Erratum to accuracy of wearable heart rate monitors in cardiac rehabilitation.

[This corrects the article DOI: 10.21037/cdt.2019.04.08.].

Accuracy of wearable heart rate monitors in cardiac rehabilitation.

BACKGROUND: To assess the accuracy of four wearable heart rate (HR) monitors in patients with established cardiovascular disease enrolled in phase II or III cardiac rehabilitation (CR). METHODS: Eighty adult patients enrolled in phase II or III CR were monitored during a CR session that included exercise on a treadmill and/or stationary cycle. Participants underwent HR monitoring with standard ECG limb leads, an electrocardiographic (ECG) chest strap monitor (Polar H7), and two randomly assigned wrist-worn HR monitors (Apple Watch, Fitbit Blaze, Garmin Forerunner 235, TomTom Spark Cardio), one on each wrist. HR was recorded at rest and at 3, 5, and 7 minutes of steady-state exercise on the treadmill and stationary cycle. RESULTS: Across all exercise conditions, the chest strap monitor (Polar H7) had the best agreement with ECG (rc=0.99) followed by the Apple Watch (rc=0.80), Fitbit Blaze (rc=0.78), TomTom Spark (rc=0.76) and Garmin Forerunner (rc=0.52). There was variability in accuracy under different exercise conditions. On the treadmill, only the Fitbit Blaze performed well (rc=0.76), while on the stationary cycle, Apple Watch (rc=0.89) and TomTom Spark (rc=0.85) were most accurate. CONCLUSIONS: In cardiac patients, the accuracy of wearable, optically based HR monitors varies, and none of those tested was as accurate as an electrode-containing chest monitor. This observation has implications for in-home CR, as electrode-containing chest monitors should be used when accurate HR measurement is imperative.

Cardiac rehabilitation: A class 1 recommendation.

Cardiac rehabilitation, consisting of prescribed exercise and counseling for risk modification, has proven benefits for patients with cardiovascular disease. Nevertheless, rates of referral and use remain low. Efforts to increase program referral and participation are ongoing.

Variable Accuracy of Wearable Heart Rate Monitors during Aerobic Exercise.

PURPOSE: Athletes and members of the public increasingly rely on wearable HR monitors to guide physical activity and training. The accuracy of newer, optically based monitors is unconfirmed. We sought to assess the accuracy of five optically based HR monitors during various types of aerobic exercise. METHODS: Fifty healthy adult volunteers (mean ± SD age = 38 ± 12 yr, 54% female) completed exercise protocols on a treadmill, a stationary bicycle, and an elliptical trainer (±arm movement). Each participant underwent HR monitoring with an electrocardiogaphic chest strap monitor (Polar H7), forearm monitor (Scosche Rhythm+), and two randomly assigned wrist-worn HR monitors (Apple Watch, Fitbit Blaze, Garmin Forerunner 235, and TomTom Spark Cardio), one on each wrist. For each exercise type, HR was recorded at rest, light, moderate, and vigorous intensity. Agreement between HR measurements was assessed using Lin's concordance correlation coefficient (rc). RESULTS: Across all exercise conditions, the chest strap monitor (Polar H7) had the best agreement with ECG (rc = 0.996) followed by the Apple Watch (rc = 0.92), the TomTom Spark (rc = 0.83), and the Garmin Forerunner (rc = 0.81). Scosche Rhythm+ and Fitbit Blaze were less accurate (rc = 0.75 and rc = 0.67, respectively). On treadmill, all devices performed well (rc = 0.88-0.93) except the Fitbit Blaze (rc = 0.76). While bicycling, only the Garmin, Apple Watch, and Scosche Rhythm+ had acceptable agreement (rc > 0.80). On the elliptical trainer without arm levers, only the Apple Watch was accurate (rc = 0.94). None of the devices was accurate during elliptical trainer use with arm levers (all rc < 0.80). CONCLUSION: The accuracy of wearable, optically based HR monitors varies with exercise type and is greatest on the treadmill and lowest on elliptical trainer. Electrode-containing chest monitors should be used when accurate HR measurement is imperative.

Variables Measured During Cardiopulmonary Exercise Testing as Predictors of Mortality in Chronic Systolic Heart Failure.

