Circulation: Clinical Summaries
Original Research Put Into Perspective for the Practicing Clinician
- Cardiorespiratory Fitness and Risk of Incident Atrial Fibrillation: Results From the Henry Ford Exercise Testing (FIT) Project
- Prospective Randomized Trial of Moderately Strenuous Aerobic Exercise After an Implantable Cardioverter Defibrillator
- Atrial Fibrillation and Risk of ST-Segment–Elevation Versus Non–ST-Segment–Elevation Myocardial Infarction: The Atherosclerosis Risk in Communities (ARIC) Study
- High-Sensitivity Cardiac Troponin I and B-Type Natriuretic Peptide as Predictors of Vascular Events in Primary Prevention: Impact of Statin Therapy
- Fibroblast Growth Factor 21 Prevents Atherosclerosis by Suppression of Hepatic Sterol Regulatory Element-Binding Protein-2 and Induction of Adiponectin in Mice
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Cardiorespiratory Fitness and Risk of Incident Atrial Fibrillation: Results From the Henry Ford Exercise Testing (FIT) Project
Atrial fibrillation (AF) is an increasingly prevalent condition. Fitness has been shown to be associated with a lower risk of a number of cardiovascular diseases. However, few studies have assessed whether higher fitness is associated with a lower risk of AF. Using a diverse population of >64 000 patients, we establish that fitness has a strong, inverse association with incident AF. Fitness was even more inversely associated with AF among obese patients. This study establishes fitness as an independent risk factor of AF and further raises the question of whether improving one’s fitness might help prevent AF, an important question for subsequent research. See p 1827.
Prospective Randomized Trial of Moderately Strenuous Aerobic Exercise After an Implantable Cardioverter Defibrillator
Aerobic exercise is often avoided after receipt of an implantable cardioverter-defibrillator (ICD) because of fears that exercise may provoke acute arrhythmias and ICD shocks. We prospectively evaluated the effects of a home-based aerobic exercise training and maintenance program on aerobic performance, ICD shocks, and hospitalizations exclusively in ICD recipients. Aerobic conditioning consisted of moderate-to-strenuous aerobic exercise (home walking 5 h/wk × 8 weeks at 60% to 80% of heart rate reserve), followed by aerobic maintenance (home walking for 150 min/wk × 16 weeks at 80% of heart rate reserve). Exercise was found to be safe without causing any ICD shocks or hospitalizations and effective in improving peak aerobic performance. Aerobic exercise was monitored using HR monitors, telephone coaching by a nurse, pedometers, exercise logs, and the Borg scale. Clinical guidelines need to be updated to include exercise testing parameters and prescriptions for patients with ICDs. Findings should help dispel concerns by providers and patients alike about the benefits and safety of moderately strenuous exercise after an ICD. Having an ICD should not relegate individuals to lifelong sedentary activity because of fear of recurrent arrhythmias or ICD shocks. See p 1835.
Atrial Fibrillation and Risk of ST-Segment–Elevation Versus Non–ST-Segment–Elevation Myocardial Infarction: The Atherosclerosis Risk in Communities (ARIC) Study
It has recently been reported that atrial fibrillation (AF) is associated with an increased risk of myocardial infarction (MI). However, the mechanism underlying this association is currently unknown. Further study of the relationship of AF with the type of MI (ST-segment–elevation MI versus non–ST-segment–elevation MI) might shed light on the potential mechanisms. In this analysis from the Atherosclerosis Risk in Communities (ARIC) study, we showed that AF is associated with an increased risk of incident MI, confirming recent reports. However, the association between AF and MI was limited to non–ST-segment–elevation MI, suggesting that factors leading to partial occlusion of the coronary arteries or increased oxygen demand, but not total coronary occlusion via direct thromboembolism, are more likely to explain the observed association between AF and MI. See p 1843.
High-Sensitivity Cardiac Troponin I and B-Type Natriuretic Peptide as Predictors of Vascular Events in Primary Prevention: Impact of Statin Therapy
Circulating concentrations of cardiac troponin and B-type natriuretic peptide (BNP) as markers of myocardial necrosis and strain, respectively, have shown strong, consistent associations with adverse cardiovascular outcomes, including myocardial infarction, stroke, and cardiovascular death. Little is known about therapies that might improve outcomes for patients with cardiac troponin or BNP concentrations that place them at increased cardiovascular risk. In this study, we sought to determine whether statin therapy might be particularly effective in patients with higher concentrations of either cardiac biomarker. We measured cardiac troponin I with a novel, high-sensitivity assay (hsTnI) and BNP in 12 956 men and women enrolled in the Justification for the Use of Statins in Prevention: An Intervention Trial Evaluating Rosuvastatin (JUPITER) trial, a randomized, double-blind, placebo-controlled trial of rosuvastatin 20 mg/d in patients without pre-existing cardiovascular disease. Patients with either hsTnI or BNP concentrations in the highest tertile were at approximately double the risk of a first major vascular event, even after adjustment for a wide variety of cardiovascular risk factors. This relationship was consistent across a broad array of high- and low-risk subgroups and was also seen for all-cause mortality. The effects of rosuvastatin were substantial and were consistent across baseline hsTnI or BNP concentrations, with a 40% to 50% reduction in the risk of a major vascular event for all participants. Because hsTnI appeared to identify individuals at high absolute risk of vascular events, rosuvastatin use in participants with higher hsTnI concentrations led to a substantial reduction in the absolute risk of these clinically important events. See p 1851.
Fibroblast Growth Factor 21 Prevents Atherosclerosis by Suppression of Hepatic Sterol Regulatory Element-Binding Protein-2 and Induction of Adiponectin in Mice
Atherosclerosis is a chronic inflammatory disease with many risk factors, including obesity, insulin resistance, diabetes mellitus, and dyslipidemia. Therefore, the therapeutic interventions targeting a single risk factor (eg, the use of statins to decrease hypercholesterolemia) are often insufficient to block the progression of atherosclerotic disease. In this study, we demonstrated that the liver-secreted hormone fibroblast growth factor (FGF) 21 potently alleviates atherosclerotic plaque formation and decreases premature death in apolipoprotein E−/− mice via several mechanisms. First, FGF21 induces the production of adiponectin, which in turn acts on the blood vessels directly to inhibit neointima formation and macrophage inflammation. Second, FGF21 exerts its autocrine actions in the liver to suppress lipid biosynthesis, thereby reducing hypertriglyceridemia and hypercholesterolemia. Consistent with our animal findings, chronic administration of an FGF21 analog in type 2 diabetic patients with obesity has been shown to reduce several cardiovascular risk factors, including insulin resistance, dyslipidemia, and hypoadiponectinemia. Notably, FGF21 is a downstream effector for both the nuclear receptors peroxisome proliferator-activated receptor (PPAR) α and γ, the agonists of which are effective for treatment of both metabolic and vascular diseases. Therefore, our results raise the possibility that FGF21 or its analogs may represent a promising cure for atherosclerotic diseases via its multiple actions in adipose tissue, blood vessels, and liver. Furthermore, our findings suggest that elevated circulating FGF21 levels in patients with atherosclerosis and cardiovascular disorders, which has been observed in both cross-sectional and prospective studies on several ethnic groups, may represent the body’s compensatory responses to defend these diseases. See p 1861.
- © 2015 American Heart Association, Inc.
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