Optimal timing of surgical revascularisation after acute myocardial infarction

The article by Voisine et al. [1] highlighting the influence of patient age and time elapsed between acute myocardial infarction (AMI) and isolated CABG surgery on operative mortality, which appeared in the March 2006 issue of EJCTS, caught our attention. The results of this retrospective study suggest that operative mortality is significantly increased between 6 h and 1 week after AMI, especially in older patients. In the case of AMI, the dogma of ‘time is muscle’ has been challenged by Voisine et al. [1] for early surgical revascularisation as ‘inappropriate timing is excessive mortality’. We wish to congratulate the authors on an interesting paper especially in the era of primary reperfusion interventions yielding a growing population of AMI survivors; however, we feel that certain issues must be addressed. Analyses of the New York State Cardiac Surgery Registry including 44,365 patients clearly demonstrated that patients with transmural and non-transmural AMI have different trends in mortality when the time course is taken into consideration [2]. Mortality for the non-transmural group peaked if the operation was performed within 6 h of AMI, then decreased precipitously. On the other hand, mortality for the transmural group remained high during the first 24 h after AMI, before trending downward. Thus, it is questionable whether transmural and non-transmural AMIs may be included in one model. The investigators were aware of this important issue and mentioned as a limitation of the study. However, they failed to mention why they did not make any distinction between transmural and subendocardial AMIs. Furthermore, the occurrence of recurrent ischemic events post-MI is declining noticeably over time but continue to be important indicators of post-MI outcomes [3]. We believe that the rates of unstable angina, recurrent MI, hemodynamic state of the patients and risk index should be clearly mentioned and discussed in the authors’ series which will provide the reader with a better view of their cohort of patients. Extensively calcified aorta, previous open heart operations did not seem to be risk factors for patients undergoing CABG following AMI on multivariate analysis in contrary to other studies [4]. Taking this into account, it is essential that the authors demonstrate all the variables tested on their multivariate analysis. Finally, the authors provided only the survival data with more limited data on other outcomes and it would be of interest to know the cause of death of patients in both groups (hemorrhagic vs ischemic). Dr Voisine’s comments in the conference discussion deserve attention regarding no perioperative deaths among 35 patients operated on within the first 24 h in the last 2 years of their experience. According to our experience, we observe similar outcomes and on-pump beating heart revascularisation can be efficacious in patients with unstable haemodynamics or cardiogenic shock early after AMI. Thus, there are persisting gaps in knowledge regarding optimum timing and best strategy for surgical revascularisation after AMI. As more is learned about the timing of surgery, it might be worth focusing on the burden of post-MI recurrent ischemic events and sudden death with or without surgery, looking at the results of subgroup analysis and auditing the surgical mortality.