Chronotropic Index Research Articles

The Clinical Use of Nonimaging Exercise Stress Testing

Exercise stress testing is an exceptionally useful cardiovascular test providing a wealth of information that can be used in patient management. It can be used in the diagnosis and/or management of chest pain, hypertension, arrhythmia, and heart failure. Non-imaging exercise stress testing not only helps evaluate the etiology of clinical symptoms but also provides an opportunity to evaluate ECG changes with exercise, total exercise capacity, heart rate response or chronotropic index, blood pressure response, heart rate recovery, and to make estimates of the risk of coronary artery disease using tools such as the Duke Treadmill Score. These parameters, individually and collectively, provide valuable information on the likelihood of disease and an individual’s prognosis. In addition, exercise testing is inexpensive, quick and widely available compared to imaging studies. This review contains 6 figures, 5 tables, and 68 references. Keywords: blood pressure response, chronotropic incompetence, coronary artery disease, Duke Treadmill Score, exercise physiology metabolic equivalents (METs), exercise stress test, exercise treadmill test, exercise-induced hypertension, heart rate recovery, maximal exercise capacity, ST-segment deviation

Exercise chronotropic incompetence phenotypes the level of cardiovascular risk and exercise gas exchange impairment in the general population. An analysis of the Euro-EX prevention trial.

Chronotropic insufficiency (CI) is defined as the inability of the heart to increase its rate commensurate with increased demand. Exercise CI is an established predictor of major adverse cardiovascular events in patients with cardiovascular diseases. The aim of this study was to evaluate how exercise CI phenotypes different levels of cardiovascular risk and how it may better perform in defining cardiovascular risk when analysed in the context of cardiopulmonary exercise test (CPET)-derived measures and standard echocardiography in a healthy population with variable cardiovascular risk profile. Apparently healthy individuals (N = 702, 53.8% females) with at least one major cardiovascular risk factor (MCVRF; hypertension, diabetes, tabagism, dyslipidaemia, body mass index > 25), enrolled in the Euro-EX prevention trial, underwent CPET. CI was defined as the inability to reach 80% of the chronotropic index, that is, the ratio of peak heart rate - rest heart rate/peak heart rate - age predicted maximal heart rate (AMPHR: 220 - age), they were divided into four groups according to the heart rate reserve (<80%>) and respiratory gas exchange ratio (RER; < 1.05>) as a marker of achieved maximal performance. Subjects with a RER < 1.05 (n = 103) were excluded and the final population (n = 599) was divided into CI group (n = 472) and no-CI group (n = 177). Compared with no-CI, CI subjects were more frequently females with a history of hypertension in a high rate. CI subjects also exhibited a significantly lower peak oxygen uptake (VO2) and circulatory power and an echocardiographic pattern indicative of higher left atrial volume index and left ventricular mass index. An inverse stepwise relationship between heart rate reserve and number of MCVRFs was observed (one MCVRF: 0.71 ± 0.23; two MCVRFs: 0.68 ± 0.24, three MCVRFs: 0.64 ± 0.20; four MCVRFs: 0.64 ± 0.23; five MCVRFs: 0.57 ± 18; p < 0.01). In multivariate analysis the only variable found predicting CI was peak VO2 (p < 0.05; odds ratio 0.91; confidence interval 0.85-0.97). In a population of apparently healthy subjects, exercise CI is common and phenotypes the progressive level of cardiovascular risk by a tight relationship with MCVRFs. CI patients exhibit some peculiar abnormal exercise gas exchange patterns (lower peak VO2 and exercise oscillatory ventilation) and echo-derived measures (higher left atrium size and left ventricle mass) that may well anticipate evolution toward heart failure.

Impaired cardiac autonomic response in lung transplant patients: A retrospective cohort study.

