Autonomic dysfunction predicts poor physical improvement after cardiac rehabilitation in patients with heart failure

Background: Cardiac autonomic dysfunction, clinically expressed by reduced heart rate variability (HRV), is present in patients with congestive heart failure (CHF) and is related to the degree of left ventricular dysfunction. In athletes, HRV is an indicator of ability to improve performance. No similar data are available for CHF. Objectives: The aim of this study was to assess whether HRV could predict the capability of CHF patients to improve physical fitness after a short period of exercise-based cardiac rehabilitation (CR). Patients and Methods: This was an observational, non-randomized study, conducted on 57 patients with advanced CHF, admitted to a residential cardiac rehabilitation unit 32 ± 22 days after an episode of acute heart failure. Inclusion criteria were sinus rhythm, stable clinical conditions, no diabetes and ejection fraction = 35%. HRV (time-domain) and mean and minimum heart rate (HR) were evaluated using 24-h Holter at admission. Patients' physical fitness was evaluated at admission by 6-minute walking test (6MWT) and reassessed after two weeks of intensive exercise-based CR. Exercise capacity was evaluated by a symptom-limited cardiopulmonary exercise test (CPET). Results: Patients with very depressed HRV (SDNN 55.8 ± 10.0 ms) had no improvement in their walking capacity after short CR, walked shorter absolute distances at final 6MWT (348 ± 118 vs. 470 ± 109 m; P = 0.027) and developed a peak-VO2 at CPET significantly lower than patients with greater HRV parameters (11.4 ± 3.7 vs. an average > 16 ± 4 mL/kg/min). Minimum HR, but not mean HR, showed a negative correlation (ρ = -0.319) with CPET performance. Conclusions: In patients with advanced CHF, depressed HRV and higher minimum HR were predictors of poor working capacity after a short period of exercise-based CR. An individualized and intensive rehabilitative intervention should be considered for these patients

Abnormal heart rate variability and atrial fibrillation after aortic surgery

Introduction: Complete denervation of transplanted heart exerts protective effect against postoperative atrial fibrillation; various degrees of autonomic denervation appear also after transection of ascending aorta during surgery for aortic aneurysm. Objective: This study aimed to evaluate if the level of cardiac denervation obtained by resection of ascending aorta could exert any effect on postoperative atrial fibrillation incidence. Methods: We retrospectively analysed the clinical records of 67 patients submitted to graft replacement of ascending aorta (group A) and 132 with aortic valve replacement (group B); all episodes of postoperative atrial fibrillation occurred during the 1-month follow-up have been reported. Heart Rate Variability parameters were obtained from a 24-h Holter recording; clinical, echocardiographic and treatment data were also evaluated. Results: Overall, 45% of patients (group A 43%, group B 46%) presented at least one episode of postoperative atrial fibrillation. Older age (but not gender, abnormal glucose tolerance, ejection fraction, left atrial diameter) was correlated with incidence of postoperative atrial fibrillation. Only among a subgroup of patients with aortic transection and signs of greater autonomic derangement (heart rate variability parameters below the median and mean heart rate over the 75th percentile), possibly indicating more profound autonomic denervation, a lower incidence of postoperative atrial fibrillation was observed (22% vs. 54%). Conclusion: Transection of ascending aorta for repair of an aortic aneurysm did not confer any significant protective effect from postoperative atrial fibrillation in comparison to patients with intact ascending aorta. It could be speculated that a limited and heterogeneous cardiac denervation was produced by the intervention, creating an eletrophysiological substrate for the high incidence of postoperative atrial fibrillation observed

Depressive symptoms, functional measures and long-term outcomes of high-risk ST-elevated myocardial infarction patients treated by primary angioplasty

The presence of major depressive symptoms is usually considered a negative long-term prognostic factor after an acute myocardial infarction (AMI); however, most of the supporting research was conducted before the era of immediate reperfusion by percutaneous coronary intervention. The aims of this study are to evaluate if depression still retains long-term prognostic significance in our era of immediate coronary reperfusion, and to study possible correlations with clinical parameters of physical performance. In 184 patients with recent ST-elevated AMI (STEMI), treated by immediate reperfusion, moderate or severe depressive symptoms (evaluated by Beck Depression Inventory version I) were present in 10 % of cases. Physical performance was evaluated by two 6-min walk tests and by a symptom-limited cardiopulmonary exercise test: somatic/affective (but not cognitive/affective) symptoms of depression and perceived quality of life (evaluated by the EuroQoL questionnaire) are worse in patients with lower levels of physical performance. Follow-up was performed after a median of 29 months by means of telephone interviews; 32 major adverse cardiovascular events (MACE) occurred. The presence of three vessels disease and low left ventricle ejection fraction are correlated with a greater incidence of MACE; only somatic/affective (but not cognitive/affective) symptoms of depression correlate with long-term outcomes. In patients with recent STEMI treated by immediate reperfusion, somatic/affective but not cognitive/affective symptoms of depression show prognostic value on long-term MACE. Depression symptoms are not predictors "per se" of adverse prognosis, but seem to express an underlying worse cardiac efficiency, clinically reflected by poorer physical performance

A practical review for cardiac rehabilitation professionals of continuous-flow left ventricular assist devices: Historical and current perspectives

