Presence Of Chronotropic Incompetence Research Articles

The effect of chronotropic incompetence on physiologic responses during progressive exercise in people with Parkinson's disease.

Heart rate (HR) response is likely to vary in people with Parkinson's disease (PD), particularly for those with chronotropic incompetence (CI). This study explores the impact of CI on HR and metabolic responses during cardiopulmonary exercise test (CPET) in people with PD, and its implications for exercise intensity prescription. Twenty-eight participants with mild PD and seventeen healthy controls underwent CPET to identify the presence or absence of CI. HR and metabolic responses were measured at submaximal (first (VT1) and second (VT2) ventilatory thresholds), and at peak exercise. Main outcome measures were HR, oxygen consumption (VO2), and changes in HR responses (HR/WR slope) to an increase in exercise demand. CI was present in 13 (46%) PD participants (PDCI), who during CPET, exhibited blunted HR responses compared to controls and PD non-CI beyond 60% of maximal workload (p ≤ 0.05). PDCI presented a significantly lower HR at VT2, and peak exercise compared to PD non-CI and controls (p ≤ 0.001). VO2 was significantly lower in PDCI than PD non-CI and controls at VT2 (p = 0.003 and p = 0.036, respectively) and at peak exercise (p = 0.001 and p = 0.023, respectively). Although poorly understood, the presence of CI in PD and its effect on HR and metabolic responses during incremental exercise is significant and important to consider when programming aerobic exercises.

Exercise performance and the risk of incident atrial fibrillation

Abstract Background Atrial fibrillation (AF) is a global health problem that correlates with the increased risks of cardiovascular diseases, quality of life, mortality and global health expenditures. While many of cardiovascular risk factors have been related to the development of AF, a satisfied lifestyle behavior, including regular exercise and a good cardiorespiratory fitness, could be the upstream intervention to modify the risk factors and reduce the AF incidence. Purpose We examined the relationship of the exercise performance with risk of incident atrial fibrillation and its subsequent comorbidities. Methods From 2003 to 2012, we retrospectively included 19,680 consecutive patients without previous diagnosis of AF, who were referred to exercise treadmill testing for clinical reasons. The baseline characteristics and the exercise parameters during exercise testing were accessed in all enrolled subjects. Multivariable Cox proportional hazard models identified the independent association between exercise performance and risk of new-onset atrial fibrillation, risk of ischemic stroke and major adverse cardiovascular events (MACE). Cubic spline regression model assessed the risk of new-onset AF across fitness level. Results Among a total of 15,450 subjects (mean age, 54.9 ± 11 years; 59% male) with a median follow-up duration of 137 months, 515 (3.33%) new-onset AF cases were found. There was an 8% lower risk of AF incidence (hazard ratio, 0.92; 95% confidence interval, 0.88-0.97), a 12% lower risk of ischemic stroke incidence (hazard ratio, 0.88; 95% confidence interval, 0.83-0.94), and a 14% lower risk of MACE (hazard ratio, 0.86; 95% confidence interval, 0.84-0.88) for every 1 peak achieved metabolic equivalents (METs) increase in the exercise treadmill testing after adjusting confounding factors. In the subgroup analysis, the peak achieved METs during exercise treadmill testing was significantly associated with the risk of new-onset AF across various subgroups, including age, gender, body mass index (BMI) and underlying diseases. There were significant interactions in age subgroup (P for interaction 0.0047) and subgroup stratified by the presence of chronotropic incompetence (P for interaction 0.0212). Conclusions Exercise capacity is inversely correlated with AF incidence across fitness level. A better exercise performance indicates a lower AF incidence, ischemic stroke incidence and MACE. Regular physical activity may help to reduce inflammation and improve the function of the heart, which may help to prevent the development of AF. Further research is needed to fully understand the underlying mechanisms.Kaplan–Meier curveSubgroup analysis

Characterization and prognostic importance of chronotropic incompetence in heart failure with preserved ejection fraction

