronary heart disease. The prognostic significance of physiological parameters associated with autonomic dysfunction was assessed, including chronotropic incompetence (<80% heart rate reserve), abnormal heart rate recovery at 1 minute <18 beats/minute, and resting tachycardia >100 beats/minute. Cox proportional hazards analysis was used to determine the association of exercise parameters with a composite outcome of all-cause mortality, myocardial infarction or stroke.

RESULTS

Resting heart rate >100 beats/minute was observed in 18% of patients, chronotropic incompetence in 30% and heart rate recovery at 1 minute <18 beats/minute in 35%. Over 79 ± 16 months, there were 72 (12%) events. Each parameter was significantly associated with event risk in an adjusted multivariate analysis: chronotropic incompetence (hazard ratio 1.89, 95% confidence interval 1.18-3.01; P = 0.008), resting heart rate ≥100 beats/minute (hazard ratio 1.97, 95% confidence interval 1.19-3.26; P = 0.008) and heart rate recovery at 1 minute <18 beats (hazard ratio 1.77, 95% confidence interval 1.12-2.81; P = 0.015). A progressive relationship between the number of abnormal parameters and event risk was observed (log rank P < 0.001).

CONCLUSIONS

Chronotropic incompetence, resting tachycardia and reduced heart rate recovery are independently and additively associated with long-term mortality, myocardial infarction or stroke in type 2 diabetes without known coronary heart disease.

Effects of Cydonia oblonga Miller leaf and fruit flavonoids on blood lipids and anti-oxydant potential in hyperlipidemia rats

OBJECTIVE

To study the effects of Cydonia oblonga Miller (COM) total flavonoids (TF) from leaves and fruit on the blood lipid and antioxidant potentials using hyperlipidaemic rat models.

METHODS

Hyperlipidaemic rat models were created with high-lipid emulsion. Rats were distributed into normal controls, hyperlipidaemic models, and daily high (160mg/kg), medium (80mg/kg) and low (40mg/kg) TF from leaves and fruit and simvastatin (5mg/kg) groups. After four weeks, serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), as well as hepatic superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) were measured.

RESULTS

Compared with the hyperlipidaemic model group, TF significantly reduced serum TC, TG, LDL-C (P<0.01), ALT and AST (P<0.01 or P<0.05) and increased HDL-C (P<0.05 or P<0.01). TF also reduced MDA (P<0.01 or P<0.01).

CONCLUSION

COM total flavonoids can effectively regulate the metabolism of lipids, and remove oxygen free radicals. This confirms its potential value in the prevention and treatment of hyperlipidaemia.

Effects of adjunctive exercise on physiological and psychological parameters in depression: a randomized pilot trial

OBJECTIVE

Major depressive disorder (MDD) is associated with decreased physical activity and increased rates of the metabolic syndrome (MetS), a risk factor for the development of type 2 diabetes and cardiovascular disorders. Exercise training has been shown to improve cardiorespiratory fitness and metabolic syndrome factors. Therefore, our study aimed at examining whether patients receiving an exercise program as an adjunct to inpatient treatment will benefit in terms of physiological and psychological factors.

METHOD

Fourty-two inpatients with moderate to severe depression were included. Twenty-two patients were randomized to additional 3x weekly exercise training (EXERCISE) and compared to treatment as usual (TAU). Exercise capacity was assessed as peak oxygen uptake (VO2peak), ventilatory anaerobic threshold (VAT) and workload expressed as Watts (W). Metabolic syndrome was defined according to NCEP ATPIII panel criteria.

RESULTS

After 6 weeks of treatment, cardiorespiratory fitness (VO2peak, VAT, Watt), waist circumference and HDL cholesterol were significantly improved in EXERCISE participants. Treatment response expressed as ≥50% MADRS reduction was more frequent in the EXERCISE group.

CONCLUSIONS

Adjunctive exercise training in depressed inpatients improves physical fitness, MetS factors, and psychological outcome. Given the association of depression with cardiometablic disorders, exercise training is recommended as an adjunct to standard antidepressant treatment.

