Chronotropic Index Research Articles

Chronotropic incompetence predictors in a Cardiac Rehabilitation Program following myocardial infarction

Abstract Background Chronotropic incompetence (CI) has been described in many patients after myocardial infarction (MI) and can negatively affect physical capacity, especially if negative chronotropic therapy (NCT) is prescribed. Prediction of CI after MI could be useful for tailored medical therapy and exercise training prescription. Purpose We aim to predict CI on initial exercise ECG testing (ExECG) in MI patients submitted to a Cardiac Rehabilitation Program (CRP). Methods Patients with ST-segment elevation MI (STEMI) or occlusion MI (OMI) submitted to our CRP were prospectively included. After an initial follow-up phase of clinical stabilization and medical therapy optimization, ExECG (conventional or cardiopulmonary) was performed. Peak VO2 and chronotropic reserve index [(maximum heart rate – resting heart rate) / ([220-age] – resting heart rate)] were measured. Chronotropic incompetence was defined as <80% chronotropic reserve index (≤62% in patients treated with NCT). Pharmacological therapy with NCT was registered in absolute and equivalent doses per bisoprolol 2.5mg units (B2.5EU). The effect of NCT on CI was studied by ANOVA test, and predictors of CI by binary logistic regression analysis. The model was tested by area under the curve (AUC) analysis in receiver operating characteristic curves. A p<0.05 was considered statistically significant. Results The cohort comprised 143 patients, mostly middle-aged (mean 60.3±15.8 years) males (85.3%) with anterior or inferior MI (44.8% and 44.8%, respectively). Mean left ventricular ejection fraction (LVEF) was 52.4±10.6% and 36.4% depicted LVEF<50%. NCT was prescribed in most patients (n=125, 87.4%), and median equivalent dose was 1 [0.5-1] B2.5EU. CI was noted on more than half of the population on initial ExECG (n=75, 52.4%). Higher NCT doses per B2.5EU associated with worse mean chronotropic reserve indexes: 72.8±24.4% in patients without NCT; 71.7±18.7% in patients with 0.5 B2.5EU; 62.8±18.2% in patients with 1 B2.5EU; and 58.7±16.9% in patients with ≥2 B2.5EU (ANOVA p=0.04). On binary logistic regression analysis, only two variables were independent predictors of CI: diabetes mellitus (HR 3.02 [1.26-7.23], p=0.01) and LVEF (0.97 [0.94-0.99] per increased %, p=0.04). However, the predictive power of the model was poor (AUC 0.62 [0.53-0.71], p=0.01). Conclusions Chronotropic incompetence after a MI is associated with lower LVEF, diabetes mellitus, and higher doses of NCT. Although significant interindividual variability exists in chronotropic response in the post-infarction period, these factors could be taken into consideration for tailored prescription (or deprescription), especially in patients who may not derive any prognostic benefit from NCT.Chronotropic incompetence in CRP

The Role of Electrocardiographic Exercise Testing for the Possibility of Permanent Pacemaker Implantation in Patients with Sinus Bradycardia.

Study on the role of electrocardiographic (ECG) exercise testing for the possibility of permanent pacemaker implantation (PPI) in patients with sinus bradycardia (SB). Cross-sectional descriptive, prospective study. The study on 60 patients with SB below 50 beats/minute on 12-lead electrocardiogram at rest, with or without symptoms of SB, conducted at the Vietnam National Heart Institute and Hanoi Heart Hospital from January 2020 to September 2021. Sixty patients with SB were studied, 36 male (60%) and 24 female patients (40%), p > 0.05. The average age was 55.12 ± 13.89 years old. Maximum exercise capacity (MEC) is low and only reaches 7.78 ± 3.59 metabolic equivalents (METs); Not reaching 85% of predicted MEC accounts for 53.5%; Maximum exercise time is 10.53 ± 0.46 minutes; Impaired heart rate (HR) variability in patients with SB is high: Chronotropic Index <0.8 accounts for 53.5%, not reaching 85% of predicted HR max accounts for 45%. The average HR max was 129.90 ± 29.22 beats per minute (BPM). The average maximum workload systolic blood pressure was 155.23 ± 20.59 mmHg. The average value of maximum exercise diastolic blood pressure was 88.10 ± 9.11 mmHg. The HR decreased by 27.87 ± 16.82 BPM in the first minute. Not achieving 85% of predicted MEC (p = 0.062), so it is not an independent factor predicting the ability for PPI. Only the HR variability index <0.8 is an independent predictor for PPI in bradycardic patients, which has OR = 21.521 (95% CI: 2.27-04.34, p < 0.05). Results can be seen that Chronotropic Index <0.8 is an important marker for physicians to decide on PPI in ECG during exercise testing in SB patients and is a potential prognostic factor for the need for PPI.