BackgroundExercise intolerance is the primary symptom of patients with heart failure with preserved ejection fraction (HFpEF). Chronotropic incompetence has been considered to be common and contribute to poor exercise capacity in HFpEF. However, clinical characteristics, pathophysiology, and outcomes of chronotropic incompetence in HFpEF remain poorly understood. MethodsPatients with HFpEF (n = 246) underwent ergometry exercise stress echocardiography with simultaneous expired gas analysis. The patients were divided into two groups based on the presence of chronotropic incompetence, which was defined by heart rate reserve <0.80. ResultsChronotropic incompetence was common in HFpEF (n = 112, 41 %). Compared to HFpEF patients with a normal chronotropic response (n = 134), those with chronotropic incompetence had higher body mass index, a higher prevalence of diabetes, more frequent β-blocker use, and worse New York Heart Association class. During peak exercise, patients with chronotropic incompetence demonstrated less increase in cardiac output and arterial oxygen delivery (cardiac output × saturation × hemoglobin × 1.34 × 10), higher metabolic work (peak oxygen consumption [VO2]/watt), an inability to increase arteriovenous oxygen difference, and poorer exercise capacity (lower peak VO2) than those without. Chronotropic incompetence was associated with higher rates of a composite of all-cause mortality or worsening HF events (hazard ratio, 2.66, 95 % confidence intervals, 1.16–6.09, p = 0.02). ConclusionChronotropic incompetence is common in HFpEF, and is associated with unique pathophysiologic characteristics during exercise and clinical outcomes.

Chronotropic incompetence in end-stage liver disease.

BackgroundCirrhosis causes alterations in the cardiovascular and autonomic nervous systems and leads to cirrhotic cardiomyopathy (CCM). CCM is defined as cardiac dysfunction characterized by an impaired systolic responsiveness to stress or exercise, and/or impaired diastolic function, as well as electrophysiological abnormalities, including chronotropic incompetence (CI), in the absence of other known cardiac disease. CI is a common feature of autonomic neuropathy in cirrhosis. The aim of the study is to assess the role of cardiac exercise stress test in the diagnosis of CCM.MethodsThe analysis included 160 end-stage liver disease (ESLD) patients who underwent a cardiac exercise stress test prior to the orthotopic liver transplantation. CI was defined as the inability to achieve the heart rate reserve (HRR). Pertaining to the therapy with beta-blockers: 80% of HRR was achieved in patients not taking beta-blockers and 62% in patients taking beta-blockers.ResultsIn the analyzed population, 68.8% of patients met the criteria for CI. CI was more frequent in the more severe ESLD (with a higher MELD score and in a higher Child-Pugh class). In comparison to the viral hepatitis and other etiologies of ESLD, patients with alcoholic cirrhosis had a significantly lower rest heart rate (HR), lower maximal HR, lower median achieved percentage of maximal predicted HR (MPHR), a smaller percentage of patients achieved ≥ 85% of MPHR and a lower heart rate reserve. No significant relationship between the survival of OLT recipients and presence of chronotropic incompetence regarding to class of Child-Pugh scale, MELD score and etiology of ESLD were found.ConclusionsThe prevalence of CI is higher among liver transplant candidates than previously described. The altered chronotropic response may differ in regard to the severity of liver disease correlating with both the Child-Pugh and MELD scores, however CI does not seem to influence the long-term survival post OLT. Exercise stress test is a reliable, safe and useful tool for the diagnosis of CCM in liver transplant candidates and should be included in the standard cardiovascular assessment prior to OLT.

Chronotropic Incompetence Limits Aerobic Exercise Capacity in Patients Taking Beta-Blockers: Real-Life Observation of Consecutive Patients.

Background: Chronotropic incompetence in patients taking beta-blockers is associated with poor prognosis; however, its impact on exercise capacity (EC) remains unclear. Methods: We analyzed data from consecutive patients taking beta-blockers referred for cardiopulmonary exercise testing to assess EC. Chronotropic incompetence was defined as chronotropic index (CI) ≤ 62%. Results: Among 140 patients all taking beta-blockers (age 61 ± 9.7 years; 73% males), 64% with heart failure, chronotropic incompetence was present in 80.7%. EC assessed as peak oxygen uptake was lower in the group with chronotropic incompetence, 18.3 ± 5.7 vs. 24.0 ± 5.3 mL/kg/min, p < 0.001. EC correlated positively with CI (β = 0.14, p < 0.001) and male gender (β = 5.12, p < 0.001), and negatively with age (β = −0.17, p < 0.001) and presence of heart failure (β = −3.35, p < 0.001). Beta-blocker dose was not associated with EC. Partial correlation attributable to CI accounted for more than one-third of the variance in EC explained by the model (adjusted R2 = 59.8%). Conclusions: In patients taking beta-blockers, presence of chronotropic incompetence was associated with lower EC, regardless of the beta-blocker dose. CI accounted for more than one-third of EC variance explained by our model.

