Supplemental vitamin E linked to heart failure in large study: effect appears specific to CHF.
This startling finding came from the continuation phase of a randomized, placebo-controlled trial that involved nearly 4,000 patients at high risk for cardiovascular events.
A daily vitamin E supplement has not been shown to provide any medical benefit, but some people believe that it's reasonable to use it anyway because it has no adverse effects. "Now you can't say there isn't a downside," Dr. Salim Yusuf commented at the annual congress of the European Society of Cardiology. Dr. Yusuf, director of the division of cardiology at McMaster University in Hamilton, Ont., led the Heart Outcomes Prevention Evaluation (HOPE) study, which produced the finding.
"The link between vitamin E and heart failure is important. We were not sure it was a real association at the end of the main HOPE study, but the continuation phase made the numbers larger and much more statistically significant. You start to believe it because it involved the hard end point of hospitalizations for heart failure," he said.
The HOPE study involved 9,541 patients with cardiovascular disease or diabetes plus another cardiovascular risk factor. The study tested whether ramipril, an ACE inhibitor, and vitamin E could improve patient outcomes. Results of the initial phase of the study showed that ramipril was beneficial but vitamin E was not (New Engl. J. Med., 342:145-60, 2000).
From the original patient population, 6,786 agreed to remain in a continuation phase of the HOPE study at 174 of the participating centers. All patients went on ramipril therapy, but a subgroup of 3,994 agreed to ongoing randomization to either a daily supplement of 400 IU vitamin E or placebo. These patients were followed for another 2.6 years, producing a total duration of follow-up for the first HOPE study and the continuation phase of 7.1 years.
In the initial HOPE study, the incidence of all heart failure events was 13.5% among patients who took vitamin E and 12.1% among those who took placebo, a difference of borderline statistical significance. The incidence of hospitalizations for heart failure was 5.0% among those who used vitamin E and 4.1% among those who did not, a difference that again had borderline statistical significance.
But the results from the continuation phase, when combined with the original results, show more sharply defined differences, reported Dr. Eva Lohn, a professor of cardiology at McMaster. Heart failure events occurred in 14.7% of those using vitamin E and 12.6% of those on placebo. Hospitalizations for heart failure occurred in 5.8% of patients who used vitamin E and 4.2% of those who did not. For both measures, the difference between the vitamin E and placebo groups was highly statistically significant. The results also showed that vitamin E supplementation raised the risk of heart failure and hospitalizations uniformly throughout the 7 years of treatment.
"Vitamin E should drop dead," commented Dr. Lars Ryden, a professor of cardiology at the Karolinska Institute in Stockholm.
The means by which vitamin E exerts this effect are unknown. The effect appears to be specific to heart failure; patients taking vitamin E did not have an increased risk of other cardiovascular events or death, compared with patients on placebo. One possible explanation is that vitamin E acts as a pro-oxidant in the myocardium, and adversely affects left ventricular function by interfering with excitation-contraction coupling, said Dr. Thomas Munzel, a cardiologist at the University Hospital in Hamburg (Germany).
BY MITCHEL L. ZOLER Philadelphia Bureau
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|Title Annotation:||Clinical Rounds|
|Author:||Zoler, Mitchel L.|
|Publication:||OB GYN News|
|Date:||Oct 15, 2003|
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