Chronotropic index, heart rate and exercise capacity in diabetes mellitus: comparing two different high-intensity interval training protocols

Chronotropic index, heart rate and exercise capacity in diabetes mellitus: comparing two different high-intensity interval training protocols

Impact of Chronotropic Incompetence and Correlation with Exercise Tolerance in Patients with Implantable Cardiac Devices Undergoing a Phase II Cardiac Rehabilitation Program Article Sidebar

Objective: Since patients with implantable cardiac devices tend to develop chronotropic incompetence (CI) associated with the effect of the device itself or the pharmacological effect of the underlying disease, CI could act as a limiting factor in improving exercise tolerance in patients undergoing cardiac rehabilitation program, since an increase in HR is a crucial part in improving cardiac output as a central component of oxygen consumption (VO2). However, it has been observed that there could be other factors contributing to the improvement in exercise tolerance in these patients regardless of the presence of CI. The aim of this research is to clarify the effect of chronotropic incompetence on the improvement in exercise capacity in patients with implantable cardiac devices after a phase II cardiac rehabilitation program (CRP). Methods: Quasi-experimental study applied to patients with implantable cardiac devices (ICDs, CRT, pacemakers) undergoing a supervised concurrent CRP, lasting 4-6 weeks, at an intensity between 65-80% of heart rate reserve (HRR), associated with kinesiotherapy sessions (with strength and endurance training and other biomotor qualities) and interdisciplinary intervention, education, and counseling. CI was calculated using the chronotropic response index, and METs-load measurement was performed at the beginning and at the end of the intervention. Results: Forty patients with a mean age of 61.4 years were included, mostly male (29) 72.5%, (23) 57.5% diagnosed with heart failure, and regarding the type of device, pacemakers (20) 50%, implantable cardioverter-defibrillator (ICD) (12) 30%, and cardiac resynchronization therapy with defibrillator (CRT-D) (20) 8%, of the total patients (35) 87.5% presented chronotropic incompetence and only (5) 12.5% with normal chronotropic response at the end of the intervention. A significant decrease in the chronotropic response index from 0.70 to 0.47 (p &lt;0.001) and a significant increase in METs-load from 5.47 to 9.35 (p &lt;0.001) were found. The value of the differential between initial and final METs (delta-METs) was obtained for both groups, observing a significant increase between initial and final METs in favor of patients with CI (3.8 Vs 3.5, p&lt;0.012) at the end of the intervention. A significant moderate negative correlation (r=-0.395, Spearman, p&lt;0.012) was determined between the degree of CI and final METs-load. Conclusions: It was observed that patients with implantable cardiac devices undergoing a CRP show an increase in exercise tolerance measured in METs, with an inversely proportional correlation to chronotropic incompetence.

Chronotropic incompetence is associated with reduced aerobic conditioning and sedentary behavior in patients with post-acute COVID-19 syndrome.

Post-acute COVID-19 syndrome, or long COVID, presents with persistent symptoms, including cough, dyspnea, and fatigue, extending beyond one month after SARS-CoV-2 infection. Cardiac complications such as chest pain and arrhythmias have raised concerns, with chronotropic incompetence (CI), an inadequate heart rate increase during exercise, emerging as a significant condition contributing to diminished exercise tolerance and quality of life. This study estimated the prevalence of CI and explored its association with aerobic capacity and physical activity levels in long COVID patients. A cross-sectional study was conducted at a private hospital in Sergipe, Brazil, involving 93 patients over 18 years old with persistent post-COVID-19 symptoms after confirmed SARS-CoV-2 infections. Exclusion criteria included beta-blocker use, inadequate respiratory exchange ratio, and inability to complete cardiopulmonary exercise testing (CPET). Clinical histories, CPET results, and chronotropic index calculation were used to identify CI, with logistic regression analyzing associated factors. Of the participants (mean age 45 years; average duration since COVID-19 diagnosis 120 days), 20.4% were diagnosed with CI. Logistic regression identified a strong association between CI and sedentary behavior (OR 11.80; 95% CI 2.54 to 54.78; p=0.001). Patients with CI showed lower predicted peak heart rates and maximal oxygen uptake. The prevalence of CI among long COVID patients in this study was approximately 20%, associated with decreased aerobic capacity and increased sedentary behavior. These findings highlight the need for timely diagnosis and therapeutic interventions, including cardiopulmonary rehabilitation, to enhance the quality of life in post-COVID patients with CI. The study's cross-sectional design and its specific context have limited causality inference and generalizability, underscoring the importance of further research in diverse settings.

