INFLUENCE OF CARBON-MONOXIDE (CO) ON THE EARLY COURSE OF ACUTE MYOCARDIAL-INFARCTION

Objective: To clarify the influence of an elevated carboxyhemoglobin ( COHb) blood level on the course of acute myocardial infarction and to evaluate the administration of supplemental oxygen on the COHb level a nd the incidence of complications. Design: Prospective clinical study with randomized, unblinded intervention. Setting: Coronary Care Unit o f a university hospital. Patients: 78 consecutive patients with acute myocardial infarction. Excluded were patients with severe dyspnea, pul monary edema or any other medical indication for supplemental oxygen t herapy. Interventions: Randomized therapy with 4 l/min oxygen in 35 pa tients. Measurements and results: COHb was measured at admission and 4 h later. The incidence of serious arrhythmias and the maximal creatin e kinase (CK) values were recorded. In patients with initial COHb grea ter than or equal to 5%, there were significantly more arrhythmias and significantly higher maximal CK values than in those with normal COHb at admission (89 vs 33%, p < 0.001; and 1897 +/- 1602 u/l vs 960+/-97 u/l, p = 0.05). This effect was seen only in patients with Q-wave inf arction, not in those with non-q-wave infarction. Supplemental oxygen had no effect on the incidence of arrhythmias. Conclusions: We conclud e that myocardial infarction patients with acute Q-wave infarction and increased COHb levels at admission suffer a more severe course of the disease, This outcome was not influenced by oxygen therapy. Whether t his finding indicates a causal relationship and whether higher oxygen concentrations would favorably alter the course of acute myocardial in farction remain to be determined.