Testing an exercise intervention to improve aerobic conditioning and autonomic function after an implantable cardioverter defibrillator (ICD)

Exploring the feasibility and impact of positive psychology-motivational interviewing interventions to promote positive affect and physical activity in type 2 diabetes: design and methods from the BEHOLD-8 and BEHOLD-16 clinical trials

BACKGROUND

Physical activity among those with type 2 diabetes (T2D) is independently associated with superior medical outcomes, but existing behavioral interventions have not led to widespread increases in activity in this population. A remotely delivered intervention that targets well-being constructs associated with greater activity and assists in the creation of specific physical activity goals has the potential to improve activity and outcomes in T2D.

OBJECTIVE

To outline the rationale and methods of two studies designed to assess the impact and optimal duration of a combined positive psychology-motivational interviewing (PP-MI) intervention for inactive persons with T2D.

METHODS

We conducted trials studying 8-week (BEHOLD-8;) and 16-week (BEHOLD-16;) phone-delivered interventions, compared to attention-matched control conditions. In a two-step randomization design, participants were allocated randomly first to study (BEHOLD-8 or BEHOLD-16), then to study condition within study. The primary aims in both trials were feasibility (rates of session completion) and acceptability (participant session ratings), with additional aims examining intervention effects on accelerometer-measured physical activity, psychological measures, and health-related metrics (e.g. vital signs). Main analyses, currently being conducted, will utilize mixed effects models between study conditions, and secondary analyses will utilize the same models to compare the 8- and 16-week PP-MI interventions on feasibility and impact.

RESULTS

Enrollment and data collection have been completed for both trials (BEHOLD-8: N = 60; BEHOLD-16: N = 70), and data analysis is ongoing to assess feasibility and acceptability within study, as well as the relative feasibility and acceptability of the PP-MI interventions across the two studies. We will also explore impact on clinical outcomes between groups.

CONCLUSIONS

This design will address how intervention content (i.e. PP elements vs. no PP elements) and intervention duration (8 weeks vs. 16 weeks) affect feasibility, acceptability, and impact, allowing intervention optimization before a next-step larger clinical trial.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03150199; NCT03001999.

Exercise-based cardiac rehabilitation for adult patients with an implantable cardioverter defibrillator

BACKGROUND

An effective way of preventing sudden cardiac death is the use of an implantable cardioverter defibrillator (ICD). In spite of the potential mortality benefits of receiving an ICD device, psychological problems experienced by patients after receiving an ICD may negatively impact their health-related quality of life, and lead to increased readmission to hospital and healthcare needs, loss of productivity and employment earnings, and increased morbidity and mortality. Evidence from other heart conditions suggests that cardiac rehabilitation should consist of both exercise training and psychoeducational interventions; such rehabilitation may benefit patients with an ICD. Prior systematic reviews of cardiac rehabilitation have excluded participants with an ICD. A systematic review was therefore conducted to assess the evidence for the use of exercise-based intervention programmes following implantation of an ICD.