Prognostic significance and pathophysiological insights of functional phenotypes clustering

Abstract Background Functional capacity (FC) is a marker of cardiorespiratory fitness reflecting the integrity of cardiac, respiratory and peripheral metabolic systems. Cardiopulmonary exercise test (CPET) is the method of reference to quantify the functional capacity through a multiparametric approach. Functional phenotypes can be identified according with the patterns of CPET variables. We sought to explore the prognostic role of CPET-derived functional phenotypes, identified by an automatic clustering process, and to understand the underlying cardiac pathophysiology as assessed by exercise-echocardiography (Exe-Echo). Methodology 1379 unselected subjects who underwent to CPET combined with Exe-Echo were included in the study. Cluster analysis based on CPET variables (% of predicted peakVO2, anaerobic threshold, VE/VCO2, peak respiratory ratio, chronotropic index, O2 pulse, peak PetCO2, VO2/WR slope and heart rate recovery) identified 4 clusters (C1= 207, C2= 546, C3= 475, C4= 151 subjects), differing primarily for a progressive worsening of FC (% of PeakVO2: 87±18, 75±13, 60±14, 48±13%; VE/VCO2 25.3±2.7, 26.5±3.0, 30.8±4.3, 39.4±7.8; in C1, C2, C3, C4 respectively, all p&amp;lt;.001). Rest and exercise parameters of Exe-Echo were used to define cardiac characteristics and presented in a standardized radar clustering (fig 1). Patients were tracked for the combined end-point of death + heart failure hospitalization. Results C1 presented normal cardiac morphology and function with expected increase of stroke volume (SV) and cardiac output (CO) during exercise, without significant valvular disease; C2 and C3 showed a mild-to-medarately abnormal rest and exercise echo parameters, characterized by LV progressive dilatation, mild systolic dysfunction, mitral regurgitation (MR) and increased systolic pulmonary pressure (SPAP); C4 corresponded to severe cardiac remodelling with LV and left atrial enlargement, severe MR, rest pulmonary hypertension and severely impaired contractile reserve (reduced exercise SV and CO). The 4 clusters were strongly associated with prognosis, as shown by KM of survival free from combined event (p&amp;lt;.0001; fig 2). Conclusions automatic clustering of CPET parameters identified 4 clusters strongly associated with hard end-points (mortality and HF hospitalization). Exe-Echo provided cluster-related pathophysiological insights explaining the mechanisms responsible for prognosis decline. This combined CPET-ExeEcho approach may help in identifying high risk patients and in defining new therapeutic targets.Radar chart of echo variablesKM of combined end-point (death+HF)

Exercise capacity of the patients after cardiac surgery with special reference to left atrium incision

Abstract Background Chronotropic incompetence (CI) is sometimes observed during exercise in patients who underwent cardiac surgery, however, little is known which factors affect to the incidence of CI and exercise capacity of those patients. Purpose We hypothesized that the incidence of CI is higher in patients with left atrium incision (LAI) as compared with those without LAI, which is caused by impairment of cardiac sympathetic nerves by LAI. The purpose of this study is to elucidate whether LAI causes CI, and if so, to analyze which factor determine the exercise capacity of the patients with LAI. Methods We performed cardiopulmonary exercise testing in total 157 patients who had undergone elective cardiac operation (46 patients with LAI, 111 patients without LAI). We analyzed chronotropic response index (CRI), parameters of exercise capacity, echocardiography, and blood hemoglobin concentration (Hb). Results The value of CRI was significantly reduced in the patients with LAI as compared with those without LAI (0.24±0.22 vs. 0.45±0.17, respectively, p&amp;lt;0.001). Exercise capacity such as peak oxygen uptake (peak VO2), anaerobic threshold showed no significant difference between two groups. In patients with LAI, peak VO2 showed significant correlations between peak oxygen pulse (peak VO2/HR; r=0.34, p&amp;lt;0.05), Hb (r=0.43, p&amp;lt;0.005) and left atrium dimension (LAD) measured by echocardiography (r=-0.56, p&amp;lt;0.001). Conclusions The present study demonstrated that higher incidence of CI was observed in patients with LAI as compared with those without LAI. Moreover, peak VO2 of patients with LAI showed significant correlations with peak VO2/HR, Hb and LAD. These results suggest that 1) LAI may impairs cardiac sympathetic nerves and causes CI, 2) peak VO2/HR and its component Hb are important factors which determine exercise capacity of patients with CI, 3) LAD which indicates left atrial function may also affect exercise capacity of patients with CI.

