Title: Stent Graft Versus Balloon Angioplasty for Failing Dialysis-Access Grafts
Topic: Interventional Cardiology
Date Posted: 2/10/2010 5:00:00 PM
Author(s): Haskal ZV, Trerotola S, Dolmatch B, et al.
Citation: N Engl J Med 2010;362:494-503.
Clinical Trial: yes
Study Question: What is the benefit of using polytetrafluoroethylene (PTFE) stent graft compared with balloon angioplasty only for treating patients with venous anastomosis stenosis associated with hemodialysis grafts?
Methods: The authors randomized 190 patients who had venous anastomosis stenosis to undergo angioplasty only versus treatment with a PTFE stent graft. Primary endpoint was patency of the access site at 6 months.
Results: Randomization to stent graft was associated with better patency of the treatment site (51% vs. 23%, p < 0.001) and patency of the access circuit (38% vs. 20%, p = 0.008). Binary restenosis was much greater with angioplasty (78% vs. 28%, p < 0.001). The stent graft arm was more likely to be free of need for subsequent intervention at 6 months.
Conclusions: Stent grafting is superior to balloon angioplasty only for the treatment of venous anastomosis stenosis associated with hemodialysis grafts.
Perspective: Dialysis access using prosthetic grafts is inferior to autogenous arterio-venous fistulas due to the high incidence of graft failure. Venous anastomosis stenosis is a recalcitrant problem and is responsible for a large proportion of graft failures. Balloon angioplasty has been traditionally used for these lesions, although it has been plagued with a high restenosis rate. This trial has established stent grafts as the current standard of care for these lesions even though the recurrence rate with stent grafts still remains unacceptably high. Further research is needed to identify effective therapeutic strategies that can be used to further reduce restenosis in these lesions. Hitinder S. Gurm, M.B.B.S., F.A.C.C.
Title: Physical Activity and Physiological Cardiac Remodelling in a Community Setting: The Multi-Ethnic Study of Atherosclerosis (MESA)
Topic: Noninvasive Cardiology
Date Posted: 2/9/2010
Author(s): Turkbey EB, Jorgensen NW, Johnson WC, et al.
Citation: Heart 2010;96:42-48.
Clinical Trial: No
Study Question: Is there an association between physical activity and left ventricular (LV) structure and function in the general population in a community setting?
Methods: Subjects included 4,992 multiethnic participants (age 45-84 years; 52% women) free of clinically apparent cardiovascular disease enrolled in a cross-sectional population-based study of subclinical atherosclerosis (The Multi-Ethnic Study of Atherosclerosis [MESA]). LV mass, volumes, and function were assessed by cardiac magnetic resonance imaging. Physical activity, defined as intentional exercise and total moderate and vigorous physical activity, was assessed by a standard semi-quantitative questionnaire.
Results: LV mass and end-diastolic volume were positively associated with physical activity (1.4 g/m2 [women] and 3.1 g/m2 [men] greater LV mass in the highest category of intentional exercise compared with individuals reporting no intentional exercise; p = 0.05 and p < 0.001, respectively). Relationships were nonlinear, with stronger positive associations at lower levels of physical activity (test for nonlinearity; p = 0.02 and p = 0.03, respectively). Cardiac output and ejection fraction were unchanged with increased physical activity levels. Resting heart rate was lower in women and men with higher physical activity levels (22.6 bpm lower resting heart rate in the highest category of intentional exercise compared with individuals reporting no intentional exercise; p < 0.001).
Conclusions: In a community-based population free of clinically apparent cardiovascular disease, higher physical activity levels were associated with proportionally greater LV mass and end-diastolic volume and lower resting heart rate.
Perspective: Predominantly studied in high-performance athletes, the ‘athlete’s heart’ has adapted to intense physical training with increased LV end-diastolic diameter, increased myocardial mass, and decreased resting heart rate. This study reveals that, among active individuals not trained as elite athletes, higher levels of physical activity are associated with cardiac changes similar to those seen with more intense training. It is important to note that increased LV mass, associated with increased cardiovascular risk among patients with hypertension, appears benign (or even beneficial) when it is acquired with physical activity. The known inverse relationship between moderate to vigorous physical activity and risk for premature death and other cardiovascular diseases occurs despite what is shown in this study. An increased LV mass, in other scenarios, would raise concern. David S. Bach, M.D., F.A.C.C.
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