BACKGROUND: Data from a cardiopulmonary exercise (CPX) test are used to determine prognosis in patients with chronic heart failure (HF). However, few published studies have simultaneously compared the relative prognostic strength of multiple CPX variables. OBJECTIVES: The study sought to describe the strength of the association among variables measured during a CPX test and all-cause mortality in patients with HF with reduced ejection fraction (HFrEF), including the influence of sex and patient effort, as measured by respiratory exchange ratio (RER). METHODS: Among patients (n = 2,100, 29% women) enrolled in the HF-ACTION (HF-A Controlled Trial Investigating Outcomes of exercise traiNing) trial, 10 CPX test variables measured at baseline (e.g., peak oxygen uptake [Vo2], exercise duration, percent predicted peak Vo2 [%ppVo2], ventilatory efficiency) were examined. RESULTS: Over a median follow-up of 32 months, there were 357 deaths. All CPX variables, except RER, were related to all-cause mortality (all p < 0.0001). Both %ppVo2 and exercise duration were equally able to predict (Wald chi-square: ∼141) and discriminate (c-index: 0.69) mortality. Peak Vo2 (ml·kg(-1)·min(-1)) was the strongest predictor of mortality among men (Wald chi-square: 129) and exercise duration among women (Wald chi-square: 41). Multivariable analyses showed that %ppVo2, exercise duration, and peak Vo2 (ml·kg(-1)·min(-1)) were similarly able to predict and discriminate mortality. In men, a 10% 1-year mortality rate corresponded to a peak Vo2 of 10.9 ml·kg(-1)·min(-1) versus 5.3 ml·kg(-1)·min(-1) in women. CONCLUSIONS: Peak Vo2, exercise duration, and % ppVo2 carried the strongest ability to predict and discriminate the likelihood of death in patients with HFrEF. The prognosis associated with a given peak Vo2 differed by sex. (Exercise Training Program to Improve Clinical Outcomes in Individuals With Congestive Heart Failure; NCT00047437).

Asymmetrical pedaling patterns in Parkinson's disease patients.

BACKGROUND: Approximately 1.5 million Americans are affected by Parkinson's disease (Deponti et al., 2013) which includes the symptoms of postural instability and gait dysfunction. Currently, clinical evaluations of postural instability and gait dysfunction consist of a subjective rater assessment of gait patterns using items from the Unified Parkinson's Disease Rating Scale, and assessments can be insensitive to the effectiveness of medical interventions. Current research suggests the importance of cycling for Parkinson's disease patients, and while Parkinson's gait has been evaluated in previous studies, little is known about lower extremity control during cycling. The purpose of this study is to examine the lower extremity coordination patterns of Parkinson's patients during cycling. METHODS: Twenty five participants, ages 44-72, with a clinical diagnosis of idiopathic Parkinson's disease participated in an exercise test on a cycle ergometer that was equipped with pedal force measurements. Crank torque, crank angle and power produced by right and left leg were measured throughout the test to calculate Symmetry Index at three stages of exercise (20 W, 60 W, maximum performance). FINDINGS: Decreases in Symmetry Index were observed for average power output in Parkinson's patients as workload increased. Maximum power Symmetry Index showed a significant difference in symmetry between performance at both the 20 W and 60 W stage and the maximal resistance stage. Minimum power Symmetry Index did not show significant differences across the stages of the test. While lower extremity asymmetries were present in Parkinson's patients during pedaling, these asymmetries did not correlate to postural instability and gait dysfunction Unified Parkinson's Disease Rating Scale scores. INTERPRETATION: This pedaling analysis allows for a more sensitive measure of lower extremity function than the Unified Parkinson's Disease Rating Scale and may help to provide unique insight into current and future lower extremity function.

Effects of exercise training on depressive symptoms in patients with chronic heart failure: the HF-ACTION randomized trial.