Abstract 16944: Risk Stratification With Hemodynamic Gain Index and Peak Rate-Pressure Product in Patients With Chronic Heart Failure Undergoing Treadmill Exercise Testing

Introduction: We recently demonstrated the combined prognostic value of two simple non-invasive parameters obtained from treadmill exercise testing in patients with HFrEF, the hemodynamic gain index (HGI) and peak rate-pressure product (pRPP). However, their prognostic value is yet to be validated in patients with undifferentiated HF syndrome. Hypothesis: Both HGI and pRPP predict all-cause mortality in patients with chronic HF. Methods: We identified 126,356 consecutive patients undergoing treadmill exercise testing for HF symptom evaluation between 1/1991-2/2015. Patients with a confirmed diagnosis of HF were included. HGI was calculated from [(SBPpeak x HRpeak) - (SBPrest x HRrest)]/(SBPrest x HRrest), and pRPP was calculated from SBPpeak x HRpeak. Hazard ratios per doubling of HGI and pRPP for all-cause mortality were estimated using multivariable Cox regression models with adjustment for traditional cardiovascular risk factors and exercise testing parameters (chronotropic reserve index, METs, abnormal heart rate recovery, and total exercise time). Optimal cut-off for HGI and pRPP were determined by the Youden’s index. Kaplan-Meier plots with log-rank test across patients with low or high HGI and pRPP were used. Results: There were 5,940 patients with symptomatic HF diagnosis included in the analysis (mean age 56.2±12.4 years, 68.1% male, 46.5% with CAD, 55.8% with beta-blocker use). During the median follow up of 7.1 years, 2,222 (37.4%) patients died. Higher both HGI and pRPP were associated with a lower risk of mortality (hazard ratio 0.85 [0.81-0.90] and 0.72 [0.62-0.84], respectively, all P &lt;0.001). Optimal cut-off values for HGI and peak RPP were 1.06 and 18,966, respectively. Figure 1 shows Kaplan-Meier plots across patients with low and high HGI and pRPP (log-rank P &lt;0.001). Conclusions: Both HGI and pRPP are predictors of mortality in patients with chronic HF and can be used for prognostication and referral for advanced HF therapy evaluation.

Effects of smoking on the cardiopulmonary modulation during physical exercise in middle-aged non-obese healthy individuals

Objective:&#x0D; The aim of this study was to evaluate the overall effects of smoking and its duration on various cardiopulmonary modulation mechanisms during physical exercise in middle-aged non-obese healthy individuals.&#x0D; Materials and Methods:&#x0D; Two hundred forty-three (142 smokers and 101 non-smokers), middle-aged, non-obese, healthy individuals were evaluated in this cross-sectional study. Parameters of pulmonary function including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1) and FEV1/FVC ratio were evaluated using a spirometer and systolic pulmonary artery pressure (sPAP) were measured by echocardiography on rest and during various levels of exercise. A treadmill exercise test was used to assess heart rate recovery index (HRRI), the chronotropic index (CI) and the maximum rate of oxygen consumption during exercise (VO2max). &#x0D; Results:&#x0D; Resting sPAP values were higher and FEV1, FVC and FEV1/FVC values were lower among smokers. As compared to resting values; FEV1 and FEV1/FVC ratio in smokers decreased significantly at peak exercise level (2.66±0.54 vs 2.35±0.49, p

Comparison of serum N-terminal pro-brain natriuretic peptide levels, conventional echocardiography, exercise parameters, and dyssynchrony measurements in Fontan patients.

Little data are available concerning the methods used in the long-term follow-up of Fontan patients. We analyzed the association between serum N-terminal pro-brain natriuretic peptide levels, conventional echocardiography findings, exercise parameters, and dyssynchrony measurements in patients who underwent Fontan surgery. This study included 28 patients who underwent Fontan surgery (mean age 12.8 ± 4.36 years) and 27 healthy controls (mean age 12.5 ± 3.76 years). Echocardiography examinations and exercise tests were performed in both groups. The systemic ventricle was examined via echocardiography, dyssynchrony measurement was performed, the systemic ventricular myocardial performance index was calculated, and serum N-terminal pro-brain natriuretic peptide levels were measured for all subjects. Lower cardiac output, stroke volume, maximal work, chronotropic index, maximal oxygen uptake, and higher N-terminal pro-brain natriuretic peptide levels were observed in the Fontan group than in the control group (p < 0.05). A negative correlation was found between physical exercise parameters and N-terminal pro-brain natriuretic peptide levels and dyssynchrony measurements. Measurements of exercise capacity, serum N-terminal pro-brain natriuretic peptide levels, and dyssynchrony measurement were more valuable than conventional methods for assessing patients' clinical and functional status. Dyssynchrony measurements provided better information about ventricular status than did conventional echocardiography studies. While patients' systolic function determined by conventional echocardiography was normal, dyssynchrony measurements showed the opposite result. The negative relationship between serum N-terminal pro-brain natriuretic peptide levels, dyssynchrony measurements, and exercise capacity suggests that these parameters should be investigated further in Fontan patients.