Cardiac autonomic dysfunction (AD) is associated with adverse prognosis in lung disease; however, its implications in lung transplantation have not been previously described. This study evaluated the prevalence of AD in lung transplant (LTx) candidates, its determinants, prognostic implications, and prevalence post-transplant. Retrospective one-year study of 103 LTx candidates with AD assessed using heart rate (HR) from the six-minute walk test (6MWT). Impaired chronotropic response index (CRI) was defined as <80% age-adjusted HR during 6MWT. Abnormal HR recovery (HRR) was categorized as reduction in HR≤12 beats/minute after the first minute of 6MWT cessation. Abnormal CRI and HRR were observed in 94% and 76% of patients, respectively. A lower CRI was associated with obstructive lung disease and lower estimated aerobic capacity. CRI was independently associated with 6MW distance [12m per 10% CRI, P=0.03], but not with post-transplant cardiovascular events, hospital stay, or one-year mortality. At 3months post-transplant, no improvement was observed in CRI (99%, n=66/67, P=0.25) or HRR (88%, n=36/41, P=0.12). Cardiac AD was prevalent in LTx candidates and recipients, with chronotropic incompetence a modest contributor to exercise intolerance pretransplant. Further study may help determine whether direct autonomic measures such as HR variability may be more prognostic of LTx outcomes.

EFFECT OF A SINGLE TRANSCRANIAL STIMULATION ON THE RECOVERY OF SKI-RACERS

Aim. The article deals with assessing the effect of a single transcranial stimulation with impulse current on the recovery of ski-racers. Materials and methods. 18 skiers aged 20 ± 2 (skiers of the first rank or that of Candidate of Master of Sport) participated in the study. Skiing for 3 was used as a special load. To achieve the purpose of the study, we used the method of transcranial stimulation with impulse current after load. Results. During a single transcranial stimulation after a special load by the 20th minute, there is a statistically significant reduction of the urgent recovery of heart rate (HR), minute blood volume (MBV), the Robinson index (RI), the chronotropic index (CI). The time for the recovery of vegetative homeostasis also reduces. Conclusion. A single transcranial stimulation accelerates the recovery of the cardiovascular system in ski-racers by reducing the adrenergic effects of the autonomic nervous system. The efficiency of using transcranial stimulation is associated with individual-typological features of the vegetative regulation in athletes.

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.

Heart Rate Response During Treadmill Exercise Test in Children and Adolescents With Congenital Heart Disease.

Background: Impaired exercise capacity is a common feature of congenital heart disease (CHD). In adults with CHD, it has been shown that impaired heart rate response during exercise may contribute to exercise limitation. Systematic data in children and adolescents on this topic is limited. We therefore purposed to assess heart rate response during treadmill exercise testing in children and adolescents with CHD compared to healthy controls.Methods: One hundred and sixty three children and adolescents (103 with CHD, median age 15 years and 60 age-matched controls) performed cardiopulmonary exercise testing and were included in this study. Beyond peak oxygen consumption, increase in heart rate from resting level to peak exercise (heart rate reserve) and decrease of heart rate after peak exercise (heart rate recovery) were measured. Chronotropic index was defined as percentage of age predicted maximal heart rate reserve. According to data from adults on bicycle exercise, chronotropic incompetence was assumed for chronotropic index below 0.8.Results: While resting heart rate was similar between both groups, peak heart rate, heart rate reserve as well as chronotropic index were lower in the CHD group than in controls. Chronotropic index was lowest in patients with single ventricle hemodynamics and correlated with peak oxygen consumption. Heart rate recovery was impaired in the CHD group 1 and 2 min after peak exercise compared to controls and correlated with peak oxygen consumption. Chronotropic index below 0.8 was a relatively frequent finding even in the control group suggesting that the threshold of 0.8 appears inadequate for the identification of chronotropic incompetence using treadmill exercise testing in children. After normalizing to the 2.5th chronotropic index percentile of the control group we obtained a chronotropic incompetence threshold of 0.69.Conclusion: As an adjunct to measurement of peak oxygen consumption, heart rate response to exercise appears to be a physiologically important diagnostic parameter in children and adolescents with CHD. However, interpretation of heart rate response needs to consider specific age characteristics and the mode of exercise test. Our data may help future studies on chronotropic incompetence using treadmill ergometer protocols in children and adolescents.

Estimated age based on exercise stress testing performance outperforms chronological age in predicting mortality.