Abstract 16002: Chronotropic Incompetence Limits Exercise Capacity in Patients Taking Beta-Blockers

Introduction: Chronotropic incompetence in patients taking beta-blockers is associated with poor prognosis; however, its impact on exercise capacity (EC) remains unclear. Hypothesis: We assessed the hypothesis that chronotropic incompetence is associated with decreased exercise capacity in patients taking beta-blockers. Methods: We retrospectively analyzed data from consecutive patients taking beta-blockers referred for cardiopulmonary exercise testing. EC was expressed as peak oxygen uptake (VO 2 peak; mL/kg/min). Chronotropic incompetence was defined as chronotropic index (CI) ≤ 62%. CI was calculated as [(HR at peak-resting HR) / (maximum predicted HR-resting HR)] х 100%. Results: Among 140 patients all taking beta-blockers (age 61 ± 9.7 years; 73% males), there were 113 (80.7%) patients with chronotropic incompetence. EC was lower in the group with chronotropic incompetence than the group without it, VO 2 peak 18.3 ± 5.7 vs. 24.0 ± 5.3 mL/kg/min, p &lt; 0.001. In multivariate analysis ( Table ), EC correlated positively with CI (β = 0.14, p &lt; 0.001) and male gender (β = 5.12, p &lt; 0.001), and negatively with age (β = –0.17, p &lt; 0.001) and presence of heart failure (β = –3.35, p &lt; 0.001). Beta-blocker dose was not associated with EC. Partial correlation attributable to CI (partial R 2 = 24.7%) accounted for more than one-third of the variance in EC explained by the model (adjusted R 2 = 59.8%). Conclusions: In patients taking beta-blockers, the presence of chronotropic incompetence was associated with lower EC, regardless of the beta-blocker dose. CI accounted for more than one-third of EC variance explained by our model.

Role And Determinants Of Chronotropic Incompetence In A Kidney Transplant Recipients Population

Hemodialysis patients reveal a significantly reduced exercise capacity, often associated with the presence of Chronotropic Incompetence (CI). Both these conditions are well known cardiovascular risk factors. Very limited data exists on CI in Kidney Transplant Recipients (KTRs). PURPOSE:To describe the prevalence of CI in a KTRs population and to analyze its potential determinants and its effects on functional capacity. METHODS: Consecutively recruited KTRs 3 months after transplantation underwent a Cardiopulmonary Exercise Test with an incremental protocol. 175 KTRs were included and the test was repeated in 60 subjects after a mean period of 22 months. Laboratory and drug therapy data were collected. CI was defined by the formula: MCI = (HRpeak-HRrest)/(HRpredicted-HRrest) / (V̇O2peak-V̇O2rest)/(V̇O2predicted-V̇O2rest) (MCI: metabolic chronotropic index, HR: heart rate, V̇O2: oxygen consumption). The prevalence of CI was calculated on 175 KTRs, while the multivariate regression analysis was conducted on 60 KTRs that repeated the test. RESULTS: In the whole population the CI prevalence was 30.9%. The 60 reassessed KTRs (age 51.6±1.3 years, 77% men) showed significant differences between 3 and 22 months after transplantation in the hemoglobin level (123.4±16.6 vs 136.4±17.8 g/L, p < 0.001) and in the proportion of beta-blocker therapy (50 vs 23.3%, p < 0.001), but no differences in V̇O2/kg peak (26.5±7.0 vs26.8±8.2 ml/kg/min, p = 0.85) nor in CI prevalence (31.7 vs 36.7, p = 0.41). KTRs with CI demonstrated no significant differences of V̇O2peak nor at 3 or at 22 months after transplantation, compared to KTRs without CI. The only determinant of CI at the two visits was the presence of arterial hypertension. Gender, age, BMI, the presence of diabetes, the type of immunosuppressive therapy, the duration of follow-up and beta-blocker therapy did not appear to be determinants of CI. CONCLUSIONS: KTRs are characterized by reduced functional capacity but the CI does not seem to significantly limit their functional level. In contrast to what it would be expected, beta-blocker therapy does not appear to be a CI determinant, while its only significant determinant was arterial hypertension.

