Abstract
We measured serial changes in myosin light chain-I (MLC-I) in 19 patients undergoing coronary recanalization for evolving myocardial infarction to elucidate whether analysis of MLC-I release kinetics is useful for the evaluation of myocardial salvage following coronary recanalization therapy.
All patients had a left anterior descending artery lesion (#6 or #7 according to the American Heart Association classification) in the infarction related artery, and received intravenous or intracoronary administration of tissue plasminogen activator or urokinase within 6 hours after the onset except for 3 cases with spontaneous recanalization and 2 cases with direct percutaneus transluminal coronary angioplasty (PTCA). Six control patients with left anterior descending artery lesions in the infarction related artery were given conventional therapy using intravenous urokinase without emergent coronary angiography.
The release kinetics of MLC-I following coronary recanalization therapy were divided into three patterns. Group A (n=7) showed two peaks with a larger first peak and a smaller second peak. Group B (n=5) showed two peaks with a smaller first peak and a larger second peak. Group C (n=7) showed a single late peak pattern of MLC-I release kinetics. The time need to obtain recanalization on coronary angiography was significantly longer in Group A compared to Groups B and C (5.72±1.11, n=6 vs 3.84+0.80 hours n=6, p<0.05). The left ventricular ejection fraction (LVEF) at the convalescent stage in Group A was significantly lower than that in Groups B and C (44.4+13 vs 62.0+15.0%, p<0.05).
Patients showing a two-peaked pattern with a larger first peak were consistent with patients with late repertused, less salvaged, and more depressed left ventricular function at the convalescent stage. MLC-I release kinetics were influenced by the wash-out phenomenon in cases of late reperfusion.