We sought to estimate patients' age based on their stress testing exercise performance (A-BEST), and evaluate whether A-BEST would be a better predictor of mortality when compared to chronological age. We included 126,356 consecutive patients referred for exercise (electrocardiography, echocardiography or myocardial perfusion imaging) stress testing at our institution from January 1st, 1991 to February 27th, 2015. Estimated age was computed based on exercise capacity (number of peak estimated metabolic equivalents of task), chronotropic reserve index and heart rate recovery, taking into account patient's gender and medications that affect heart rate. Uni and multivariable Cox models were used to determine the association of A-BEST with mortality. Improvement in predicting mortality using A-BEST compared to chronological age was evaluated with the use of net reclassification improvement and C statistic. Mean age was 53.5 ± 12.6 years and 59% were men. At follow-up (mean duration was 8.7 years), 9929 (8%) died. After adjustment for clinical comorbidities, higher metabolic equivalents of task (adjusted hazard ratio (HR) for mortality 0.71, 95% confidence interval (CI) 0.70-0.72, P < 0.001) and higher chronotropic reserve index (adjusted HR for mortality 0.97, 95% CI 0.96-0.99, P = 0.0135) were associated with improved survival, whereas abnormal heart rate recovery (adjusted HR for mortality 1.53, 95% CI 1.46-1.61, P < 0.001) and higher A-BEST (adjusted HR for mortality 1.05, 95% CI 1.04-1.05, P < 0.001) were associated with higher mortality. When comparing prediction models using A-BEST versus chronological age, a significant increase in the area under the curve was demonstrated if A-BEST was used (0.82 vs. 0.79, P < 0.001). The overall net reclassification improvement was 0.30 ( P < 0.001). Estimated age based on exercise stress testing performance is a better predictor of mortality when compared to chronological age.

Non Electrocardiographic alterations in exercise testing in asymptomatic women. Associations with cardiovascular risk factors

OBJECTIVES:To estimate the prevalence of exercise testing alterations in middle-aged women without symptoms of heart disease and to verify the associations of functional capacity and heart rate behavior during and after exercise with cardiovascular risk factors.METHODS:A cross-sectional study was conducted with 509 asymptomatic women aged between 46 and 65 years who underwent clinical evaluations and exercise testing (Bruce protocol). The heart rate behavior was evaluated by the maximal predicted heart rate achieved, chronotropic index and recovery heart rate.RESULTS:The mean age was 56.4±4.8 years, and 13.4% of the patients had a Framingham risk score above 10%. In the exercise treadmill testing, 58.0% presented one or more of the following alterations (listed in order of ascending prevalence): symptoms (angina, dyspnea, and dizziness), ST-segment depression, arrhythmia, reduction in recovery heart rate of ≤12 bpm at 1 minute, altered maximal predicted heart rate achieved, abnormal blood pressure, functional capacity deficiency, and altered chronotropic index. In the multivariate analysis, the following associations (odds ratio) were observed for these alterations: chronotropic index was associated with obesity (2.08) and smoking (4.47); maximal predicted heart rate achieved was associated with smoking (6.45); reduction in the recovery heart rate at 1 minute was associated with age (1.09) and obesity (2.78); functional capacity was associated with age (0.92), an overweight status (2.29) and obesity (6.51).CONCLUSIONS:More than half of middle-aged women without cardiovascular symptoms present alterations in one or more exercise testing parameters. Alterations in the functional capacity or heart rate behavior, as verified by exercise testing, are associated with age, smoking, an overweight status and obesity.

Resting Heart Rate and Chronotropic Response to Exercise: Prognostic Implications in Heart Failure Across the Left Ventricular Ejection Fraction Spectrum

We studied the relationship between resting heart rate (HR), chronotropic response to exercise, and clinical outcomes in patients with heart failure (HF) across the spectrum of left ventricle ejection fraction (LVEF). Resting HR and chronotropic index (CIx) were assessed in 718 patients with HF (53 ± 14 years of age, 66% male) referred for exercise testing. Associations with the composite outcome of left ventricular assist device implantation, transplantation, or death (151 events, 4.4 [range 3.0-5.8] years of follow-up) were assessed with the use of Cox models adjusted for age, sex, HF etiology, diabetes, LVEF, beta-blocker use, device therapy, estimated glomerular filtration rate, and peak oxygen uptake. Resting HR was 73 ± 15 beats/min, CIx was 0.60 ± 0.26, LVEF was 34% ± 15%, and 39% had an LVEF ≥40%. Resting HR correlated poorly with CIx (r = 0.08; P = .04) and did not predict (P = .84) chronotropic incompetence (CIx <0.60). Both higher resting HR (per 5 beats/min increase: adjusted hazard ratio [HR] -1.05, 95% confidence interval [CI] 1.00-1.11) and CIx (per SD change: adjusted HR -0.77, 95% CI 0.62-0.94) were independent prognostic markers. No heterogeneity of effect was noted based on LVEF (P >.05). Higher resting HR and lower CIx are both associated with more severe HF, but correlated poorly with each other. They provide independent and additive prognostic information in HF across the LVEF spectrum.