Less is more: Can we achieve cardiac resynchronization with 2 leads only?

BackgroundWe compared clinical and technical outcome of CRT recipients treated either with a conventional 3‑leads (3L) CRTD or with the new 2‑leads (DX) CRTD that enables atrial signal detection by a floating dipole built on a pentafilar RV lead. MethodsEchocardiography and cardiopulmonary exercise tests were repeated either before CRTD implantation and between 6 and 12 months follow up in consecutively implanted patients who had a resting heart rate>40bpm at maximum tolerated beta-blocker dosage. HF status, reverse LV remodeling, exercise tolerance and chronotropic incompetence were assessed at 12 months FU. Device diagnostics were obtained twice yearly until December 2016. Results37 patients aged 66 (58–73) years were consecutively implanted in 2013–2014 according to current guidelines, 25 with a 3L CRTD and 12 with a DX CRTD. Beta-blocker dosage was similar, and no difference between the 2 groups was observed in terms of NYHA class improvement, LV reverse remodeling, peak cardiopulmonary performance and presence of chronotropic incompetence at 12 months follow up. There was no difference in: amount delivered CRT; occurrence of VT/VF; occurrence of AT/AF. No patients developed need of atrial stimulation at 3-years FU. Atrial undersensing never occurred in any patient, whereas Far-field R-wave oversensing was more common in 3L patient than in DX patients (8/25 vs none, P<0.05). P wave amplitude was greater in DX vs 3L patients [5.1(3.7–9.2) vs 2.9(2–3.9) mV, P<0.01]. ConclusionCRT can be achieved with two‑leads-only in the majority of patients, provided that indication to atrial stimulation is ruled out.

Impaired chronotropic response to physical activities in heart failure patients

BackgroundWhile exercise-based cardiac rehabilitation has a beneficial effect on heart failure hospitalization and mortality, it is limited by the presence of chronotropic incompetence (CI) in some patients. This study explored the feasibility of using wearable devices to assess impaired chronotropic response in heart failure patients.MethodsForty patients with heart failure (left ventricular ejection fraction, LVEF: 44.6 ± 5.8; age: 54.4 ± 11.7) received ECG Holter and accelerometer to monitor heart rate (HR) and physical activities during symptom-limited treadmill exercise testing, 6-min hall walk (6MHW), and 24-h daily living. CI was defined as maximal HR during peak exercise testing failing to reach 70% of age-predicted maximal HR (APMHR, 220 – age). The correlation between HR and physical activities in Holter-accelerometer recording was analyzed.ResultsOf 40 enrolled patients, 26 were able to perform treadmill exercise testing. Based on exercise test reports, 13 (50%) of 26 patients did not achieve at least 70% of APMHR (CI patients). CI patients achieved a lower % APMHR (62.0 ± 6.3%) than non-CI patients who achieved 72.0 ± 1.2% of APMHR (P < 0.0001). When Holter-accelerometer recording was used to assess chronotropic response, the percent APMHR achieved during 6MHW and physical activities was significantly lower in CI patients than in non-CI patients. CI patients had a significantly shorter 6MHW distance and less physical activity intensity than non-CI patients.ConclusionThe study found impaired chronotropic response in 50% of heart failure patients who took treadmill exercise testing. The wearable Holter-accelerometer recording could help to identify impaired chronotropic response to physical activities in heart failure patients.Trial registrationClinicalTrials.gov ID NCT02358603. Registered 16 May 2014.

Exercise Capacity Long-Term after Arterial Switch Operation for Transposition of the Great Arteries.