Exercise Test Predicts Both Noncardiovascular and Cardiovascular Death in a Primary Prevention Population

ObjectiveTo identify specific causes of death and determine the prevalence of noncardiovascular (non-CV) deaths in an exercise test referral population while testing whether exercise test parameters predict non-CV as well as CV deaths. Patients and MethodsNon-imaging exercise tests on patients 30 to 79 years of age from September 1993 to December 2010 were reviewed. Patients with baseline CV diseases and non-Minnesota residents were excluded. Mortality through January 2016 was obtained through Mayo Clinic Records and the Minnesota Death Index. Exercise test abnormalities included low functional aerobic capacity (ie, less than 80%), heart rate recovery (ie, less than 13 beats/min), low chronotropic index (ie, less than 0.8), and abnormal exercise electrocardiogram (ECG) of greater than or equal to 1.0 mm ST depression or elevation. We also combined these four abnormalities into a composite exercise test score (EX_SCORE). Statistical analyses consisted of Cox regression adjusted for age, sex, diabetes, hypertension, obesity, current and past smoking, and heart rate–lowering drug. ResultsThe study identified 13,382 patients (females: n=4736, 35.4%, 50.5±10.5 years of age). During 12.7±5.0 years of follow-up, there were 849 deaths (6.3%); of these 162 (19.1%) were from CV; 687 (80.9%) were non-CV. Hazard ratios for non-CV death were significant for low functional aerobic capacity (HR, 1.42; 95% CI, 1.19 to 1.69; P<.0001), abnormal heart rate recovery (HR, 1.36; 95% CI, 1.15 to 1.61; P<.0033), and low chronotropic index (HR, 1.49; 95% CI, 1.26 to 1.77; P<.0001), whereas abnormal exercise ECG was not significant. All exercise test abnormalities including EX_SCORE were more strongly associated with CV death versus non-CV death except abnormal exercise ECG. ConclusionNon-CV deaths predominated in this primary prevention cohort. Exercise test abnormalities not only predicted CV death but also non-CV death.

Effects of childhood obesity on myocardial performance, autonomic and conduction properties of the heart.

Childhood obesity tends to persist into adulthood and associated with increase in developing ischemic and non-ischemic cardiovascular diseases. We aimed to evaluate the effect of obesity on cardiac functions, atrial electromechanical coupling, and heart rate response, which are considered to be predictors of atrial fibrillation and sudden cardiac arrest. Study population included 52 obese children and 52 healthy controls. We performed 12-lead electrocardiography, echocardiographic examination, and treadmill exercise testing. Mitral, septal, and tricuspid segments were analysed by tissue Doppler imaging. Myocardial performance index (p = 0.011, p < 0.001, and p = 0.001, respectively) was higher and E'/A' ratio (p = 0.011, p < 0.001, and p < 0.001, respectively) was lower in obese group than controls. Atrial electromechanical coupling was longer in the obese group at all three segments (p < 0.001, p = 0.009, and p = 0.04, respectively). They had significantly longer interatrial (p < 0.001) and intra-atrial (p = 0.003) electromechanical conduction delay. While chronotropic index was similar between two groups, heart rate reserve was lower in obese children than controls (p = 0.043). The 1st- and 2nd-minute heart rate recovery indices of the obese group were lower compared to controls (p < 0.001 and p = 0.03, respectively). Body mass index was positively correlated with intra- and inter-atrial conduction times, whereas it was negatively correlated with heart rate recovery indices. We showed a deterioration in the diastolic function, atrial conduction, and heart rate response properties in children with obesity. Given the prognostic importance of these parameters, obese patients are might be at risk for atrial fibrillation and severe dysrhythmias from a young age.

Chronotropism in CPET - Is incompetence limiting functional capacity?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Chronotropic incompetence (CI) is defined as the inability to reach 80% of the expected reserve frequency for age during exertion, and it is frequently observed in stress tests of patients undergoing cardiac rehabilitation programs due to a combination of factors, that include the use of betablockers. Despite the theoretical basis for suggesting that a lower peak heart rate is related to a lower tolerance to exertion, we lack data correlating the CI to the maximal functional capacity, measured in cardiopulmonary tests as the maximal oxygen volume consumption (peak VO2). Purpose To correlate the impact of CI on functional capacity in patients (pts) undergoing a cardiac rehabilitation program and try to find the best value of chronotropic incompetence that could predict a worse prognosis. Methods Prospective cohort study which included consecutive pts who were submitted to cardiopulmonary exercise test (CPET) during 5 years in a tertiary hospital. Demographic data were analyzed and medication with beta blocker was registered. CI and chronotropic index were calculated using the equation (220-age) for estimating maximum HR. ROC curve method and Kaplan-Meier survival analysis were used to evaluate the cut-off efficacy. Results We analyzed 358 CPET and 74,1% patients (n=206) were under beta blocker therapy (7,6% high dose). The majority of the patients had CI (83.5%); CI was more frequent in pts under BB therapy although it didn’t reach statistical significance (p=0.12). A low maximum predicted heart rate (mpHR) was associated with low peak VO2 (p=0.02) and a mpHR &amp;lt; 61% was the best value to predict peak VO2&amp;lt; 12mL/(kg.min) (AUC=0.746, S=72; E=65), despite not showing association with cardiovascular events. Regarding the chronotropism, 96.9% of the pts were categorized as having a low chronotropic index . A CI &amp;lt; 0.38 was the best cut-off to predict a peak VO2&amp;lt;12 mL/(kg.min) (AUC=0.81, S=72, E 76) and it was predictor of all-cause hospitalizations (p=0.015). Conclusion This study shows a high percentage of pts with CI. A low cronotropic index was associatated with low peak VO2 and was a predictor of all-cause hospitalizations.