Increased cardiac stiffness is associated with autonomic dysfunction in patients with temporal lobe epilepsy.

Autonomic dysfunction is linked to sudden death regardless of the presence of structural heart disease. The pathway from autonomic dysfunction to sudden death is not fully understood, but myocardial sympathetic stimulation leading to arrhythmia and/or cardiac fibrosis might play a role. Our goal was to evaluate cardiac stiffness by echocardiography and its association with clinical, structural, and autonomic variables in people with epilepsy (PWE) compared to healthy controls. A 12-lead electrocardiogram, treadmill testing, and transthoracic echocardiography from 30 patients with temporal lobe epilepsy (TLE) without any known cardiovascular disorders were compared to 30 individuals without epilepsy matched by sex, age, and body mass index. Distribution of cardiovascular risk factors was similar in both groups. PWE had a higher left ventricle stiffness, left ventricle filling pressure, and greater left atrial volume as well as markers of autonomic dysfunction such as impaired chronotropic index and percentage achieved of predicted peak heart rate at effort. In multiple regressions, autonomic dysfunction explained 52% of stiffness and carbamazepine treatment and polytherapy with antiepileptic drugs (AEDs) explained, additionally, 6% each. Stiffness is increased in young patients with TLE and is related to autonomic dysfunction and to a lesser extent, carbamazepine use and polytherapy with AEDs.

Acute Sildenafil Treatment Improves Exercise Capacity in Patients with Cystic Fibrosis

BackgroundExercise capacity has been shown to predict quality of life, mortality, and risk for hospitalization in patients with Cystic Fibrosis (CF). Many patients with CF exhibit exercise intolerance, the mechanism of which has yet to be elucidated. Sildenafil, a phosphodiesterase type 5 inhibitor, increases blood flow and therefore may improve exercise capacity in patients with CF.PurposeThe purpose of this study was to determine whether an acute dose of sildenafil improves exercise capacity in patients with CF.Methods13 patients with CF (mean age = 25 ± 10 years) participated in a double blind, randomized, placebo controlled study. Exercise capacity utilizing the Godfrey Protocol on a cycle ergometer was assessed at baseline and 1 hour following treatment with either sildenafil (50 mg) or placebo.ResultsA significantly greater increase (p = 0.024) in VO2 peak was observed following sildenafil treatment (4.16 ± 1.54 ml/kg/FFM) compared to placebo (1.09 ± 1.31 ml/kg/FFM). The change in maximal heart rate during exercise was statistically (p = 0.007) greater following sildenafil treatment (6.07 ± 4.04 bpm) compared to placebo (−1.54 ± 6.06 bpm). The change in chronotropic index (CRI) was significantly (p = 0.006) higher following sildenafil treatment (0.08 ± 0.02) compared with placebo (0.04 ± 0.02).Conclusion/InterpretationThese findings suggest that an acute dose of sildenafil improves exercise capacity in patients with CF. In addition, treatment with sildenafil improved CRI. Future studies should focus on elucidating the mechanisms for improvement in exercise capacity and CRI as both are predictors of mortality.Support or Funding InformationSupported in part by the Medical College of Georgia's Medical Scholar Program and the Laboratory of Integrative Vascular and Exercise Physiology.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Heart rate response and functional capacity in patients with chronic heart failure with preserved ejection fraction.

