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Inferior MI increases CABG risk more than anterior MI
Among patients undergoing coronary artery bypass graft (CABG) surgery, those with a history of previous myocardial infarction (PMI) have poorer postoperative cardiovascular outcomes than those without. However, it remains unclear whether there are differences in outcomes after CABG between patients with anterior PMI and those with inferior PMI.
Fukui et al retrospectively reviewed the medical records of 310 patients with a history of PMI who underwent CABG without valve replacement. PMI was defined as MI occurring more than 30 days before surgery. PMI was confirmed most commonly by scintigraphy, although ECG, echocardiography and MRI were also used. Patients with lateral MI or a combination of anterior and inferior MI were excluded. A total of 151 patients with anterior PMI and 159 patients with inferior PMI were included in the study.
Investigators found that patients with inferior PMI were older (mean (SD) 68.3 (9.2) vs 65.5 (11.0), p = 0.015), had a greater number of diseased vessels per patient (2.9 (0.3) vs 2.8 (0.5), p = 0.009), had a lower incidence of diabetes (44.0% vs 58.3%, p = 0.02) and a higher rate of mitral regurgitation (18.2% vs 8.6%, p = 0.02) than patients with anterior PMI. There were no differences between the groups with respect to operative technique, number of grafts and completeness of revascularisation.
Patients with a history of inferior PMI were observed to have a higher incidence of respiratory failure, greater requirement for haemodialysis, increased operative mortality and a higher combined clinical end point of operative death and major complications (table 1).
Multivariate analysis revealed inferior PMI to be the only independent predictor of major postoperative complications, including death (p = 0.007). The mechanistic explanation for this remains unclear; however, potential right ventricular dysfunction after prior inferior MI may adversely affect respiratory function and renal perfusion. Further large-scale randomised control trials may help …