B Vitamins May Be Risky After Heart Surgery
Folate Combination Linked to Artery Narrowing Following Angioplasty
Reading Between the Results continued...
"While the overall results of this study show a negative effect from these vitamins, that detrimental effect was not present in patients who had high homocysteine levels."
Another possible explanation for the study findings: At the start of Lange's study, the use of cholesterol-lowering statin drugs such as Lipitor and Zocor were used by a surprisingly low number of patients -- only 38% of those getting the vitamins and 42% of those on placebo drugs.
"And that may have been enough to shade the results," Siegel tells WebMD. These drugs are routinely prescribed to heart patients, and especially candidates for angioplasty.
Howard C. Herrmann, MD, director of interventional cardiology and cardiac catheterization laboratories at the University of Pennsylvania Medical Center, wrote an accompanying editorial to Lange's study and notes several differences between this study and the study that showed a benefit from vitamin therapy.
For one thing, higher doses of vitamin supplements were used in Lange's research, especially B-6, says Herrmann. "We don't really know the role of B-6 and B-12, other than they work together with folate to reduce homocysteine," he tells WebMD.
The people studied in the two trials were also different. The study that showed a benefit from vitamin supplement had more smokers and people with diabetes -- factors that can boost homocysteine levels. The study also showed the biggest benefit from vitamin therapy occurred in patients treated with angioplasty alone, rather than those getting angioplasty with stents. In Lange's study, all patients got stents.
Lessons to Learn
What does this all mean?
"Folate supplementation has been considered safe and completely benign," Herrmann tells WebMD. "And even if its effect on [renarrowing] wasn't as great as what was previously shown, you could still say, 'why not give it to people?' But now, there's a study that suggests it could be harmful, so we may need to rethink that."
Something else to reconsider: Priorities in treating angioplasty patients, he says. Since the 1990s, more patients have been treated with newer, second-generation stents that are coated with medication that helps prevent renarrowing, which has reduces the risk from about 20%-30% to single digits.
"[Renarrowing] is not as big an issue these days, with the advent of drug-eluting stents, so our focus should be more on preventing new cardiovascular disease," he says.