AimsThe mechanisms of exercise intolerance in heart failure with preserved ejection fraction (HFpEF) are not yet elucidated. Chronotropic incompetence has emerged as a potential mechanism. We aimed to evaluate whether heart rate (HR) response to exercise is associated to functional capacity in patients with symptomatic HFpEF.Methods and resultsWe prospectively studied 74 HFpEF patients [35.1% New York Heart Association Class III, 53% female, age (mean ± standard deviation) 72.5 ± 9.1 years, and 59.5% atrial fibrillation]. Functional performance was assessed by peak oxygen consumption (peak VO2). The mean (standard deviation) peak VO2 was 10 ± 2.8 mL/min/kg. The following chronotropic parameters were calculated: Delta‐HR (HR at peak exercise − HR at rest), chronotropic index (CI) = (HR at peak exercise − resting HR)/[(220 − age) − resting HR], and CI according to the equation developed by Keteyian et al. (CIK) (HR at peak exercise − HR at rest)/[119 + (HR at rest/2) − (age/2) − 5 − HR at rest]. In a bivariate setting, peak VO2 was positively and significantly correlated with Delta‐HR (r = 0.35, P = 0.003), CI (r = 0.27, P = 0.022), CIK (r = 0.28, P = 0.018), and borderline with HR at peak exercise (r = 0.22, P = 0.055). In a multivariable linear regression analysis that included clinical, analytical, echocardiographic, and functional capacity covariates, the chronotropic parameters were positively associated with peak VO2. We found a linear relationship between Delta‐HR and peak VO2 (β coefficient of 0.03; 95% confidence interval: 0.004–0.05; P = 0.030); conversely, the association among CIs and peak VO2 was exponentially shaped.ConclusionsIn patients with chronic HFpEF, the HR response to exercise was positively associated to patient's functional capacity.

Myocardial Infarction Injury in Patients with Chronic Lung Disease Entering Pulmonary Rehabilitation: Frequency and Association with Heart Rate Parameters

BackgroundMyocardial infarction (MI) remains under-recognized in chronic lung disease (CLD) patients. Rehabilitation health professionals need accessible clinical measurements to identify the presence of prior MI in order to determine appropriate training prescription. ObjectivesTo estimate prior MI in CLD patients entering a pulmonary rehabilitation program, as well as its association with heart rate parameters such as resting heart rate and chronotropic response index. DesignRetrospective cohort design. SettingPulmonary rehabilitation outpatient clinic in a tertiary care university-affiliated hospital. PatientsEighty-five CLD patients were studied. MethodsElectrocardiograms at rest and peak cardiopulmonary exercise testing, performed before pulmonary rehabilitation, were analyzed. Electrocardiographic evidence of prior MI, quantified by the Cardiac Infarction Injury Score (CIIS), was contrasted with reported myocardial events and then correlated with resting heart rate and chronotropic response index parameters. Main outcome measurementsCIIS, resting heart rate, and chronotropic response index. ResultsSixteen CLD patients (19%) demonstrated electrocardiographic evidence of prior MI, but less than half (8%) had a reported MI history (P < .05). The Cohen’s kappa test revealed poor level of agreement between CIIS and medical records (kappa = 0.165), indicating that prior MI diagnosis was under-reported in the medical records. Simple and multiple regression analyses showed that resting heart rate but not chronotropic response index was positively associated with CIIS in our population (R2 = 0.29, P < .001). CLD patients with a resting heart rate higher than 80 beats/min had approximately 5 times higher odds of having prior MI, as evidenced by a CIIS ≥ 20. ConclusionsCLD patients entering pulmonary rehabilitation are at risk of unreported prior MI. Elevated resting heart rate appears to be an indicator of prior MI in CLD patients; therefore, careful adjustment of training intensity is recommended under these circumstances. Level of EvidenceIII

EXERCISE AGE OUTPERFORMS CHRONOLOGIC AGE IN PREDICTING MORTALITY IN PATIENTS WITHOUT KNOWN CORONARY DISEASE

Exercise capacity [peak estimated metabolic equivalents of task (METs)], abnormal heart rate recovery (AHRR), and chronotropic reserve index (CRI) are among the strongest predictors of mortality. We sought to estimate “exercise age” (EA) based on these variables and compare it to chronologic age

Intrauterine growth restriction is not associated with decreased exercise capacity in adolescents with congenital heart disease.

