Myocardial injury after non-cardiac surgery: Time to shed the ignorance

Abstract

Case vignette A clinical entry, after specialist referral of a patient who experienced a postoperative troponin elevation, reads as follows: 'Thank you for the referral. Reason for referral: postoperative troponin elevation following total hip replacement. According to the history, the patient was asymptomatic and comfortable in the ward. No ischaemic symptoms or electrocardiogram [ECG] changes noted. Vital signs were within normal limits. Assessment: isolated troponin elevation, expected in this patient population and not clinically significant. Recommendation: review patient for symptoms, no specific therapy required. ' After an uneventful hospital stay, the patient was discharged on the 4th postoperative day, but died 5 days later at home. The global surgical volume has increased to >300 million proce dures per annum. [1] Cardiovascular complications contribute to onethird of major perioperative morbidity and mortality, with perioperative myocardial infarction and myocardial injury after noncardiac surgery (MINS) accounting for 39% of all deaths within 30 days of noncardiac surgery. [2] These deaths are distributed equally between patients who sustain a postoperative myocardial infarction and MINS. [2] The burden of perioperative cardiovascular complications, therefore, has a major public health importance. The paucity of clinicians with an appreciation of the importance of perioperative myocardial injuries and the associated prognosis, and the knowledge necessary to manage this public healthcare burden, needs to be addressed. [3] Methods A literature search on MINS in the perioperative period was conducted using MEDLINE and the following search terms: 'myocardial injury' , 'noncardiac surgery' , 'mortality' , 'perioperative complications' , 'treatment' , 'prevention' and 'guidelines'. Additional reports were obtained by reviewing reference lists from the literature. Studies involving large cohorts with clear inclusion criteria and outcome data were reviewed. Reviews and smaller studies with local significance were also included. This open-access article is distributed under Creative Commons licence CC-BY-NC 4.0.

Prevalence of a postoperative troponin leak in patients with cardiac risk factors undergoing knee and hip arthroplasty in a South African population

“…[13,14] It is thought to be a stress-induced ischaemia resulting from a myocardial oxygen supply and demand mismatch. [15,16] Unfortunately up to 80% of these MIs are underdiagnosed, [17,18] as the classic symptoms such as chest pain may be atypical or even absent. [19] Because the mortality is reported to be similar to conventional MIs, [20][21][22] an aggressive diagnostic and therapeutic approach is needed.…”

“…The diagnosis of MINS relies heavily on cardiac biomarkers [15] such as a new high-sensitivity troponin T assay (hs-cTnT), which is the RESEARCH preferred biomarker in the diagnosis of MI, [23,24] as well as exclusion of known non-ischaemic causes of perioperative troponin elevation such as sepsis and burns. [16,24,25] Perioperative troponin surveillance is a simple and cost-effective method [26] and of vital importance in diagnosing MINS. [13,27] The test also provides important prognostic information [19,28] when identifying patients at risk of a fatal outcome.…”

“…There are currently limited published data on the prevalence of MINS in orthopaedic-specific patients in South Africa (SA), and perioperative measurement of troponin levels is not considered standard protocol for patients undergoing arthroplasty. [16,32] In addition, there is currently insufficient information to successfully compare patient comorbidities in different arthroplasty procedures.…”

“…We hypothesise that there may be an underdiagnosis of MINS, specifically in the domain of arthroplasty, and establishing a statistical significance in the prevalence rate could raise awareness and, along with the provision of early optimal medical intervention, reduce morbidity and mortality. [16,33]…”

Anaesthesia in South Africa

“…Third, the management of myocardial injury after non-cardiac surgery (MINS) is reviewed. [13] MINS is defined as an elevated postoperative cardiac troponin level resulting from myocardial ischaemia, without evidence of a non-ischaemic cause. The perioperative context contributes to the pathophysiology of relative myocardial hypoperfusion and ischaemia, which differentiates MINS from myocardial infarction in non-surgical patients.…”