In recent years, studies have shown a link between elevated plasma homocysteine levels and coronary heart disease. Studies have also shown that the B vitamins folic acid, vitamin B12, and pyridoxine lower plasma homocysteine levels. A group of researchers who previously demonstrated an association between elevated homocysteine levels and the occurrence of restenosis after percutaneous coronary angioplasty set out to test whether lowering homocysteine levels using B vitamins would lower the rate of restenosis after angioplasty. Their results are published in the New England Journal of Medicine.

Lower homocysteine associated with less restenosis

In this prospective, randomized, double-blind trial, 205 patients who underwent successful coronary angioplasty were randomly assigned to receive either vitamin treatment or placebo. The vitamin treatment consisted of a combination of 1 mg folic acid, 400 µg vitamin B12, and 10 mg pyridoxine. The primary endpoint studied was restenosis of the treated vessel by 50% or more within six months; the secondary endpoint was a composite of major adverse cardiac events, including nonfatal heart attack, revascularization of the target lesion, and death from cardiac causes.

Of the 205 patients initially enrolled, 177 (86%) remained in the study for collection of angiographic data at six months after angioplasty. The occurrence of restenosis was significantly lower in patients receiving the treatment than in those receiving the placebo; 19.6% of vitamin patients (18 of 92) reached the primary endpoint of restenosis, compared with 37.6% of the control patients (32 of 85) (p=0.01). This corresponds to a relative risk reduction of 48% with the vitamin treatment (RR 0.52, 95% CI=0.32-0.86).

Patients in the vitamin group also had a lower rate of major adverse cardiac events (12.7% versus 24.5%, p=0.055; RR 0.52, 95% CI=0.28-0.98).

As expected, homocysteine levels at follow-up were significantly lower in patients receiving vitamins than in those receiving placebo (7.2±2.4 vs. 9.5±3.6 µmol/L, p<0.001).

Further support for B vitamins and cardiac health

This study adds to the growing body of evidence that treatment with B vitamins lowers plasma homocysteine levels, and that lowering homocysteine levels may be significant for cardiac health. The results are important because heart disease remains the number-one killer of American adults, and because restenosis is a potentially serious complication of angioplasty, a common treatment for coronary artery disease.

Not yet cause-and-effect

While these results are promising, they do not, however, prove that the benefit observed was due solely to lower homocysteine levels; the vitamin treatment may have had other, unknown effects.

Nonetheless, because the treatment is relatively inexpensive and has minimal side effects, the researchers maintain that it should be considered as adjunctive therapy for patients undergoing coronary angioplasty.