Blood pressure morning surge, exercise blood pressure response and autonomic nervous system

OBJECTIVE

We investigated blood pressure (BP) response to exercise with respect to BP morning surge (MS), and the association between MS, exercise treadmill test (ETT) and heart rate variability (HRV) indices.

DESIGN

Eighty-four healthy subjects without hypertension were enrolled. Ambulatory BP monitoring and 24-hour Holter recordings were obtained for sleep-trough MS and HRV indices: low-frequency (LF) component, high-frequency (HF) component and LF/HF ratio. ETT was performed, and BPs were obtained at rest, end of each stage, and recovery. Third-minute heart rate recovery (HRR) and BP recovery ratio (BPRR) were calculated.

RESULTS

When analysed in quartiles of MS, systolic BP at low workloads was higher in the highest than in the lowest quartile, although maximum BPs at maximum exercise were not significantly different. BPRR was highest in the highest quartile in contrast to HRR, which was lowest in the highest quartile. LF/HF was highest during both at daytime and night-time in the highest quartile. BPRR and LF/HF were positively, and HRR was inversely associated with MS.

CONCLUSIONS

Subjects with a high MS have higher BP at low workloads, at which most daily activities are performed, and impairment in some indices, which indirectly reflect the autonomic nervous system.

Circulatory and Ventilatory Power: Characterization in Patients with Coronary Artery Disease

Background

Circulatory power (CP) and ventilatory power (VP) are indices that have been used for the clinical evaluation of patients with heart failure; however, no study has evaluated these indices in patients with coronary artery disease (CAD) without heart failure.

Objective

To characterize both indices in patients with CAD compared with healthy controls.

Methods

Eighty-seven men [CAD group = 42 subjects and healthy control group (CG) = 45 subjects] aged 40–65 years were included. Cardiopulmonary exercise testing was performed on a treadmill and the following parameters were measured: 1) peak oxygen consumption (VO₂), 2) peak heart rate (HR), 3) peak blood pressure (BP), 4) peak rate-pressure product (peak systolic HR x peak BP), 5) peak oxygen pulse (peak VO₂/peak HR), 6) oxygen uptake efficiency (OUES), 7) carbon dioxide production efficiency (minute ventilation/carbon dioxide production slope), 8) CP (peak VO₂ x peak systolic BP) and 9) VP (peak systolic BP/carbon dioxide production efficiency).

Results

The CAD group had significantly lower values for peak VO₂ (p < 0.001), peak HR (p < 0.001), peak systolic BP (p < 0.001), peak rate-pressure product (p < 0.001), peak oxygen pulse (p = 0.008), OUES (p < 0.001), CP (p < 0.001), and VP (p < 0.001) and significantly higher values for peak diastolic BP (p = 0.004) and carbon dioxide production efficiency (p < 0.001) compared with CG. Stepwise regression analysis showed that CP was influenced by group (R² = 0.44, p < 0.001) and VP was influenced by both group and number of vessels with stenosis after treatment (interaction effects: R² = 0.46, p < 0.001).

Conclusion

The indices CP and VP were lower in men with CAD than healthy controls.

Heart rate recovery and aerobic endurance capacity in cancer survivors: interdependence and exercise-induced improvements

PURPOSE

Whilst evidence supports beneficial effects of exercise on heart rate variability in cancer patients, its impact on heart rate recovery (HRR) and possible associations of exercise capacity and HRR have not yet been investigated. We aimed to evaluate the effects of an exercise intervention on HRR in relation to the baseline aerobic capacity.

METHODS

Cancer patients (n = 309, 178 females) performed a cardiopulmonary exercise test at baseline and at a 4-month interval follow-up with home-based and supervised exercise programs in-between. VO2 and heart rate were assessed during and HRR at 60 and 120 s after test termination. Based on a median split of the VO2 peak baseline values, participants were dichotomized into two groups: below median (47 female; 57.5 ± 10 years) and above median (48 female; 54.3 ± 12 years).

