Featured topics in the current and recent issues of the JACC family of journals

‘Profound’ Overall Positive Effects of Cardiac Rehab

Exercise-based cardiac rehab reduces cardiovascular mortality while providing important data showing reductions in hospital admissions and improvement in quality of life, confirms a study published Jan. 4 in JACC.

In this systematic review, researchers examined 63 studies with 14,486 patients with a follow-up of 12 months. The exercise-based cardiac rehab programs were usually delivered in a supervised hospital- or center-based setting, either exclusively or in combination with home exercise sessions.

The researchers found a reduction in cardiovascular mortality and hospital admission with exercise-based cardiac rehab compared with controls. There was no difference in total mortality or the risk of fatal or non-fatal myocardial infarction (MI), coronary artery bypass grafting, or percutaneous coronary intervention. These outcomes were seen across trials regardless of patient case mix, the nature of the cardiac rehab program, and study characteristics.

A total of 20 studies assessed health-related quality of life and 13 reported a higher level of quality of life in one or more subscales following exercise-based cardiac rehab compared with controls; in five studies, there was a higher level of quality of life in half or more of the subscales. The researchers also found that exercise-based cardiac rehab can be a cost-effective use of health care resources.

However, the authors write that “despite the observed improvements in cardiovascular mortality, in a context of contemporary coronary heart disease medical treatments, the opportunity for additional gains in overall mortality with exercise-based cardiac rehab may be small.” They add that their findings suggest “that although cardiac rehab does not improve coronary vascular function or integrity, it does confer improved survival in patients post-MI.”

In a related editorial comment, Carl J. Lavie, MD, FACC, and colleagues write that these findings “[suggest] quite profound overall positive effects of cardiac rehab programs, even if the impact on total mortality has lessened.”

They add that there is considerable evidence that the current model for cardiac rehab delivery appears to be neither financially viable nor sustainable. Additionally, despite the benefits of cardiac rehab, only a fraction of eligible patients are currently referred to, participate in, and complete cardiac rehab programs. “Moving forward, efforts must be made to increase cardiac rehab program participation, which can be accomplished by improving processes and flexibility in the current model, creating and implementing alternative cardiac rehab approaches, and capitalizing on recent technological advances.”

Automatic referral to cardiac rehab has been adopted for many candidates, but many patients do not attend. Endorsement from health care providers and early initiation is important. Future models for cardiac rehabilitation should look beyond the current hospital-based programs and include home-, internet-, and community-based programs.

Lavie and colleagues conclude that alternative secondary prevention models may help to reach a larger patient population over an extended period of time. With changes, cardiac rehab “may transform its impact from the individual to the population level and re-establish, or even improve upon, the previously reported overall mortality benefits of this intervention.”

Anderson L, Oldridge N, Thompson DR, et al. JACC. 2015;doi:10.1016/j.jacc.2015.10.044.

Obesity, Exercise, Obstructive Sleep Apnea: Are These Modifiable Risk Factors for AF?

The three pillars of atrial fibrillation (AFib) management have long included anticoagulation, rhythm control, and rate control. Now, a review paper published Dec. 21 in JACC examines the evidence supporting a fourth pillar. Aggressive risk factor modification—especially weight loss—may help in preventing AF as well as manage and reduce complications in patients with AF.

Over the last 5 years, studies have established the close relationship between obesity and AF risk. Body mass index (BMI) is included in prediction models for new-onset AF, and other adiposity measures have also been associated with increased AF risk. Increased BMI is also associated with increased left atrial size, which is associated with higher risk of AF. Additionally, pericardial fat in obese individuals is related to the presence, severity, and post-ablation recurrence of AF, independent of BMI. Finally, obesity is a state of chronic systemic inflammation, which has a key role in the occurrence of AF.

Recent studies have shown that weight reduction has an important role in AF management. Exercise paired with a low-calorie diet has shown to reduce the frequency of AF episodes, reduce the duration of AF, and lower the severity of symptoms. After ablation procedures, weight loss has demonstrated to reduce the recurrence of AF.