CONTEXT: Depression is common in patients with cardiac disease, especially in patients with heart failure, and is associated with increased risk of adverse health outcomes. Some evidence suggests that aerobic exercise may reduce depressive symptoms, but to our knowledge the effects of exercise on depression in patients with heart failure have not been evaluated. OBJECTIVE: To determine whether exercise training will result in greater improvements in depressive symptoms compared with usual care among patients with heart failure. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, randomized controlled trial involving 2322 stable patients treated for heart failure at 82 medical clinical centers in the United States, Canada, and France. Patients who had a left ventricular ejection fraction of 35% or lower, had New York Heart Association class I to IV heart failure, and had completed the Beck Depression Inventory II (BDI-II) score were randomized (1:1) between April 2003 and February 2007. Depressive scores ranged from 0 to 59; scores of 14 or higher are considered clinically significant. INTERVENTIONS: Participants were randomized either to supervised aerobic exercise (goal of 90 min/wk for months 1-3 followed by home exercise with a goal of ≥120 min/wk for months 4-12) or to education and usual guideline-based heart failure care. MAIN OUTCOME MEASURES: Composite of death or hospitalization due to any cause and scores on the BDI-II at months 3 and 12. RESULTS: Over a median follow-up period of 30 months, 789 patients (68%) died or were hospitalized in the usual care group compared with 759 (66%) in the aerobic exercise group (hazard ratio [HR], 0.89; 95% CI, 0.81 to 0.99; P = .03). The median BDI-II score at study entry was 8, with 28% of the sample having BDI-II scores of 14 or higher. Compared with usual care, aerobic exercise resulted in lower mean BDI-II scores at 3 months (aerobic exercise, 8.95; 95% CI, 8.61 to 9.29 vs usual care, 9.70; 95% CI, 9.34 to 10.06; difference, -0.76; 95% CI,-1.22 to -0.29; P = .002) and at 12 months (aerobic exercise, 8.86; 95% CI, 8.67 to 9.24 vs usual care, 9.54; 95% CI, 9.15 to 9.92; difference, -0.68; 95% CI, -1.20 to -0.16; P = .01). CONCLUSIONS: Compared with guideline-based usual care, exercise training resulted in a modest reduction in depressive symptoms, although the clinical significance of this improvement is unknown. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00047437.

Modest increase in peak VO2 is related to better clinical outcomes in chronic heart failure patients: results from heart failure and a controlled trial to investigate outcomes of exercise training.

BACKGROUND: The prognostic ability of a single measurement of peak oxygen uptake (VO(2)) is well established in patients with chronic heart failure. The relation between a change in peak VO(2) and clinical outcomes is not well defined. METHODS AND RESULTS: This investigation determined whether an increase in peak VO(2) was associated with a lower risk of the primary end point of time to all-cause mortality or all-cause hospitalization and 3 secondary end points. In Heart Failure and a Controlled Trial to Investigate Outcomes of Exercise Training, an exercise training trial for patients with systolic heart failure, cardiopulmonary exercise tests were performed at baseline and ≈3 months later in 1620 participants. Median peak VO(2) in the combined sample increased from 15.0 (11.9-18.0 Q1-Q3) to 15.4 (12.3-18.7 Q1-Q3) mL·kg(-1)·min(-1). Every 6% increase in peak VO(2,) adjusted for other significant predictors, was associated with a 5% lower risk of the primary end point (hazard ratio=0.95; CI=0.93-0.98; P<0.001); a 4% lower risk of the secondary end point of time to cardiovascular mortality or cardiovascular hospitalization (hazard ratio=0.96; CI=0.94-0.99; P<0.001); an 8% lower risk of cardiovascular mortality or heart failure hospitalization (hazard ratio=0.92; CI=0.88-0.96; P<0.001); and a 7% lower all-cause mortality (hazard ratio=0.93; CI=0.90-0.97; P<0.001). CONCLUSIONS: Among patients with chronic systolic heart failure, a modest increase in peak VO(2) over 3 months was associated with a more favorable outcome. Monitoring the change in peak VO(2) for such patients may have benefit in assessing prognosis.

Predictors of women's exercise maintenance after cardiac rehabilitation.

PURPOSE: Less than 50% of persons who participate in cardiac rehabilitation (CR) programs maintain an exercise regimen for as long as 6 months after completion. This study was conducted to identify factors that predict women's exercise following completion of a CR program. METHODS: In this prospective, descriptive study, a convenience sample of 60 women were recruited at completion of a phase II CR program. Exercise was measured using a heart rate wristwatch monitor over 3 months. Predictor variables collected at the time of the subjects' enrollment were age, body mass index, cardiac functional status, comorbidity, muscle or joint pain, motivation, mood state, social support, self-efficacy, perceived benefits or barriers, and prior exercise. RESULTS: Of women, 25% did not exercise at all following completion of a CR program and only 48% of the subjects were exercising at 3 months. Different predictors were found of the various dimensions of exercise maintenance. Predictors of exercise frequency were comorbidity and instrumental social support. Instrumental social support was the only predictor of exercise persistence. Comorbidity was the only predictor of exercise intensity. The only predictor of the total amount of exercise was benefits or barriers. CONCLUSIONS: Interventions aimed at increasing women's exercise should focus on increasing their problem-solving abilities to reduce barriers to exercise and increase social support by family and friends. Because comorbidity was a significant predictor of exercise, women should be encouraged to use exercise techniques that reduce impact on muscles and joints (eg, swimming) or exercising for short periods several times a day.