Chronotropic incompetence and exercise capacity after cardiac surgery with left atrium incision

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Chronotropic incompetence (CI) is sometimes observed during exercise training of cardiac rehabilitation in patients who underwent cardiac surgery, however, little is known which factors affect to the incidence of CI and exercise capacity of those patients. Purpose Because the possibility exists that cardiac sympathetic nerves might be impaired by surgical procedure, moreover CI is sometimes observed in patients after mitral valve surgery, we hypothesized that the incidence of CI was higher in patients with left atrium incision (LAI) during surgical operation as compared with those without LAI. And if so, which factor determines the exercise capacity of patients after cardiac surgery with LAI. We thus aimed this study to elucidate the hypothesis with cardiopulmonary exercise testing (CPX). Methods We performed CPX in total 153 patients who had undergone elective cardiac operation (45 patients with LAI, age 60.5±11.0; 108 patients without LAI, age 62.0±11.7). We analyzed chronotropic response index (CRI), peak oxygen uptake (peak VO2/W), anaerobic threshold (AT), and peak oxygen pulse (peak VO2/HR) with CPX, echocardiography, and blood hemoglobin concentration (Hb). Results The value of CRI was significantly reduced in the patients with LAI as compared with those without LAI (with LAI 0.24±0.22 vs. without LAI; 0.44±0.18, p&amp;lt;0.001). Exercise capacity such as peak oxygen uptake (peak VO2), anaerobic threshold showed no significant difference between two groups. In patients with LAI, peak VO2 showed significant correlations between peak oxygen pulse (peak VO2/HR; r=0.36, p&amp;lt;0.05), Hb (r=0.40, p&amp;lt;0.01) and left atrium dimension (LAD) measured by echocardiography (r=-0.54, p&amp;lt;0.001). Conclusions The present study demonstrated that higher incidence of CI was shown in patients with LAI as compared with those without LAI. Moreover peak VO2 of patients with LAI showed significant correlations with peak VO2/HR, Hb and LAD. These results suggest that 1) left atrium incision impairs cardiac sympathetic nerves and causes CI, 2) peak VO2/HR and Hb which is essential element of oxygen pulse are important factors for exercise capacity in patients after LAI with CI. Left atrium enlargement may indicates pre-operative damages of left atrium, 3) LAD which may indicate left atrium function, also is an important factor of exercise capacity in those patients.

12-week Brisk Walking Improved Chronotropic Response in Hypertensive Patients.

We investigated the effects of 12-week brisk walking on chronotropic response in hypertensive patients aged 40-69. 77 participants in exercise group underwent 12-week brisk walking, while 66 participants in control group received health education. Chronotropic parameters, resting blood pressure, and physical fitness including peak oxygen consumption (VO2peak) were measured. After 12 weeks, the systolic blood pressure (SBP) was decreased (-6.104 mmHg, 95%CI -8.913 to -3.295 mmHg, P<0.0001), while metabolic chronotropic relationship (MCR) slope and VO2peak were increased (0.073, 95%CI 0.001 to 0.145, P=0.046; 1.756 mL/kg/min, 95%CI 0.891 to 2.622 mL/kg/min, P<0.0001) in exercise group compared to baseline. The chronotropic response index (CRI) at 25-75 W load were decreased (-0.210, 95%CI -0.307 to -0.112, P<0.0001; -0.144, 95%CI - 0.204 to -0.083, P<0.0001; -0.078, 95%CI -0.135 to -0.022, P=0.007) in control group after 12 weeks. The relative changes (%Δ) of systolic and diastolic blood pressure were negatively correlated with %ΔVO2peak (r=-0.233, r=-0.187), while %ΔMCR and %ΔCRI at 50-75 W load were positively correlated with %ΔVO2peak after 12 weeks (r=0.330, r=0.282, r =0.370). %ΔSBP was also positively correlated with %ΔMCR (r =-0.213). In conclusion, 12-week brisk walking reduced SBP by improving chronotropic response in hypertensive patients aged 40-69. The enhanced chronotropic response was associated with enhanced cardiorespiratory fitness.

Development and Initial Validation of a Frailty Score for Pediatric Patients with Congenital and Acquired Heart Disease.