Light to moderate exercise is associated with a lower incidence in AF compared with those who do not exercise at all. However, this benefit may not extend to high-intensity exercise. In fact, studies have shown a link between endurance exercise and increased AF risk. Higher cardiorespiratory fitness is also associated with a greater arrhythmia-free survival both with and without rhythm-control strategies. The authors write that, given all of the cardiovascular benefits of routine exercise, it is logical to recommend regular, moderate exercise as part of AF prevention and management.

Approximately half of AF patients have obstructive sleep apnea (OSA) and AF has a greater association with OSA than BMI, hypertension, and diabetes. Treatment of OSA is an important component of AF management. According to the authors, routine screening for OSA prior to the use of a rhythm control strategy may be warranted.

The authors conclude that there is growing evidence to support aggressive risk factor modification in the context of an AF risk factor management plan. There is evidence to support a comprehensive strategy of weight loss, exercise and fitness, screening for OSA, and treatment of traditional modifiable cardiovascular disease risk factors. However, further research is needed before making specific recommendations and guidelines on appropriate weight loss and fitness targets.

Miller JD, Aronis KN, Chrispin J, et al. JACC. 2015;doi:0.1016/j.jacc.2015.10.047.

Depression, Subclinical CVD, and the Protective Effects of Physical Activity

Exercise may prevent the cardiovascular risks associated with depression, according to a research letter published Jan. 11 in JACC.

Physiological stress can trigger many physiologic responses. Up to 20% of individuals hospitalized for myocardial infarction report symptoms of depression, and patients with cardiovascular disease (CVD) are three times more likely to develop depression compared with the general population. Depression can also lead to worse cardiovascular and non-cardiovascular outcomes.

To determine the relationship between exercise and the cardiovascular risks of depression, researchers evaluated the effects of regular physical activity in 965 subjects who were free of heart disease, cerebrovascular or peripheral arterial disease, and without a prior diagnosis of an affective, psychotic, and/or anxiety disorder. Subjects completed a questionnaire assessing depressive symptoms over the previous 2 weeks. Researchers determined if the subjects met the 2008 Physical Activity Guideline for Americans, which recommends 150 or 75 minutes per week of moderate- or vigorous-intensity physical activity, respectively, or an equivalent combination of the two. Oxidative stress and vascular function were assessed.

Higher rates of depressive symptoms correlated with a higher augmentation index and C-reactive protein (CRP) levels, as well as lower subendocardial viability ratio (SEVR) and total glutathione levels. Subjects with worsening depressive symptoms had progressively higher augmentation index and CRP, as well as lower SEVR and glutathione.

Researchers found significant interaction effects between physical activity and depressive symptoms for augmentation index, CRP, and SEVR. Vascular stiffening and systemic inflammation, which accompany worsening depressive symptoms, were more pronounced in sedentary subjects. These relationships were diminished in subjects who regularly participated in moderate to vigorous physical activity.

According to the authors, while physical exercise appears to prevent the adverse cardiovascular consequences of depression, these findings need to be confirmed by a randomized trial.

Mheid IA, Held E, Uphoff I, et al. JACC. 2015;doi:10.1016/j.jacc.2015.10.057.

Excess Weight in Early Adulthood May Increase Risk of Cardiac Death

Being overweight or obese throughout adulthood—especially during early adulthood—may lead to an increased risk of sudden cardiac death, according to a study published Nov. 25 in JACC: Clinical Electrophysiology.

Researchers led by Stephanie Chiuve, ScD, an assistant professor of medicine at Harvard Medical School, analyzed data from the Nurses’ Health study, following 72,484 healthy women from 1980 to 2012. Over the study period, researchers documented 445 cases of sudden cardiac death, 1,286 cases of fatal coronary heart disease, and 2,272 non-fatal myocardial infarction (MI). Results showed women who were overweight (body mass index [BMI] 25-30) and obese (BMI 30 or greater) were 1.5 and 2 times more likely, respectively, to experience sudden cardiac death over the next 2 years compared with women that have a healthy weight (BMI 21-23).

