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"The research team chose to test fish oil in patients who were prone to arrhythmias because any benefits probably would be obvious and apply to a lot of people."

On Tue, 26 Jul 2005 03:55:01 GMT, Dan wrote in misc.kids.pregnancy,sci.med,sci.med.nutrition : USA TODAY Fish oil supplements found to set off irregular heartbeats By Steve Sternberg, USA TODAY Fish oil supplements could trigger potentially deadly heart rhythms in people whose hearts already beat dangerously out of sync, doctors report today. The finding, from a study of 200 patients with implanted defibrillators that shock the heart back to a normal rhythm, surprised researchers who expected to find that fish oil guards against rhythm abnormalities in patients who need protection most. The heart gets its pumping power from cells that fire in sequence as electrical charges race from one cell to another. Rhythm disturbances occur when these circuits misfire, causing the heart to beat out of sync and lose its pumping power. The result can be rest caused by a kind of electrical storm rather than the clogged arteries that cause "standard" heart attacks. Four previous studies have shown that fish oils cut the risk of bane heart rhythm problems, called arrhythmias, in patients who had had standard heart attacks. The research team chose to test fish oil in patients who were prone to arrhythmias because any benefits probably would be obvious and apply to a lot of people. About 150,000 people each year receive implanted defibrillators. "Our initial thought was that this was a great population in which to show that fish oil is anti-arrhythmic," says study leader Merritt Raitt of the Portland VA Medical Center. His team's report appears in today's Journal of the American Medical buttociation. The research was carried out at six major medical centers from 1999 to 2003. Half of the patients were given fish oil. The rest were given olive oil, a placebo. Researchers found that 65% of the patients who took fish oil supplements developed rhythm disturbances over the next six months, compared with 36% of those in the placebo group. Nearly two-thirds of subjects taking fish oil who had a type of rapid heartbeat known as tachycardia experienced episodes, compared with 37% of those taking placebo. "This is a really interesting study," says Alice Lichtenstein, a Tufts University cardiovascular nutritionist. "It's telling us that just popping a pill doesn't always lead to the expected result. It may seem like a quick and easy way of treating a problem, but usually things are a lot more complex." Dietary omega-3 fatty acids, the active ingredients in fish oil, repeatedly have been linked to a decreased heart disease risk because of their beneficial properties, Lichtenstein says. "They're anti-inflammatory, they minimize clot formation, they may have a mild antihypertensive effect, and, if people are eating fish, they're not eating steak," she says. "That decreases their fat intake." Raitt says he can only speculate why fish oil hurt rather than helped. But he says other drugs shown to prevent rhythm disturbances also can cause them. "Drugs that affect rhythms are double-edged swords," he says. "The people they're most likely to hurt are the ones with the sickest hearts, with recurrent arrhythmias, the ones we had in our study." === JAMA - Journal of the American Medical buttociation Vol. 293 No. 23, June 15, 2005 Original Contribution Fish Oil Supplementation and Risk of Ventricular Tachycardia and Ventricular Fibrillation in Patients With Implantable Defibrillators A Randomized Controlled Trial Merritt H. Raitt, MD; William E. Connor, MD; Cynthia Morris, PhD, MPH; Jack Kron, MD; Blair Halperin, MD; Sumeet S. Chugh, MD; James McClelland, MD; James Cook, MD; Karen MacMurdy, MD; Robert Swenson, MD; Sonja L. Connor; Glenn Gerhard, MD; Dale F. Kraemer, PhD; Daniel Oseran, MD; Christy Marchant, RN, MBA; David Calhoun, RN; Reed Shnider, MD; John McAnulty, MD JAMA. 2005;293:2884-2891. Context Clinical studies of omega-3 polyunsaturated fatty acids (PUFAs) have shown a reduction in sudden cardiac rest, suggesting that omega-3 PUFAs may have antiarrhythmic effects. Objective To determine whether omega-3 PUFAs have beneficial antiarrhythmic effects in patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Design and Setting Randomized, double-blind, placebo-controlled trial performed at 6 US medical centers with enrollment from February 1999 until January 2003. Patients Two hundred patients with an implantable cardioverter defibrillator (ICD) and a recent episode of sustained VT or VF. Intervention Patients were randomly buttigned to receive fish oil, 1.8 g-d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days (range, 20-828 days). Main Outcome Measures Time to first episode of ICD treatment for VT-VF, changes in red blood cell concentrations of omega-3 PUFAs, frequency of recurrent VT-VF events, and predetermined subgroup analyses. Results Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 6, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT-VF compared with 36% (5%), 41% (5%), and 59% (5%) for patients randomized to receive placebo (P = .19). In the subset of 133 patients whose qualifying arrhythmia was VT, 61% (SE, 6%), 66% (6%), and 79% (6%) of patients in the fish oil group had VT-VF at 6, 12, and 24 months compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007). Recurrent VT-VF events Conclusion Among patients with a recent episode of sustained ventricular arrhythmia and an ICD, fish oil supplementation does not reduce the risk of VT-VF and may be proarrhythmic in some patients. === X'Posted to: misc.kids.pregnancy,sci.med,sci.med.nutrition