OBJECTIVES

To assess the benefits and harms of exercise-based cardiac rehabilitation programmes (exercise-based interventions alone or in combination with psychoeducational components) compared with control (group of no intervention, treatment as usual or another rehabilitation programme with no physical exercise element) in adults with an ICD.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase and four other databases on 30 August 2018 and three trials registers on 14 November 2017. We also undertook reference checking, citation searching and contacted study authors for missing data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) if they investigated exercise-based cardiac rehabilitation interventions compared with no intervention, treatment as usual or another rehabilitation programme. The trial participants were adults (aged 18 years or older), who had been treated with an ICD regardless of type or indication.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed risk of bias. The primary outcomes were all-cause mortality, serious adverse events and health-related quality of life. The secondary outcomes were exercise capacity, antitachycardia pacing, shock, non-serious adverse events, employment or loss of employment and costs and cost-effectiveness. Risk of systematic errors (bias) was assessed by evaluation of predefined bias risk domains. Clinical and statistical heterogeneity were assessed. Meta-analyses were undertaken using both fixed-effect and random-effects models. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We identified eight trials published from 2004 to 2017 randomising a total of 1730 participants, with mean intervention duration of 12 weeks. All eight trials were judged to be at overall high risk of bias and effect estimates are reported at the end of the intervention with a follow-up range of eight to 24 weeks.Seven trials reported all-cause mortality, but deaths only occurred in one trial with no evidence of a difference between exercise-based cardiac rehabilitation and control (risk ratio (RR) 1.96, 95% confidence interval (CI) 0.18 to 21.26; participants = 196; trials = 1; quality of evidence: low). There was also no evidence of a difference in serious adverse events between exercise-based cardiac rehabilitation and control (RR 1.05, 95% CI 0.77 to 1.44; participants = 356; trials = 2; quality of evidence: low). Due to the variation in reporting of health-related quality of life outcomes, it was not possible to pool data. However, the five trials reporting health-related quality of life at the end of the intervention, each showed little or no evidence of a difference between exercise-based cardiac rehabilitation and control.For secondary outcomes, there was evidence of a higher pooled exercise capacity (peak VO₂) at the end of the intervention (mean difference (MD) 0.91 mL/kg/min, 95% CI 0.60 to 1.21; participants = 1485; trials = 7; quality of evidence: very low) favouring exercise-based cardiac rehabilitation, albeit there was evidence of substantial statistical heterogeneity (I² = 78%). There was no evidence of a difference in the risk of requiring antitachycardia pacing (RR 1.26, 95% CI 0.84 to 1.90; participants = 356; trials = 2; quality of evidence: moderate), appropriate shock (RR 0.56, 95% CI 0.20 to 1.58; participants = 428; studies = 3; quality of evidence: low) or inappropriate shock (RR 0.60, 95% CI 0.10 to 3.51; participants = 160; studies = 1; quality of evidence: moderate).

AUTHORS' CONCLUSIONS

Due to a lack of evidence, we were unable to definitively assess the impact of exercise-based cardiac rehabilitation on all-cause mortality, serious adverse events and health-related quality of life in adults with an ICD. However, our findings do provide very low-quality evidence that patients following exercise-based cardiac rehabilitation experience a higher exercise capacity compared with the no exercise control. Further high-quality randomised trials are needed in order to assess the impact of exercise-based cardiac rehabilitation in this population on all-cause mortality, serious adverse events, health-related quality of life, antitachycardia pacing and shock.

Prospective randomized trial of moderately strenuous aerobic exercise after an implantable cardioverter defibrillator

BACKGROUND

Despite its salutary effects on health, aerobic exercise is often avoided after receipt of an implantable cardioverter defibrillator (ICD) because of fears that exercise may provoke acute arrhythmias. We prospectively evaluated the effects of a home aerobic exercise training and maintenance program (EX) on aerobic performance, ICD shocks, and hospitalizations exclusively in ICD recipients.

METHODS AND RESULTS

A total of 160 patients (124 men and 36 women) were randomly assigned who had an ICD for primary (43%) or secondary (57%) prevention to EX or usual care (UC). The primary outcome was peak oxygen consumption, measured with cardiopulmonary exercise testing at baseline and 8 and 24 weeks. EX consisted of 8 weeks of home walking for 1 h/d, 5 d/wk at 60% to 80% of heart rate reserve, followed by 16 weeks of maintenance home walking for 150 min/wk. Adherence to EX was determined from exercise logs, ambulatory heart rate recordings of exercise, and weekly telephone contacts. Patients assigned to UC received no exercise directives and were monitored by monthly telephone contact. Adverse events were identified by ICD interrogations, patient reports, and medical charts. ICD recipients averaged 55±12 years and mean ejection fraction of 40.6±15.7; all were taking β-blocker medications. EX significantly increased peak oxygen consumption (EX, 26.7±7.0 mL/kg per minute; UC, 23.9±6.6 mL/kg per minute; P=0.002) at 8 weeks, which persisted during maintenance exercise at 24 weeks (EX, 26.9±7.7 mL/kg per minute; UC, 23.4±6.0 mL/kg per minute; P<0.001). ICD shocks were infrequent (EX=4 versus UC=8), with no differences in hospitalizations or deaths between groups.