Frailty is a multi-dimensional clinical syndrome that is associated with increased morbidity and mortality and decreased quality of life. Children/adolescents with heart disease (HD) perform significantly worse for each frailty domain compared to non-HD peers. Our study aimed to create a composite frailty score (CFS) that can be applied to children/adolescents with HD and evaluate associations between the CFS and outcomes. Children and adolescents (n = 30) with HD (73% single ventricle, 20% heart failure, 7% pulmonary hypertension) were recruited from 2016 to 2017 (baseline). Five frailty domains were assessed at baseline using measures validated for pediatrics: (1) Slowness: 6-min walk test; (2) Weakness: handgrip strength; (3) Fatigue: PedsQL Multi-dimensional Fatigue Scale; (4) Body composition: triceps skinfold thickness; and (5) Physical activity questionnaire. Frailty points per domain (range = 0-5) were assigned based on z-scores or raw questionnaire scores and summed to produce a CFS (0 = least frail; 25 = most frail). Nonparametric bootstrapping was used to identify correlations between CFS and cross-sectional change in outcomes over 2.2 ± 0.2years. The mean CFS was 12.5 ± 3.5. In cross-sectional analyses of baseline data, correlations (|r|≥ 0.30) were observed between CFS and NYHA class, the number of ancillary specialists, total prescribed medications, heart failure medications/day, exercise test derived chronotropic index and percent predicted VO2peak, and between child and parent proxy PEDsQL. At follow-up, CFS was correlated with an increase in the number of heart failure medications (r = 0.31). CFS was associated with cross-sectional outcomes in youth with heart disease. Longitudinal analyses were limited by small sample sizes due to loss to follow-up.

Abstract 13469: A Risk Score Model to Identify Patients With High Likelihood of Left Main or 3-vessel Coronary Artery Disease

Introduction: Revascularization improves outcomes only for stable coronary artery disease (CAD) patients with high-risk coronary anatomy (HRCA). While exercise stress test (EST) is the screening modality for CAD, identifying HRCA noninvasively is challenging. We aimed to derive a prediction model, incorporating clinical and EST characteristics, to screen for HRCA. Methods: We included adult patients who underwent EST followed by elective invasive coronary angiography (ICA) at our center between 2017 and 2019. HRCA was defined as left main (LM) or 3-vessel disease on ICA. Significant CAD was defined as ≥50% stenosis in the LM and/or ≥70% stenosis in the 3 main vessels. We excluded patients with acute coronary syndrome or ejection fraction &lt;50%. Variables with p&lt;0.1 at univariable analysis were selected as candidates to enter a multivariable stepwise backward regression model to derive a HRCA risk model. Results: 304 consecutive patients met inclusion criteria (64[13]years, 81.6% M). 15.5% were found to have HRCA on ICA. Median time from EST to ICA was 11[31]days. The following hit the threshold for inclusion into the multivariable model: hypertension, maximal predicted heart rate (MPHR), diabetes, rate pressure product, metabolic equivalents, exercise time, chronotropic response index ≥0.8, heart rate recovery, Duke Treadmill Score (DTS). After backward selection, hypertension (OR 17.08, p=0.008), MPHR (0.98, p=0.048), and very abnormal DTS (8.26, p=0.001) were the only significant predictors of HRCA ( Fig.1A ). The fully adjusted model showed good discrimination for HRCA (AUC 0.74, p&lt;0.001, Fig.1B ). Conclusions: In an era of declining emphasis on EST in favor of imaging stress test, we identified a risk model based on clinical and EST-derived parameters, that can accurately predict likelihood of HRCA, enabling personalized risk-stratification. Further studies are needed to externally validate our model.

Índice cronotrópico y eventos adversos a largo plazo en insuficiencia cardiaca con fracción de eyección conservada

Introduction and objectivesLittle is known about the usefulness of heart rate (HR) response to exercise for risk stratification in heart failure with preserved ejection fraction (HFpEF). Therefore, this study aimed to assess the association between HR response to exercise and the risk of total episodes of worsening heart failure (WHF) in symptomatic stable patients with HFpEF. MethodsThis single-center study included 133 patients with HFpEF (NYHA II-III) who performed maximal cardiopulmonary exercise testing. HR response to exercise was evaluated using the chronotropic index (CIx) formula. A negative binomial regression method was used. ResultsThe mean age of the sample was 73.2± 10.5 years; 56.4% were female, and 51.1% were in atrial fibrillation. The median for CIx was 0.4 [0.3-0.55]. At a median follow-up of 2.4 [1.6-5.3] years, a total of 146 WHF events in 58 patients and 41 (30.8%) deaths were registered. In the whole sample, CIx was not associated with adverse outcomes (death, P=.319, and WHF events, P=.573). However, we found a differential effect across electrocardiographic rhythms for WHF events (P for interaction=.002). CIx was inversely and linearly associated with the risk of WHF events in patients with sinus rhythm and was positively and linearly associated with those with atrial fibrillation. ConclusionsIn patients with HFpEF, CIx was differentially associated with the risk of total WHF events across rhythm status. Lower CIx emerged as a risk factor for predicting higher risk in patients with sinus rhythm. In contrast, higher CIx identified a higher risk in those with atrial fibrillation.

