Methylenetetrahydrofolate reductase (MTHFR) C677T genetic polymorphism and late infarct-related coronary artery patency after thrombolysis.

In patients with acute myocardial infarction (AMI), a persistently occluded infarct-related artery (IRA) is associated with unfavorable prognosis and genetic factors may be contributing factors to thrombolysis failure. One-hundred and one consecutive patients treated with intravenous thrombolysis during AMI were blind-tested for methylenetetrahydrofolate reductase (MTHFR) and circulating homocysteine levels and underwent protocol angiography 14 +/- 6 days after the event. IRA was patent in 61 patients and occluded in 40. Overall MTHFR 677TT frequency was 22%. Patients with MTHFR 677TT homozygosis had higher prevalence of occluded IRA (73%) versus those with MTHFR 677CT/CC genotype (30%, P < 0.001); MTHFR 677TT genotype predicted independently the risk of IRA occlusion with a specificity of 90% (odds ratio 3.8, 95% confidence interval 1.1-9.1; P = 0.03). Moreover, patients with occluded IRA and MTHFR 677TT genotype had the highest homocysteine levels (21 +/- 7.6 micromol/l vs. < or =14.9 +/- 3.8 micromol/l; P = 0.011). In patients with AMI, MTHFR 677TT homozygosis is independently associated with a persistently occluded IRA after thrombolysis. This finding may have pathophysiological and therapeutic implications for recanalization strategies in patients with AMI.