High-dose oral multivitamins and minerals did not reduce CV events in patients after MI, according to recent study findings.
However, the researchers observed considerable nonadherence and withdrawal among participants, which may limit the conclusions that can be drawn.
Gervasio A. Lamas, MD, and colleagues conducted the Trial to Assess Chelation Therapy (TACT), a double blind, placebo-controlled, 2 x 2 factorial, multicenter, randomized trial of 1,708 patients aged at least 50 years (median age, 65 years) who experienced MI at least 6 weeks before enrollment and had serum creatinine levels ≤176.8 mcmol/L (2 mg/dL). The median time from qualifying MI was 4.6 years (interquartile range, 1.6-9.2 years) before enrollment.
Gervasio A. Lamas
About half the patients (n=853) were assigned an oral 28-component high-dose multivitamin and multimineral mixture; the remaining 855 received placebo.
The primary endpoint was time to all-cause mortality, recurrent MI, stroke, coronary revascularization or hospitalization for angina.
Median follow-up was 55 months (interquartile range, 26-60 months). Patients in the vitamin group received therapy for a median of 31 months (interquartile range, 13-59 months), and those in the placebo group received placebo for a median of 35 months (interquartile range, 13-60 months). In both groups, 76% of participants completed at least 1 year of treatment (P=.98). The percentage of patients who completed at least 3 years of oral therapy was 47% in the vitamin group and 50% in the placebo group (P=.23).
In both groups, 46% of participants discontinued their regimen (P=.67), and 17% of patients withdrew from the study. The rate of discontinuation because of adverse events was 9.9% in the vitamin group and 7.9% in the placebo group (P=.34).
The primary endpoint occurred in 27% of those in the vitamin group vs. 30% in the placebo group (HR=0.89; 95% CI, 0.75-1.07). The composite of CV-related death, MI or stroke occurred in 11% of those in the vitamin group vs. 13% in the placebo group (HR=0.82; 95% CI, 0.62-1.07).
Lamas, of Mount Sinai Medical Center, Miami Beach, Fla., and colleagues found no evidence of harm from vitamin therapy in any evaluated category of adverse events.
“Although this trial does not support the routine use of this high-dose oral multivitamin regimen for all patients who have had MI, the reduced statistical power due to a small difference between groups, as well as nonadherence to the study regimen, limits the conclusion of nonefficacy,” Lamas and colleagues wrote. “Future studies of this particular regimen would have to consider a smaller effect size than we estimated, as well as the barriers to adherence that were identified.”
Disclosure: Some researchers report financial ties with AstraZeneca, Eli Lilly, Medtronic and Prezacor.