An increasing number of patients with end-stage heart failure are being treated with continuous-flow left ventricular assist devices (cf-LVADs). These patients provide new challenges to the staff in exercise-based cardiac rehabilitation (CR) programs. Even though experience remains limited, it seems that patients supported by cf-LVADs may safely engage in typical rehabilitative activities, provided that some attention is paid to specific aspects, such as the presence of a short external drive line. In spite of initial physical deconditioning, CR allows progressive improvement of symptoms such as fatigue and dyspnea. Intensity of rehabilitative activities should ideally be based on measured aerobic capacity and increased appropriately over time. Regular, long-term exercise training results in improved physical fitness and survival rates. Appropriate adjustment of cf-LVAD settings, together with maintenance of adequate blood volume, provides maximal output, while avoiding suction effects. Ventricular arrhythmias, although not necessarily constituting an immediate life-threatening situation, deserve treatment as they could lead to an increased rate of hospitalization and poorer quality of life. Atrial fibrillation may worsen symptoms of right ventricular failure and reduce exercise tolerance. Blood pressure measurements are possible in cf-LVAD patients only using a Doppler technique, and a mean blood pressure 80 mmHg is considered ideal. Some patients may present with orthostatic intolerance, related to autonomic dysfunction. While exercise training constitutes the basic rehabilitative tool, a comprehensive intervention that includes psychological and social support could better meet the complex needs of patients in which cf-LVAD may offer prolonged surviva

Functional parameters but not heart rate variability correlate with long-term outcomes in St-elevation myocardial infarction patients treated by primary angioplasty

BACKGROUND: Depressed heart rate variability (HRV) is usually considered a negative long-term prognostic factor after acute myocardial infarction. Anyway, most of the supporting research was conducted before the era of immediate reperfusion by percutaneous coronary intervention (PCI). Main aim of this study was to evaluate if HRV still retains prognostic significance in our era of immediate PCI. METHODS AND RESULTS: Two weeks after STEMI treated by primary PCI, time-domain HRV was assessed from 24-h Holter recordings in 186 patients: markedly depressed HRV (SDNN 2years from infarction, occurrence of major clinical events (MCE) was investigated. Cases with or without MCE did not differ by initial HRV parameters; Kaplan-Meier events-free survival curves were similar between patients with lowest quartile SDNN and the remaining ones (\u3c72 0.981, p=0.322). By the contrary, events-free survival was worse if patients walked shorter distances at 6MWT (\u3c72 6.435, p=0.011), developed poorer ventilatory efficiency at CPET (\u3c72 10.060, p=0.002), or presented LVEF <40% (\u3c72 7.085, p=0.008). CONCLUSIONS: In primary-PCI STEMI patients, markedly abnormal HRV was found in a small percentage of cases. HRV seems to have lost its prognostic significance, while parameters indicating LV function (LVEF and physical performance) could allow better prognostication in primary-PCI STEMI patients

Impact of type of intervention for aortic valve replacement on heart rate variability

Background: It is known that coronary heart surgery leads to varying degrees of cardiac autonomic derangement, clinically detectable as depression of heart rate variability (HRV) parameters. Fewstudies report that also surgical replacement of the aortic valve (SAVR) may lead to HRV abnormalities, while very little is known about the autonomic effects obtained after less invasive aortic valve replacement techniques. The study aimed to evaluate HRV after SAVR and to compare it with two less invasive techniques, transapical (TaAVI) and tranfemoral (TfAVI) aortic valve implant. Methods: Time-domain heart rate variability (HRV) parameters have been studied by 24-h Holter ECG in 129 patients after SAVR, in 63 patients after TfAVI and in 19 patients after TaAVI. Results: All HRV parameters were significantly depressed in SAVR, while theywere almost completely preserved in TfAVI patients; TaAVI cases showed a somehow intermediate behaviour [(SDNN respectively: 71.0 +/- 34.9 vs 95.9 +/- 29.5 (p < 0.001) vs 84.4 +/- 32.6 ms (p-ns)]. Mean heart rate during the 24-h Holter was 8% higher in SAVR patients than in both TfAVI and TaAVI patients. The reported results were not correlated with echocardio-graphic ejection fraction, or presence of abnormal glucose metabolism, or degree of anaemia or treatment with beta-blockers. Conclusions: SAVR leads to profound depression of some cardiac autonomic parameters, while less invasive procedures allowbetter preservation of HRV. In particular TfAVI does not induce any significant deterioration of HRV parameters and seems to be the strategy of valve implant with less impact on the cardiovascular autonomic system

Cardiac autonomic dysfunction in the early phase after left ventricular assist device implant: Implications for surgery and follow-up

Purpose In congestive heart failure (CHF) patients, a profound cardiac autonomic derangement, clinically expressed by reduced heart rate variability (HRV), is present and is related to the degree of ventricular dysfunction. Implantation of a left ventricular assist device (LVAD) can progressively improve HRV, associated with an increased circulatory output. Data from patients studied at different times after LVAD implantation are controversial. The aims of this study were to assess cardiac autonomic function in the early phases after axial-flow LVAD implantation, and to estimate the potential relevance of recent major surgical stress on the autonomic balance. Methods HRV (time-domain; 24-h Holter) was evaluated in 14 patients, 44.8 ± 25.8 days after beginning of Jarvik-2000 LVAD support; 47 advanced stage CHF, 24 cardiac surgery (CS) patients and 30 healthy subjects served as control groups. Inclusion criteria: sinus rhythm, stable clinical conditions, no diabetes or other known causes of HRV alteration. Results HRV was considerably reduced in LVAD patients in the early phases after device implantation in comparison to all control groups. A downgrading of HRV parameters was also present in CS controls. Circadian oscillations were highly depressed in LVAD and CHF patients, and slightly reduced in CS patients. Conclusions In CHF patients supported by a continuous-flow LVAD, a profound cardiac dysautonomia is still evident in the first two months from the beginning of circulatory support; the degree of cardiac autonomic imbalance is even greater in comparison to advanced CHF patients. The recent surgical stress could be partly linked to these abnormalities. </jats:sec