Further, women who were overweight or obese at the start of the study, or obese at age 18, had an elevated risk of sudden cardiac death over the entire course of the study. Weight gain in early-to-mid adulthood was associated with a greater risk of sudden cardiac death at age 18, regardless of BMI. Women with a higher BMI were also at a greater risk of fatal coronary heart disease and non-fatal MI.

According to the researchers, their results showed that the risks from excess weight or weight gain in early adulthood are not completely erased by weight loss later in life. Additionally, nearly three-quarters of patients who suffer from sudden cardiac death are not considered high-risk by current guidelines. Moving forward, they explain that broader prevention strategies are needed to reduce the burden of sudden cardiac death.

“This study adds to a growing body of evidence that the adverse effects of obesity on cardiac rhythm, in this case, sudden death risk, begin in early adulthood,” says David J. Wilber, MD, FACC, editor-in-chief of JACC: Clinical Electrophysiology. “It underscores the need for earlier identification and treatment of high-risk individuals.”

Chiuve SE, Sun Q, Sandhu RK, et al. JACCCEP. 2015;doi:10.1016/ j.jacep.2015.07.011.

Study Explores NT-proBNP for Diagnosis in Renal Failure

Amino-terminal pro-B type natriuretic peptide (NT-proBNP) levels may be used to diagnose acute decompensated heart failure (HF) in patients with renal function, according to a study published Dec. 7 in JACC: Heart Failure.

In a systematic review and meta-analysis, Jennifer A. Shaub, MD, from Yale University School of Medicine, and colleagues examined five studies on diagnostic performance and 17 studies on the prognostic ability of NT-proBNP.

They found that for diagnosing acute decompensated HF, the cutpoints in patients with an estimated glomerular filtration rate (eGFR) of < 60 ml/min/1.73 m2 were roughly two-fold higher than the cutpoints in patients with an eGFR of > 60 ml/min/1.73 m2. The specificity and sensitivity were often slightly lower in patients with an eGFR of < 60 compared with patients with an eGFR of > 60. The unadjusted pooled relative risk was 3.01 (95% CI: 2.53 to 3.58) when comparing patients with preserved renal function and elevated NT-proBNP to patients with preserved renal function and normal NT-proBNP.

In addition, the pooled risk ratio for patients with renal dysfunction was 3.25 (95% CI: 2.45 to 4.30), although there was a higher event rate (20.9%) than patients with preserved renal function (11.9%). The pooled risk ratios between patients with preserved and diminished renal function were not different (p = 0.652). In the studies that provided adjusted estimates for the association between NT-proBNP and mortality, the pooled risk ratios for patients with preserved and diminished renal function were similar, and there was no significant difference between the two groups (p = 0.141).

According to the authors, the study’s findings demonstrate that NT-proBNP is useful for diagnosis of acute decompensated HF or prognosis in patients with renal dysfunction, even though these patients have higher plasma levels of NT-proBNP. As the cutpoints varied in the included studies, moving forward, the researchers encourage that future studies are aimed at patients with renal dysfunction to help identify more precise cutpoints.

“We have been concerned for some time as to whether the natriuretic peptide levels portray the same prognostic information in acute HF patients with renal dysfunction,” says Christopher O’Connor, MD, FACC, editor-in-chief of JACC: Heart Failure. “This report by Shaub, et al. highlights the significant value of NT-proBNP in acute decompensated HF patients regardless of renal function. This study broadens our understanding of risk and hopefully will lead to improved outcomes for our patients.”

Schaub JA, Coca SG, Moledina DG, et al. JCHF. 2015;3(12):977-98.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Stress

Keywords: CardioSource WorldNews, Atrial Fibrillation, Death, Sudden, Cardiac, Depression, Electrophysiology, Heart Failure, Myocardial Infarction, Natriuretic Peptide, Brain, Obesity, Overweight, Peptide Fragments, Quality of Life, Risk Factors, Stress, Physiological, Weight Loss

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