Postoperative myocardial injury: Trying to square the circle

The early detection and management of postoperative myocardial injury (PMI) is a major challenge in cardiovascular medicine. According to data from the POISE (PeriOperative ISchemic Evaluation) trial, 5.0% of patients undergoing non-cardiac surgery experience myocardial infarction, mostly (74.1%) within 48 hours after surgery.1 The identification of a postoperative myocardial infarction can be rather tricky, insofar as symptoms related to myocardial ischaemia in these patients are often subtle and may be masked by anaesthesia or pain-killers.2 Several aspects of PMI were extensively reviewed by Verbree-Willemsen et al. in the current issue of the European Journal of Preventive Cardiology.3 The topic was also addressed in the recent joint position statement of the European Society of Cardiology, American College of Cardiology, American Heart Association, World Heart Federation regarding the fourth universal definition of myocardial infarction.4 Verbree-Willemsen and coworkers proposed a panel of advisable tests in the follow-up assessment of patients with PMI, based on physical examination, electrocardiogram (EKG), biomarkers and imaging.3 This approach, associated with an appropriate risk-stratification assessment before major non-cardiac surgery, should be implemented in order to prevent the occurrence of PMI and to improve the management of such patients (Figure 1). However, as pointed out by Verbree-Willemsen et al.,3 there are still several outstanding issues with regard to PMI. First, there are no data regarding the preoperative assessment of biomarkers such as troponins and natriuretic peptides in patients with an impaired cardiovascular risk profile. Of note, recently it was demonstrated that a rising pattern of high-sensitivity troponin T (hsTropT) measured 6–12 h after surgery and daily for three days exhibiting an increase in hsTropT concentration is strongly predictive of poor outcomes.5 Given this magnitude, guidelines recommend to assess troponins in high-risk patients undergoing major surgery 24 h after the operation.4 Besides troponins, natriuretic peptides, EKG and echocardiography may be useful for patients undergoing high-risk surgery.4 It must also be considered that remarkable sex-related differences are present with regard to preoperative risk stratification. Indeed, as recently reviewed by Nicolini et al.,6 females undergoing aortic surgery are burdened by poorer postoperative outcomes. The underlying bedrock of this difference should be investigated by future research. Management of postoperative myocardial injury according to Verbree-Willemsen et al.3 EKG: electrocardiogram; URL: upper reference limit. Second, there is a lack of evidence regarding the potential beneficial effect of preoperative exercise training, and selective preoperative myocardial revascularization on reducing PMI. Among all preoperative measures, only the administration of statins, both in naïve patients as well as a reload in statins users, appears effective and without relevant side effects,7 whereas the use of other drugs led to either inconclusive results or to increased incidence of undesirable side effects. With regard to non-pharmacological intervention, recently two meta-analyses demonstrated a positive association between major postoperative outcomes (complications, functional capacity) with preoperative exercise training8 as well as early commenced aerobic exercise9 in patients undergoing elective cardiac surgery. Future studies should prove whether these findings are translatable also into patients undergoing non-cardiac surgery. Interestingly, a randomized controlled trial performed in a tertiary centre in Australia on 187 patients with a post-surgery troponin elevation showed that there were no differences in terms of one-year mortality between the group randomized to an intensive cardiological monitoring (admission to coronary care unit within 24 h, monitoring with telemetry) and the group allocated to the standard care treatment.10 A possible explanation for this finding is that PMI might be driven also by non-cardiac factors. Indeed, several studies performed with coronary computed tomographic angiography reported that 30–50% of patients with PMI displayed no significative obstruction of the coronary arteries, leading to the speculation that the postoperative stress or the occurrence of systemic complications (infections or renal failure) may lead to an insufficient perfusion of the myocardial tissue.11–13 In other words, PMI might belong either to type I myocardial ischaemia (rupture of a vulnerable plaque) or to type II myocardial ischaemia (oxygen mismatch or higher demand), according to the models proposed by the recent fourth universal definition of myocardial infarction.4 These pathophysiological considerations may shed new light on PMI, warranting a multidisciplinary approach in its management. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. The author(s) received no financial support for the research, authorship, and/or publication of this article.