RESULTS

In the baseline sample (n = 309), VO2 peak correlated significantly with HRR60 (r = .327, p < .01) and HRR120 (r = .524, p < .01). For the compliers who completed intervention and assessments (n = 158), group comparisons demonstrated differences between below median versus above median group in absolute changes of HRR60 (3.1 ± 10.5 bpm (95% CI +0.6; +5.4) vs -1.8 ± 8.7 bpm (95% CI -3.7; +0.5)) and VO2 peak (2.9 ± 3.5 ml/kg/min (95% CI +2.1; +3.7) vs 0.66 ± 4 ml/kg/min (95% CI -0.6; +1.5)) (p < .01), but not in HRR120 (3.9 ± 11.8 bpm (95% CI +1.2; +6.6) vs 0.8 ± 10.8 bpm (95% CI -1.7; +3.5); p > .05).

CONCLUSIONS

These findings point toward a positive linear relationship between aerobic capacity and vagal reactivation in cancer patients. Patients with initial VO2 peak values below median showed improved VO2 peak, HRR60 and HRR120 following the moderate aerobic exercise intervention and differences to patients above median in all outcomes compared.

Cardiovascular recovery from psychological and physiological challenge and risk for adverse cardiovascular outcomes and all-cause mortality

OBJECTIVE

Exaggerated cardiovascular (CV) reactivity to laboratory challenge has been shown to predict future CV morbidity and mortality. CV recovery has been less studied and has yielded inconsistent findings, possibly due to the presence of moderators. Reviews on the relationship between CV recovery and CV outcomes have been limited to cross-sectional studies and have not considered methodological factors. We performed a comprehensive meta-analytic review of the prospective literature investigating CV recovery to physical and psychological challenge and adverse CV outcomes.

METHODS

We searched PsycINFO and PubMed for prospective studies investigating the relationship between CV recovery and adverse CV outcomes. Studies were coded for variables of interest and for effect sizes. We conducted a random-effects weighted meta-analysis. Moderators were examined with analysis of variance-analog and meta-regression analyses.

RESULTS

Thirty-seven studies met the inclusion criteria (n = 125,386). Impaired recovery from a challenge predicted adverse CV outcomes (summary effect, r = 0.17, p < .001). Physical challenge was associated with larger predictive effects than psychological challenge. Moderator analyses revealed that recovery measured at 1 minute postexercise, passive recovery, use of mortality as an outcome measure, and older sample age were associated with larger effects.

CONCLUSIONS

Poor recovery from laboratory challenges predicts adverse CV outcomes, with recovery from exercise serving as a particularly strong predictor of CV outcomes. The overall effect size for recovery and CV outcomes is similar to that observed for CV reactivity and suggests that the study of recovery may have incremental value for understanding adverse CV outcomes.

Predicting long-term cardiovascular risk using the mayo clinic cardiovascular risk score in a referral population

Exercise testing provides valuable information but is rarely integrated to derive a risk prediction model in a referral population. In this study, we assessed the predictive value of conventional cardiovascular risk factors and exercise test parameters in 6,546 consecutive adults referred for exercise testing, who were followed for a period of 8.1 ± 3.7 years for incident myocardial infarction, coronary revascularization, and cardiovascular death. A risk prediction model was developed, and cross-validation of model was performed by splitting the data set into 10 equal random subsets, with model fitting based on 9 of the 10 subsets and testing in of the remaining subset, repeated in all 10 possible ways. The best performing model was chosen based on measurements of model discrimination and stability. A risk score was constructed from the final model, with points assigned for the presence of each predictor based on the regression coefficients. Using both conventional risk factors and exercise test parameters, a total of 9 variables were identified as independent and robust predictors and were included in a risk score. The prognostic ability of this model was compared with that of the Adult Treatment Panel III model using the net reclassification and integrated discrimination index. From the cross-validation results, the c statistic of 0.77 for the final model indicated strong predictive power. In conclusion, we developed, tested, and internally validated a novel risk prediction model using exercise treadmill testing parameters.