Patients undergo non-cardiac surgery with the hope that it will extend their lives, or improve its quality. It is a tragedy then that some of these patients will suffer perioperative myocardial injury that will go undetected; some of these patients will die within 30 days due to this complication. Recent studies have focused on how best to identify these patients at risk of death. From this research the following has become clear:

1. Troponin elevation after non-cardiac surgery occurs commonly.

Worldwide, over 200 million adults undergo major noncardiac surgery annually,¹ and more than 10 million of these patients will suffer postoperative troponin elevation during the first 30 days after surgery.² In the placebo group of the POISE Trial, a large randomized controlled trail of over 8000 patients, 1.4% of patients suffered vascular death, 0.5% suffered stroke, 0.5% suffered nonfatal cardiac arrest, and 5.7% suffered myocardial injury in the first 30 days.³ These data suggest that myocardial injury, as measured by postoperative troponin elevation, is the most common major vascular complication after non-cardiac surgery.

2. Patients who suffer postoperative troponin elevation are at increased risk of death after their surgery.

The VISION study is a large international prospective cohort study evaluating major vascular complications in patients ≥45 years of age undergoing non-cardiac surgery that requires hospital admission. In this study patients have daily troponin T (TnT) measurements for the first 3 days after surgery. In a recent publication based on the first 15,133 patients from the VISION Study, peak postoperative TnT measurement in the first 3 days after surgery was an independent predictor of 30-day mortality.² VISION demonstrated that one in 25 patients with a peak TnT measurement of 0.02 ng/ml, one in 11 patients with a peak TnT measurement of 0.03-0.29 ng/ml, and one in six patients with a peak TnT measurement >0.30 ng/ml died within 30 days of surgery. The data also suggests that myocardial injury detected through TnT elevations may explain 42% of deaths that occur after surgery.

Furthermore a meta-analysis of 10 studies (n=1728) is an extension of the VISION data in that the meta-analysis demonstrated that an elevated postoperative troponin predicted mortality at 12 months after non-cardiac surgery.⁴ An additional study of abdominal aortic surgical cases (n=1135) found a troponin I elevation >1.5 ng/mL independently predicted in-hospital mortality.⁵

3. Clinical symptoms usually will not identify these patients.

The majority of postoperative troponin elevations (74%) occur within 48 hours of surgery. In this period most patients are receiving analgesic medication, and 65% of patients with a troponin elevation do not experience any ischemic symptoms.⁶ Importantly, the mortality rate of patients with post-operative troponin elevation without symptoms is not different from those who do experience symptoms.⁶

For these reasons we advocate for routine postoperative troponin measurement after not only vascular surgery, but also after high risk surgery (i.e., major general surgery, major neurosurgery, urgent/emergent surgery), as well as in patients older than 65, or patients with established atherosclerotic disease or risk factors for atherosclerotic disease. Postoperative troponin monitoring is a simple test which could easily be incorporated into routine postoperative care. Its powerful prognostic ability will enable the clinician to identify patients who will die within 30 days of surgery.

As of yet no effective treatment of these patients has been established, but data suggest that their prognosis may be modifiable. Acetylsalicylic acid (ASA) and statin therapy is strongly supported by data from non-operative trials and data from the POISE Trial supports their use in patients who suffer perioperative myocardial injury. Currently many patients with postoperative troponin elevation do not receive these medications.⁶ What is clear is that there is an urgent need for clinical trials to identify effective therapies to improve the outcomes of patient with myocardial injury after non-cardiac surgery.

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References

1. Weiser TG, Regenbogen SE, Thompson KD, Haynes AB, Lipsitz SR, Berry WR, et al. An estimation of the global volume of surgery: a modelling strategy based on available data. Lancet 2008;372:139-44.
2. Devereaux PJ, Chan MT, Alonso-Coello P, Walsh M, Berwanger O, Villar JC, et al. Association between postoperative troponin levels and 30-day mortality among patients undergoing noncardiac surgery. JAMA 2012;307:2295-304.
3. Devereaux PJ, Yang H, Yusuf S, Guyatt G, Leslie K, Villar JC, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial. Lancet 2008;371:1839-47.
4. Levy M, Heels-Ansdell D, Hiralal R, Bhandari M, Guyatt G, Yusuf S, et al. Prognostic value of troponin and creatine kinase muscle and brain isoenzyme measurement after noncardiac surgery: a systematic review and meta-analysis. Anesthesiology 2011;114:796-806.
5. Le Manach Y, Perel A, Coriat P, Godet G, Bertrand M, Riou B. Early and delayed myocardial infarction after abdominal aortic surgery. Anesthesiology 2005;102:885-91.
6. Devereaux PJ, Xavier D, Pogue J, Guyatt G, Sigamani A, Garutti I, et al. Characteristics and Short-Term Prognosis of Perioperative Myocardial Infarction in Patients Undergoing Noncardiac Surgery: A Cohort Study. Ann Intern Med 2011;154:523-8.

Keywords: General Surgery, Troponin

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