Even 10 Minutes of Exercise Beneficial After ICD Implantation

Small increases in daily physical activity are associated with a boost in 1-year survival in patients with heart failure and coronary disease who received an implantable cardioverter defibrillator (ICD), new research suggests.

“Our study looked at how much exercise was necessary for a better outcome in patients with prior ICD implantation and, for every 10 minutes of exercise, we saw a 1% reduction in the likelihood of death or hospitalization, which is a pretty profound impact on outcome for just a small amount of additional physical activity per day,” lead author Brett Atwater, MD, told theheart.org | Medscape Cardiology.

“These improvements were achieved outside of a formal cardiac rehabilitation program, suggesting that the benefits of increased physical activity obtained in cardiac rehabilitation programs may also be achievable at home,” he said.

Cardiac rehabilitation (CR) programs have been shown to improve short- and long-term outcomes in patients with heart failure (HF) but continue to be underutilized, especially by women, the elderly, and minorities. Home based-CR could help overcome this limitation but the science behind it is relatively new, noted Atwater, director of electrophysiology and electrophysiology research, Inova Heart and Vascular Institute, Fairfax, Virginia.

As reported in Circulation Cardiovascular Quality and Outcomes, the study involved 41,731 Medicare beneficiaries (mean age, 73.5 years) who received an ICD from 2014 to 2016.

ICD heart rate and activity sensor measurements were used to establish a personalized physical activity (PA) threshold for each patient in the first 3 weeks after ICD implantation. Thereafter, the ICD logged PA when the personalized PA threshold was exceeded. The mean baseline PA level was 128.9 minutes/day.

At 3 years’ follow-up, one-quarter of the patients had died and half had been hospitalized for HF. Of the total population, only 3.2% participated in CR.

Compared with nonparticipants, CR participants were more likely to be White (91.0% vs 87.3%), male (75.5% vs 72.2%), and to have diabetes (48.8% vs 44.1%), ischemic heart disease (91.4% vs 82.1%), or congestive heart failure (90.4% vs 83.4%).

CR participants attended a median of 24 sessions, during which time daily PA increased by a mean of 9.7 minutes per day. During the same time, PA decreased by a mean of 1.0 minute per day in non-CR participants (P < .001).

PA levels remained “relatively constant” for the first 36 months of follow-up among CR participants before showing a steep decline, whereas levels gradually declined throughout follow-up among nonparticipants, with a median annual change of –4.5 min/day.

In adjusted analysis, every 10 minutes of increased daily PA was associated with a 1.1% reduced risk for death (hazard ratio [HR], 0.989; 95% CI, 0.979 – 0.996) and a 1% reduced risk for HF hospitalization (HR, 0.99; 95% CI, 0.986 – 0.995) at 1-year follow-up (P < .001).

After propensity score was used to match CR participants with nonparticipants by demographic characteristics, comorbidities, and baseline PA level, CR participants had a significantly lower risk for death at 1 year (HR, 0.76; 95% CI, 0.69 – 0.85). This difference in risk remained at 2- and 3-year follow-ups.

However, when the researchers further adjusted for change in PA during CR or the same time period after device implantation, no differences in mortality were found between CR participants and nonparticipants at 1 year (HR, 1.00; 95% CI, 0.82 – 1.21) or at 2 or 3 years.

The risk for HF hospitalization did not differ between the two groups in either propensity-score model.

Unlike wearable devices, implanted devices “don’t give that type of feedback to patients regarding PA levels — only to providers — and it will be interesting to discover whether providing feedback to patients can motivate them to do more physical activity,” Atwater commented.

The team is currently enrolling patients in a follow-up trial, in which patients will be given feedback from their ICD “to move these data from an interesting observation to something that can drive outcomes,” he said.

Commenting for theheart.org | Medscape Cardiology, Melissa Tracy, MD, Rush University Medical Center, Chicago, said the study reiterates the “profound” underutilization of CR.

“Only about 3% of patients who should have qualified for cardiac rehabilitation actually attended, which is startling considering that it has class 1A level of evidence supporting its use,” she said.

Tracy, who is also a member of the American College of Cardiology’s Prevention of Cardiovascular Disease Section Leadership Council, described the study as “another notch in the belt of positive outcomes supporting the need for cardiac rehabilitation” and emphasizing the importance of a home-based alternative.

“One of the reasons women, minorities, and older patients don’t go to cardiac rehabilitation is they have to get there, rely on someone to drive them, or they have other responsibilities — especially women, who are often primary caretakers of others,” she said. “For women and men, the pressure to get back to work and support their families means they don’t have the luxury to go to cardiac rehabilitation.”

Tracy noted that home-based CR is covered by CMS until the end of 2021. “An important take-home is for providers and patients to understand that they do have a home-based option,” she stated.

Limitations of the study are that only 24% of patients were women, only 6% were Black, and the results might not be generalizable to patients younger than 65 years, note Atwater and colleagues. Also, previous implantation might have protected the cohort from experiencing arrhythmic death, and it remains unclear if similar results would be obtained in patients without a previous ICD.

This research was funded through the unrestricted Abbott Medical-Duke Health Strategic Alliance Research Grant. Atwater receives significant research support from Boston Scientific and Abbott Medical, and modest honoraria from Abbott Medical, Medtronic, and Biotronik. Coauthor disclosures are listed in the paper. Tracy has created virtual and on-demand cardiac rehabilitation and cardiac prevention programs with Virtual Health Partners (VHP) and owns the intellectual property and consults with VHP but receives no monetary compensation.

Circ Cardiovasc Qual Outcomes. Published online July 21, 2021. Abstract

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