Transposition of the great arteries (TGA) is a congenital heart defect successfully corrected through arterial switch operation (ASO). Although this technique had significant impact in improving survival, little is known about the functional capacity of the operated patients long-term after surgery. The aim of this study was to compare the functional capacity of children with TGA long-term after ASO with that of healthy children. Retrospective study. All patients that performed cardiopulmonary exercise test (CPET) were included in the study. As a control group, healthy children in evaluation for physical activity that performed CPET during the same period were also enrolled. Thirty-one TGA patients (19 male) were compared with 29 age-matched controls (21 male). Maximum oxygen consumption was higher in the control group (45.47 ± 8.05 vs. 40.52 ± 7.19, P = .017), although within normal limits in both groups (above 90% of predicted value). The heart rate behavior during exercise was different in both groups, with a mean chronotropic index significantly lower in the TGA group (63% ± 14 vs. 81% ± 12, P < .001). Our results showed that exercise capacity long-term after ASO in TGA is well preserved although lower than in healthy children what might be explained by the presence of chronotropic incompetence in the TGA group.

Effect of β-Blocker Cessation on Chronotropic Incompetence and Exercise Tolerance in Patients With Advanced Heart Failure

Chronotropic incompetence is defined as the inability to reach 80% of heart rate (HR) reserve or 80% of the maximally predicted HR during exercise. The presence of chronotropic incompetence is associated with reduced peak oxygen consumption, and rate-responsive pacing therapy is under investigation to improve exercise capacity in heart failure (HF). However, uncertainty exists about whether chronotropic incompetence and reduced exercise tolerance in HF are attributable to β-blockade. Subjects with HF and receiving long-term β-blocker therapy underwent cardiopulmonary exercise tolerance testing under 2 conditions in random sequence: (1) after a 27-hour washout period (Off-BB) and (2) 3 hours after β-blocker ingestion (On-BB). Norepinephrine levels were drawn at rest and at peak exercise. β1-response to norepinephrine was assessed using the chronotropic responsiveness index: ΔHR/Δlog norepinephrine. Nineteen patients with systolic HF (left ventricular ejection fraction, 22.8±7.7%) were enrolled. Mean age was 49.4±12.3 years. Average carvedilol equivalent dose was 29.1±17.0 mg daily. Peak HR off/on β-blockers was 62.7±18.7% and 51.4±18.2% HR reserve (P<0.01) and 79.1±11.0% and 70.3±12.3% maximally predicted HR (P<0.01). For the Off-BB and On-BB conditions, the respiratory exchange ratios were 1.05±0.06 and 1.05±0.10 (P=0.77), respectively, confirming maximal and near identical effort in both conditions. The peak oxygen consumption was 16.6±3.34 and 15.9±3.31 mL/kg/min (P=0.03), and the chronotropic responsiveness index was 19.3±7.2 and 16.2±7.1 (P=0.18). Acute β-blocker cessation does not normalize the chronotropic response to exercise in patients with advanced HF and chronotropic incompetence.

Comparison of VVIR, DDD, and DDDR Pacing

In the past several years there has been continued improvement in pacemaker technology, resulting in the availability of a large variety of pacemaker generators and pacing modes. The introduction of single‐chamber rate modulated pacemakers provided a further improvement in pacing therapy. With the recent introduction of dual‐chamber rate responsive pacemakers, it is now possible to more closely restore physiological function with pacing in a large number of patients. In deciding which pacing mode is most beneficial to a given patient, it is essential to understand the various characteristics of the different pacing modes that are available. It is essential to have knowledge of the underlying electrophysiological characteristics of the patient and how they would be affected by the different modes available. The VVIR mode will control bradycardia and provide rate adaptation but at the expense of AV synchrony. The DDD mode will control bradycardia and provide AV synchrony, but will not provide rate adaptation in patients with chronotropic incompetence. The DDDR mode will control bradycardia, maintain AV synchrony, and provide far rate adaptation in the presence of chronotropic incompetence. The chronotropic response to physiological stress and/or pacemaker syndrome are major determining factors in the choice of the best pacing mode. The primary goal of pacing therapy is to restore the heart function as close as possible to normal. When at all possible, this should include provision of both AV synchrony and rate modulation. The DDDR mode is preferable in most patients since it is capable of providing both AV synchrony and rate response (except those with chronic supraventricular arrhythmias). The VVIR mode is as effective in patients who have chronic atrial fibrillation or frequent episodes of supraventricitar arrhythmias.