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Providing heart-failure patients with a structured exercise program on top of cardiac resynchronization therapy (CRT) boosts the functional and hemodynamic improvements of biventricular pacing, prompting investigators to suggest it is reasonable to provide exercise programs to all patients after CRT [1].

"Cardiac resynchronization normally improves their status by one New York Heart Association [NYHA] classification, and with that they feel better and their quality of life improves," senior investigator Dr David Wright (Liverpool Heart and Chest Hospital, UK) told heartwire . "They can then exercise a bit more. We felt that because they have the benefit from improved circulation from the pacemaker, the peripheral changes due to long-term lack of exercise can be reversed. We thought that exercise on top of their pacemaker would add extra benefit, and that's exactly what this research shows."

The study, published in the June 23, 2009 issue of the Journal of the American College of Cardiology, included 50 patients referred for CRT. Functional class and quality-of-life scores were assessed and exercise tests with hemodynamic measures performed, before implantation and at three months. At three months, patients were randomized to the structured exercise program or to the control group.

Patients randomized to the exercise program underwent a 12-week program of physician-supervised exercise training three times per week for 30 minutes. The session consisted of walking 10 minutes on the treadmill, cycling for 10 minutes, and then an additional 10 minutes of walking. Intensity increased from 80% of peak heart rate in the first month to 90% in the last month.

Three months after CRT implantation, there were significant improvements in functional, hemodynamic, and echocardiographic measures. After randomization, however, patients in the exercise arm had further improvements in NYHA functional class, exercise hemodynamic measures, and quality-of-life scores.

Exercise and Hemodynamic Results After Randomization

Measure	Exercise, 3 mo	Exercise, 6 mo	Change	Control, 3 mo	Control, 6 mo	Change
NYHA functional class	2	1a	1b	2	2	--
Exercise duration (s)	581	752a	17 b	542	572a	30
Peak VO2 (mL/kg/min)	18.74	20.10a	1.37b	18.08	18.07	-0.01
Ejection fraction	32.8	37.3a	4.5	32.6	35.0	2.5
Left ventricular end-diastolic dimension (cm)	6.64	6.40	-0.20	6.57	6.34a	-0.23
Minnesota Living with Heart Failure score	34.6	26.2a	-8.4b	29.0	29.5	1.6

a. p<0.05 compared with 3 months
b. p<0.05>

"In this group of patients, we've seen almost a doubling of the beneficial effects of biventricular pacing," Wright told heartwire . "CRT devices are in and of themselves expensive and the surgery is expensive, but the benefits of cardiac resynchronization therapy are significant. The cost of cardiac rehabilitation is very small compared with the implantation of a CRT device, yet you get additional benefits in terms of exercise improvement and quality-of-life improvement. We feel that it's a little bit of a cost for lot of an additional benefit."

Juice Is Worth the Squeeze

In an editorial accompanying the published study, Dr Stanley Rubin (Veterans Affair Medical Center, Los Angeles, CA) notes that exercise training is a class 1 recommendation (level of evidence B) for patients with current or prior symptoms of heart failure with reduced systolic function, based largely on evidence showing that training increases exercise duration, intensity, and distance on six-minute-walk tests and also improves quality of life [2]. However, the HF-ACTION study, previously reported by heartwire , showed a structured program did not improve survival or decrease hospital length of stays.

However, Rubin states that the "juice" is likely worth the "squeeze," meaning that the benefits of exercise training are sufficient to justify their effort. In addition, he notes that while hard end points are yet unproven, such as in the "elusive prize of increased survival and decreased hospital stay," improved soft end points, including quality of life and functional capacity, would be welcomed by most patients and physicians.

Rubin adds that while every patient is eligible, exercise is not advised for systolic-dysfunction heart-failure patients with significant aortic stenosis or those with other illnesses that prevent movement. After a physician properly determines a patient's eligibility, training should emphasize aerobic activities, with a small amount of strength training included.

Wright said that based on these findings, health services at his hospital and throughout Liverpool now prescribe exercise rehabilitation for all CRT patients. "If you have a heart attack or bypass surgery, you're then entered into a rehabilitation program," he said. "That hasn't been the case with cardiac resynchronization devices."

References

1. Patwala AY, Woods PR, Sharp L, et al. Maximizing patient benefit from cardiac resynchronization therapy with the addition of structured exercise training. J Am Coll Cardiol 2009; 53:2332-2339.
2. Rubin SA. Remix: Exercise training and cardiac resynchronization therapy in heart failure. J Am Coll Cardiol 2009; 53:2340-2342.

Clinical Context

Study Highlights

• Patients were recruited for study participation from 1 study center. All participants had NYHA class III or IV heart failure and were awaiting CRT. Eligible patients had stable heart failure for at least 1 month and were free of noncardiac physical limitations.
• All patients received CRT with an atriobiventricular pacemaker. They underwent randomization to an exercise therapy or control group at 3 months after CRT.
• The exercise group underwent three 30-minute sessions per week of aerobic activity, all under the supervision of a physician. The work load during exercise was gradually increased to 90% of participants' peak heart rate at baseline. The control group received no special instructions regarding exercise training.
• The main outcomes of the study were results of exercise testing, quality-of-life assessments, echocardiography, and peak muscle strength on knee extension at 6 months after CRT.
• 50 participants entered the study. The mean age was 64.4 years, and 92% of participants were men. Patients had a mode NYHA functional class of III.
• 3 months after CRT (at the time of randomization to exercise therapy or control groups), peak exercise oxygen uptake, exercise duration, and NYHA class function were improved from baseline. Left ventricular ejection fraction and quality of life were also improved.
• The randomized groups were similar with regard to outcomes at 3 months after CRT.
• At 6 months after CRT, improvement in peak exercise oxygen uptake, quality-of-life scores, and NYHA functional class continued to improve in the exercise group.
• Compared with the control group, the exercise group experienced significantly improved outcomes in NYHA functional class, exercise duration, peak exercise oxygen uptake, and quality of life.
• At 6 months, the exercise group had no significant improvement in left ventricular end-diastolic dimension vs usual care, but the mean left ventricular ejection fraction improved in the exercise group vs the control group.
• Leg extension power was similar between groups at 6 months.
• No patient experienced complications from the exercise training.

Clinical Implications

• Among patients with systolic dysfunction heart failure, aerobic exercise improves ventricular remodeling and ejection fraction. It also improves peak exercise oxygen uptake, work capacity, and health-related quality of life.
• In the current study, an exercise therapy program improved peak exercise oxygen uptake, exercise duration, quality-of-life scores, and NYHA functional class among patients who had received CRT for heart failure.

Source : http://cme.medscape.com/viewarticle/704959?src=cmemp