Primecuts – This Week In The Journals

May 2, 2011

By Ian Fagan, MD 

Faculty Peer Reviewed

Is springtime the season for love? Take a look outside—the birds are chirping, the bees are buzzing, the flowers are blooming. There are strangers mingling in the parks, couples out and about holding hands. The energy is palpable and signs of blossoming love are abundant. Even this week’s journals couldn’t avoid matters of the heart.

For instance, the New England Journal of Medicine published an article looking at coronary-artery bypass grafting (CABG) in patients with left ventricular dysfunction. Between 2002 and 2007, roughly 1,200 patients with an ejection fraction less than 35% and known CAD were randomized to medical therapy alone or medical therapy plus CABG. The primary outcome was death from any cause. The researchers found that the primary outcome occurred in 41% of patients in the medical therapy group versus 36% in the CABG group, a non-significant difference. The secondary endpoint was death due to a proven cardiovascular cause. This occurred in 33% of patients in the medical therapy group compared to 28% of patients in the CABG group, a significant difference (p = 0.05). Although the evidence is far from conclusive, this study supports the idea that ischemic heart failure patients may do just as well without that trip to the operating room.

Picking up on the heart failure theme, JAMA published an article this week looking at health literacy and its affects on outcomes in patients with heart failure. In a retrospective cohort study conducted in Colorado, outpatients with heart failure were surveyed by mail. Their health literacy was assessed using established screening questions and was then categorized as low or adequate.  Of the 1,494 responders, 262 (17.5%) had low health literacy. These patients, on average, were older, of lower socioeconomic status, less likely to have a high school education, and had higher rates of comorbid illness. Low health literacy was independently associated with higher mortality (crude  mortality rate of 17.6% versus 6.3% for those with adequate health literacy, with an adjusted hazard ratio of 1.97 (1.3 – 2.97)). This suggests that in a disease like heart failure, which requires significant self-management and self-titration of medications, understanding your patients’ limitations and tailoring your education correspondingly may make all the difference.

This week, the Archives of Internal Medicine examined whether the HIV virus is an independent risk factor for heart failure. In this retrospective cohort study, 8,486 HIV-infected and HIV-uninfected veterans were studied. During the 7.3 years of follow up, 286 incident heart failure events occurred. After adjusting for age and race, the heart failure rate for HIV-infected patients and HIV-uninfected patients were 7.12 and 4.82 per 1000 person-years, respectively. This corresponded to a hazard ratio of 1.81 (1.39 – 2.36). This association remained even after adjusting for more confounders such as prior heart failure and history of alcohol abuse. Furthermore, those HIV-infected patients with an HIV-1 RNA level greater than 500 copies/mL had a greater risk of heart failure than those with less than 500 copies/mL (adjusted hazard ratio of 2.28 (1.57 – 3.32)). Although the mechanism of disease is unclear, it seems as though HIV may truly be a risk factor for the development of heart failure.

Even the gastroenterologists were concerned with the heart this week. A group of researchers from the University of Miami published an article in the American Journal of Gastroenterology looking at whether inflammatory bowel disease (IBD) is associated with an increased incidence of cardiovascular events.  In this longitudinal cohort study, 356 IBD patients and 712 matched controls were monitored for the development of CAD. They found an unadjusted hazard ratio of 2.85 (1.82 – 4.46). Of note, IBD patients had significantly lower rates of traditional CAD risk factors such as hypertension, diabetes, dyslipidemia, and obesity. After adjusting for these factors, the hazard ratio increased to 4.08 (2.49 – 6.70). Researchers believe that the chronic systemic inflammation seen in IBD may be an independent risk factor in the pathogenesis of CAD. Furthermore, some believe that the inflammation may affect the coagulation cascade, which then induces endothelial dysfunction. Their exciting results highlight the need for more basic science research into this area.

On a similar note, the American Journal of Cardiology published an article this week regarding the impact of caffeine ingestion on endothelial function in patients with coronary artery disease. Researchers compared 40 patients with CAD to 40 controls on the basis of brachial artery flow-mediated dilation (FMD). After overnight fasting, discontinuation of all meds for 12 hours, and the absence of caffeine for 48 hours, patients received 200mg caffeine capsules or placebo.  FMD was then measured one hour after ingestion. At baseline, FMD was significantly lower in patients with CAD compared to controls (5.6% versus 8.4%), and acute caffeine ingestion significantly increased FMD in both CAD patients (14.6%) and controls (18.6%). Although the jury is still out, this study shows that caffeine ingestion actually improves endothelial function. Interestingly, caffeine did not significantly impact the resting heart rate in either group. While new love this spring might give you a hummingbird heartbeat, it seems that caffeine officially does not.

Ian Fagan is a first year resident at NYU Langone Medical Center

Peer reviewed by Ishmeal Bradley, Section Editor, Clinical Correlations

Image courtesy of Wikimedia Commons.

References:

1. Velazquez EJ, Lee KL, Deja MA, et al. Coronary-artery bypass surgery in patients with left ventricular dysfunction. N Engl J Med 2011; 364: 1607 – 1616 http://www.nejm.org/doi/full/10.1056/NEJMoa1100356

2. Peterson PN, Shetterly SM, Clarke CL, et al. Health literacy and outcomes among patients with heart failure. JAMA. 2011;305(16):1695-1701 http://jama.ama-assn.org/content/305/16/1695

 3. Butt AA, Chang CC, Kuller L, et al. Risk of heart failure with human immunodeficiency virus in the absence of prior diagnosis of coronary heart disease. Arch Intern Med. 2011;171(8):737-743 http://archinte.ama-assn.org/cgi/content/short/171/8/737

 4. Yarur AJ, Deshpande AR, Pechman DM, et al. Inflammatory bowel disease is associated with an increased incidence of cardiovascular events. Am J Gastroenterol 2011; 106:741–747. http://www.nature.com/ajg/journal/v106/n4/full/ajg201163a.html

 5. Shechter M, Shalmon G, Scheinowitz M, et al. Impact of acute caffeine ingestion on endothelial function in subjects with and without coronary artery disease. Am J Cardiol 2011;107:1255–1261) http://www.ajconline.org/article/S0002-9149%2811%2900125-1

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