CONCLUSIONS

Prescribed home exercise is safe and significantly improves cardiovascular performance in ICD recipients without causing shocks or hospitalizations.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00522340.

Development and safety of an exercise testing protocol for patients with an implanted cardioverter defibrillator for primary or secondary indication

PURPOSE

Performing exercise tests in patients with an implantable cardioverter defibrillator (ICD) presents specific challenges because of susceptibility to ventricular arrhythmias during maximal levels of exertion. The purpose of this paper is to outline the exercise testing protocol from the Anti-Arrhythmic Effects of Exercise after an ICD trial and to report baseline test results and safety outcomes using the protocol.

METHODS AND RESULTS

Maximal cardiopulmonary exercise testing was performed to assess levels of physical fitness as part of a randomized trial of walking exercise in patients with ICDs. Subjects were randomized after baseline testing to aerobic exercise plus usual care or usual care alone. A modified Balke treadmill exercise test was used and specific ICD programming procedures were implemented to avoid unnecessary shocks, which included programming off ventricular tachycardia (VT) therapies during testing. To date, 161 baseline tests have been performed. One ventricular fibrillation (VF) cardiac arrest occurred following completion of an exercise test and three tests were stopped by the investigators due to nonsustained ventricular tachycardia. Eleven subjects were not able to achieve maximum exercise, defined as reaching an anaerobic threshold (AT) at baseline testing. There have been no deaths as a result of exercise testing.

CONCLUSIONS

Symptom-limited maximal exercise testing can be performed safely and effectively in patients with ICDs for both primary and secondary prevention indications. Specific strategies for ICD programming and preparation for treating ventricular arrhythmias needs to be in place before exercise testing is performed.

Physical activity patterns of patients with cardiopulmonary illnesses

OBJECTIVES

The aims of this paper were (1) to describe objectively confirmed physical activity patterns across 3 chronic cardiopulmonary conditions, and (2) to examine the relationship between selected physical activity dimensions with disease severity, self-reported physical and emotional functioning, and exercise performance.

DESIGN

Cross-sectional study.

SETTING

Participants' home environment.

PARTICIPANTS

Patients with cardiopulmonary illnesses: chronic obstructive pulmonary disease (COPD) (n=63), heart failure (n=60), and patients with implantable cardioverter defibrillator (n=60).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Seven ambulatory physical activity dimensions (total steps, percent time active, percent time ambulating at low, medium, and high intensity, maximum cadence for 30 continuous minutes, and peak performance) were measured with an accelerometer.

RESULTS

Subjects with COPD had the lowest amount of ambulatory physical activity compared with subjects with heart failure and cardiac dysrhythmias (all 7 activity dimensions, P<.05); total step counts were: 5319 versus 7464 versus 9570, respectively. Six-minute walk distance was correlated (r=.44-.65, P<.01) with all physical activity dimensions in the COPD sample, the strongest correlations being with total steps and peak performance. In subjects with cardiac impairment, maximal oxygen consumption had only small to moderate correlations with 5 of the physical activity dimensions (r=.22-.40, P<.05). In contrast, correlations between 6-minute walk test distance and physical activity were higher (r=.48-.61, P<.01) albeit in a smaller sample of only patients with heart failure. For all 3 samples, self-reported physical and mental health functioning, age, body mass index, airflow obstruction, and ejection fraction had either relatively small or nonsignificant correlations with physical activity.

CONCLUSIONS

All 7 dimensions of ambulatory physical activity discriminated between subjects with COPD, heart failure, and cardiac dysrhythmias. Depending on the research or clinical goal, use of 1 dimension, such as total steps, may be sufficient. Although physical activity had high correlations with performance on a 6-minute walk test relative to other variables, accelerometry-based physical activity monitoring provides unique, important information about real-world behavior in patients with cardiopulmonary illness not already captured with existing measures.