Low chronotropic index predicts rehospitalization in post-acute myocardial infarction patients with preserved or mildly reduced left ventricular ejection fraction

Abstract Background There are limited data about the clinical utility of combined stress echocardiography and cardiopulmonary exercise testing (CPET-ESE) in predicting prognosis in patients after acute myocardial infarction (AMI) with preserved left ventricular ejection fraction (LVEF). Aim To assess prognostic parameters using CPET-ESE in post-AMI patients with preserved or mildly reduced LVEF. Methods Eighty-seven patients after the first AMI with LVEF &amp;gt;40% were followed for 2 years (median 1.93 years IQR 1.16–2.41). The composite end-point was all-cause mortality or rehospitalization due to ischaemic heart disease (AMI, unstable angina, percutaneous coronary intervention/coronary artery bypass grafting) or heart failure exacerbation. All patients underwent symptom-limited CPET-ESE on a semi-supine cycle ergometer 3 to 5 weeks after AMI. The chronotropic index was calculated as the percent of heart rate reserve. Six patients refused to complete the survey and they were not included in the analysis. Results Follow-up was conducted in 81 consecutive patients (mean age 59±10 years, 62% males, 50% AMI with ST-segment elevation, 85% on beta-blockers). Mean LVEF was 56±9% and peak VO2 18.5±5.0 mL/kg/min. There were no deaths during follow-up. The composite end-point occurred in 13 patients. In multivariate Cox regression analysis after correction for demographic and clinical variables, only chronotropic index correlated with the composite end-point (HR 0.93, 95% CI 0.87–0.99, p=0.026). A positive predictive value of 33.3% and a negative predictive value of 91.3% (sensitivity 61.5%, specificity 76.5%, area under the curve, AUC 71%) for predicting the composite end-point was established for the chronotropic index ≤36.8% (Fig. 1). There was a statistically significant difference in the composite end-point occurrence (p&amp;lt;0.01) between subgroups with the chronotropic index above and below that threshold (Fig. 2). Conclusions In patients after the first AMI with preserved or mildly reduced left ventricular systolic function, a lower chronotropic index is a predictor of rehospitalization in 2-year follow-up. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Centre of Postgraduate Medical Education, Warsaw, Poland

12-week Moderate-intensity Brisk Walking Improved Chronotropic Response In 40- To 69-year-old Patients With Hypertension

PURPOSE: The aim of this study was to investigate the effect of 12-week brisk walking on chronotropic response in 40- to 69-year-old hypertensive patients in order to provide a scientific theory for improving the prognosis of hypertension with exercise. METHODS: In this study, we included 68 hypertensive patients aged 40-69 in Beijing and Hebei Province in 12-week brisk walking intervention, and 34 hypertensive patients age- and gender-matched as control group. The patients included were free of beta blocker therapy. Participants in exercise group underwent 12-week brisk walking 3 times a week, with the intensity gradually increased from 40-49% to 50-59% heart rate reserve, and the duration gradually increased from 30 to 60 minutes each time. Resting blood pressure, resting heart rate and peak oxygen consumption (VO2peak) were measured. Chronotropic parameters were calculated according to the formula, including metabolic chronotropic relationship (MCR), chronotropic response index (CRI) at all stages. %Δ means the percentage of the difference of indicators between before and after intervention. RESULTS: (1) The systolic blood pressure of hypertensive patients was decreased after intervention of 12-week brisk walking (135.60 ± 13.08 vs 128.52 ± 12.62 mmHg, p < 0.0001) compared to the control group. (2) The %ΔMCR was increased in exercise group after intervention compared to the control group. ((-0.94 ± 25.20) vs (7.14 ± 27.11) %, p = 0.013). (3) The CRI at 50 W- and 75 W-load, CRI2 and CRI3, were decreased after 12 weeks in control group (CRI2: 0.87 ± 0.22 vs 0.77 ± 0.20, p = 0.033; CRI3: 0.96 ± 0.12 vs 0.89 ± 0.10, p = 0.022), while no statistical difference was seen in the exercise group. (4) VO2peak was increased in exercise group after intervention compared to the control group (29.23 ± 4.84 vs 30.52 ± 5.21 mL/kg/min, p = 0.008). (5) The %ΔVO2peak was positively correlated with the %ΔMCR in exercise group (r = 0.269, p = 0.027). CONCLUSIONS: The 12-week moderate-intensity brisk walking significantly reduced systolic blood pressure and improved chronotropic response in 40- to 69-year-old hypertensive patients. Furthermore, the improvement of chronotropic response was associated with increased cardiopulmonary fitness. Supported by National Key Research and Development Program in China (NO. 2016YFC1300202).