Maximizing Patient Benefit From Cardiac Resynchronization Therapy With the Addition of Structured Exercise Training - Maximizing Patient Benefit From Cardiac Resynchronization Therapy With the Addition of Structured Exercise Training

Jul 03, 2009
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Date Published:
01/01/2009
Date Updated:
07/03/2009
Original Posted Date:
07/03/2009
References

Description:

Exercise training has been shown to be beneficial in patients with chronic systolic heart failure. Cardiac resynchronization therapy (CRT) has also been shown to benefit patients with New York Heart Association (NYHA) class III or IV heart failure. This trial sought to study whether the addition of exercise training to CRT would lead to further improvements in peak VO2 in these patients.

Hypothesis:

Exercise training would result in further improvements in peak VO2 in patients with chronic systolic heart failure receiving a CRT device.

Study Design

Study Design:

Patients Screened: 50
Patients Enrolled: 50
Mean Follow Up: 6 months
Mean Patient Age: 64.4 years
Female: 8
Mean Ejection Fraction: 23.7%

Patient Populations:

  • Optimal medical therapy for congestive heart failure
  • Stable medical condition for ≥1 month
  • Fulfill criteria for CRT (NYHA class III or IV, QRS duration >120 ms, LVEF <35%)

Exclusions:

  • Noncardiac physical limitations, such as chronic obstructive pulmonary disease, recent myocardial infarction, arthritis
  • Coronary artery bypass grafting/percutaneous coronary intervention within 3 months, or planned in the near future
  • Significant untreated valvular heart disease

Primary Endpoints:

Peak VO2 at 6 months

Drug/Procedures Used:

Three months after CRT implantation, patients were randomized into an exercise group and a control group. The exercise group underwent a program of physician-supervised exercise training consisting of three 30-minute visits/week. Each session consisted of 10-minute treadmill walking followed by 10-minute cycling, and then a further 10-minute treadmill walking. The intensity was 80% of the peak heart rate (HR) achieved at the 3-month test for the first 4 weeks, 85% for the next 4 weeks, and 90% for the final 4 weeks.

The exercise group was not provided with any specific instruction or guidance to perform exercise outside of the study. The control group was given no specific advice on exercise training and underwent no supervised training.

Concomitant Medications:

Angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers (98.0%), beta-blockers (60%), digoxin (46%), and spironolactone (54%)

Principal Findings:

A total of 50 patients were randomized, 25 to each arm. Baseline characteristics were fairly similar. Patients had predominantly NYHA functional class III congestive heart failure, with a mean peak VO2 of 16.1 ml/kg/min, and exercise capacity of 374 seconds. Mean QRS duration was 160 ms, with a mean left ventricular end-diastolic diameter (LVEDD) of 7.1 cm and an ejection fraction (EF) of 24.0%. Sinus rhythm was noted in 66% of the patients.

Three months after CRT, there was a significant improvement in mean peak VO2 to 18.4 ± 3.6 (p < 0.001), and exercise duration to 562 seconds (p < 0.001). Cardiac indices such as peak cardiac power output and cardiac reserve also improved; however, peak VO2 at the anaerobic threshold remained unchanged. Echocardiographic parameters such as LVEDD (7.07 ± 0.87 vs. 6.64 ± 0.77 cm, p < 0.001) and LVEF (23.7 ± 8.7 vs. 32.4 ± 6.2%, p < 0.001) were also significantly improved, while quality of life also improved.

Six months after CRT, the exercise arm was noted to have higher exercise duration (mean change: 171 vs. 30 seconds, p < 0.001), peak VO2 (mean change 1.39 vs. -0.01, p = 0.022), with further improvements in quality of life, as compared with the standard therapy arm. Although significantly changed from baseline in both arms, there was no difference between the two arms at 6 months in LVEDD or LVEF. No side effects relating to exercise or arrhythmias were noted in the exercise arm.

Interpretation:

The American College of Cardiology/American Heart Association guidelines currently recommend exercise training for all patients with chronic systolic heart failure, and its benefits were confirmed in the recently published HF-ACTION trial. Similarly, the beneficial effects of CRT on exercise capacity in these patients have been noted before. The results of this small, single-center, randomized, controlled trial indicate that exercise training in addition to CRT may be associated with even greater symptomatic and exercise capacity benefits in patients with chronic systolic heart failure.

Further follow-up may be necessary to document improvements in echocardiographic parameters such as LVEDD and LVEF. This is a simple, cost-effective, and safe intervention, and should be recommended in all such patients.

References:

Patwala A, Woods PR, Sharp L, Goldspink DF, Tan LB, Wright DJ. Maximizing patient benefit from cardiac resynchronization therapy with the addition of structured exercise training: a randomized controlled study. J Am Coll Cardiol 2009;53:2332-9.

Keywords: Walking, Follow-Up Studies, Quality of Life, Anaerobic Threshold, Cardiac Output, Heart Rate, Heart Failure, Systolic, Defibrillators, Implantable, Cardiac Resynchronization Therapy, Exercise Test


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