Multiple studies demonstrate the association of intrauterine growth restriction (IUGR) with impaired aerobic fitness in adolescents and adults. To our knowledge, there are no studies including individuals with the history of both IUGR and congenital heart disease (CHD). Thus, we sought to evaluate the impact of IUGR on exercise capacity in adolescents with CHD. We conducted a retrospective chart review of patients <18 years of age who underwent cardiopulmonary exercise testing (CPET) between August 1, 2003 and July 1, 2016. Individuals with birth weight <10th percentile for gestational age were defined as IUGR. Patients with IUGR were matched with non-IUGR patients by cardiac diagnosis and age at CPET. We excluded patients >18 years of age at time of CPET, those without a documented birth weight, gestational age, or Race. A total of 282 patients were included with CHD present in 86 IUGR cases and 86 controls. There was no difference in percent predicted exercise duration (IUGR: 65.2% ± 31.2, non-IUGR: 67.4% ± 27.2; P = .67). Resting heart rate, chronotropic index, percent-predicted peak oxygen consumption, and pulmonary function were similar between groups. Regression analyses confirmed that IUGR was not independently associated with difference in percent-predicted exercise duration. Intrauterine growth restriction is not associated with the differences in the measurements of exercise capacity in adolescents with CHD. These findings contrast earlier studies, showing decreased fitness in individuals with low birth weight but without CHD. To our knowledge, this is the first study to examine the impact of IUGR on exercise capacity in patients with CHD.

Can chronotropic incompetence predict life-threatening ventricular arrhythmias in patients with stable ischemic heart disease?

Background:Chronotropic incompetence has prognostic value of all-cause and cardiovascular mortality in both patients with asymptomatic and symptomatic ischemic heart disease (IHD), regardless of traditional risk factors. The aim of this study was to investigate the relationship between chronotropic response during exercise test and the development of ventricular arrhythmias.Methods:153 patients with stable ischemic heart disease were screened and observed during the 24 months since October 2014 in a university hospital in Astana Kazakhstan. They underwent bedside electrocardiography, 24h heart rate Holter monitoring, echocardiography, exercise stress test (treadmill) for assessment of chronotropic index calculating at first contact. Holter- electrocardiography was repeated three times (at 3, 6, 12 months of follow-up period) to reveal life-threatening ventricular arrhythmias.Results:The quantity of the ventricular extrasystoles was higher in the group with low chronotropic index. Low chronotropic index increased the risk of high grade ventricular extrasystoles more than two times (P=0.015); episodes of non-sustained VT more than three times (p<0.001); and episodes of sustained VT more than nine times (p<0.001).Conclusions:Chronotropic index less than 35.6 increases the risk for life-threatening ventricular arrhythmias in patients with stable chronicle ischemic heart disease irrespectively of severe left ventricle systolic dysfunction.

Heart rate response to graded exercise test of elderly subjects in different ranges of TSH levels.

Life expectancy is increasing worldwide and studies have been demonstrating that elevated serum thyroid stimulating hormone (TSH) concentration in elderly is associated with some better health outcomes. This elevation is somewhat physiological as aging. The aim of this study was to investigate the heart rate (HR) response during a graded exercise test and its recovery in healthy elderly, comparing subjects within serum TSH in the lower limit of reference range to those within the TSH in the upper limit. A cross-sectional study was conducted with 86 healthy elderly aged 71.5 ± 5.1 years, with serum TSH between 0.4 - 4.0 mUl/mL. The participants were divided into two groups according to TSH level: < 1.0 mUl/mL (n = 13) and ≥ 1.0 µUI/mL (n = 73). All participants performed an ergometric test on a treadmill. The HR was recorded and analyzed at rest, during exercise and during the three minutes immediately after exercise. No differences were observed in relation to HR at peak of exercise (TSH < 1.0 µUI/mL: 133.9 ± 22.5 bpm vs. TSH ≥ 1.0 µUI/mL: 132.4 ± 21.3 bpm; p = 0.70) and during the first minute of recovery phase (TSH < 1.0 µUI/mL: 122.3 ± 23.1 bpm vs. TSH ≥ 1.0 µUI/mL: 115.7 ± 18.4 bpm p = 0.33). The groups also presented similar chronotropic index (TSH < 1.0 µUI/mL: 78.1 ± 30.6 vs. TSH ≥ 1.0 µUI/mL: 79.5 ± 26.4; p = 0.74). In this sample studied, there were no difference between lower and upper TSH level concerning HR response during rest, peak of exercise and exercise recovery.

QT Adaptation during Exercise in Cirrhosis

AIM: QT-interval prolongation is frequently seen in cirrhosis; whether it is simply a marker of disease severity is debated. Analysis of QT-interval behavior during physical exercise may disclose more specific abnormalities of cardiac repolarization of cirrhotic cardiomyopathy. MATERIALS AND METHODS: Thirty-eight out-patients with non-alcoholic liver cirrhosis and portal hypertension (32 males, aged 62 ± 9 years) and 36 sex- and age-matched healthy volunteers (32 males; aged 59 ± 7 years) underwent bicycle exercise test with QT-interval measurement, echocardiographic and Doppler analysis of systolic and diastolic left ventricular function, determinations of systemic hemodynamic and pro-brain natriuretic peptide concentration. RESULTS: Patients had longer Fridericia-corrected QT-interval than healthy subjects at baseline and peak-exercise, and reduced chronotropic index, despite similar predicted workload. Corrected-QT shortening extent at peak-exercise was the same; however, in early-exercise, corrected-QT increased in 6 healthy subjects versus 25 patients, and in patients the increase was greater and significantly delayed. QT hysteresis was greater in patients. Abnormal repolarization during exercise and recovery in patients with normal baseline corrected-QT did not correlate to Child-Pugh class and hemodynamic alterations, whereas patients with > 440 ms corrected-QT (n = 16) showed diastolic dysfunction and increased pro-brain natriuretic peptide. CONCLUSIONS: QT behavior during physical exercise supports the hypothesis of anomalous modulation of potassium currents in cirrhosis; only long rest corrected-QT correlates to clinical signs of cirrhotic cardiomyopathy.

Relative Handgrip Strength as a Simple Tool to Evaluate Impaired Heart Rate Recovery and a Low Chronotropic Index in Obese Older Women

Relative Handgrip Strength as a Simple Tool to Evaluate Impaired Heart Rate Recovery and a Low Chronotropic Index in Obese Older Women

Vitamin D3 repletion versus placebo as adjunctive treatment of heart failure patient quality of life and hormonal indices: a randomized, double-blind, placebo-controlled trial

BackgroundVitamin D status may influence heart failure (HF) patient outcomes by affecting b-type natriuretic peptide (BNP), parathyroid hormone (PTH), and enhancing cardiac contractility. Vitamin D deficiency is associated with morbidity and mortality in HF patients. The objective of this study was to determine if vitamin D3 at a comparatively high dose would replete 25-hydroxyvitamin D (25(OH)D) stores, improve BNP, PTH, cardiopulmonary function, reduce inflammatory markers, and improve quality of life (QOL) in HF patients.MethodsThis was a 6 month, parallel group, double-blind, placebo-controlled, single clinic center, randomized trial of supplemental vitamin D3 using a dose of 10,000 IU daily or placebo in 40 vitamin D deficient or insufficient (25(OH)D level ≤ 32 ng/ml) patients with stable New York Heart Association Class II-III HF in a specialty cardiology clinic. All variables were measured at baseline and 6 months. Values between the two treatment groups were assessed using Student’s t-test or Mann-Whitney Test. Univariate analysis of covariance was conducted to adjust for variance in baseline 25(OH)D.ResultsAll results were adjusted for baseline 25(OH)D. The change in BNP from baseline was ∆ +30 ± 950 pg/ml for treatment vs. placebo ∆ +400 ± 1900 pg/ml, p = 0.003. 25(OH)D serum levels rose by 49 ± 32 ng/ml in the treatment group vs 4 ± 10 ng/ml in the placebo group, p < 0.001. PTH and exercise chronotropic response index improved in the treatment group vs placebo group, respectively, but both were attenuated by adjustment ((∆-20 ± 20 pg/ml vs ∆ + 7 ± 53 pg/ml respectively (p = 0.01, adjusted p = 0.07)) and (∆ + 0.13 ± 0.26 vs. ∆-0.03 ± 02.9 respectively, p < 0.01, adjusted p = 0.17)). Other measured cardiopulmonary parameters remained unchanged. High sensitivity C-reactive protein (hsCRP) remained unchanged for women, but improved for men (∆-2 ± 4 treatment versus ∆2 ± 5 mg/L placebo, p = 0.05). QOL scores, including composite overall and clinical summary scores significantly improved in treatment compared to placebo (∆ + 10 ± 15 versus −6 ± 15, p < 0.01 and ∆ + 8 ± 14 versus −8 ± 18, p = 0.01, respectively).ConclusionsRepletion of 25(OH)D may improve QOL in HF patients and may help to normalize BNP, PTH, and hsCRP.Trial registrationClinicaltrials.gov, Trial Registration Number: NCT01636570, First registered 3 July 2012.