If you have to have an operation of any kind one of the first things you typically ask your doctor is “what are the risks?” However, sometimes your doctor or surgeon can’t give you an answer. That’s because until recently many post-surgery deaths were unforeseen and came as a surprise to physicians and patients’ families alike.
What is at issue here is not a death that comes as a result of the disease or surgical procedure for which the patient undergoes an operation, but rather the instance where an unrelated cardiac episode occurs after surgery, often days, weeks, or even months after their surgery.
Worldwide, more than 200 million adults have major non-cardiac surgery each year, and more than one million die within a month of their operations.
For years scientists have been trying to find out why patients die following what was a fairly routine surgery that was successfully conducted without any apparent problems. And, the surgeries were not always critical, overly dangerous operations. In fact, operations such as orthopedic surgery, for example total joint replacement, or general surgery, such as abdominal or vascular surgery, have been known to result in patient deaths from heart attacks long after the surgery for reasons other than the surgery itself.
“After surgery, heart attack can be a catastrophic complication,” says Dr. Peter Nagele, of the University of Washington in St. Louis. “It’s difficult to diagnose a heart attack following surgery because the pain medications patients receive often mask chest pain.
The culprit in many such cases is the heart protein known as troponins. Troponins are almost undetectable. Elevated troponin levels are an indicator of post-operative heart muscle damage (even in cases not involving cardiac surgery) and can lead to a myocardial infarction . Dr. G.A. Redfern of the University of Kwazulu-Natal, says “myocardial infarction remains a significant cause of morbidity and mortality.” He says many patients experience silent myocardial infarction episodes.
Until recently, doctors typically measured troponin levels in cardiac patients undergoing surgery, but not in patients having other types of operations. In particular, it was thought, if a surgery didn’t involve the heart or if the patient had no history of heart problems there was no need to test for troponins.
“Surgery is a major stress test,” says Dr. Nagele. “You are exposing someone to a major trauma, and those patients tend to be at a higher risk for heart attack. The presence of troponin in the blood represents a ‘red flag’ for potential problems during the first 30 days, and perhaps the first year following a major operation.”
Risk Can Extend For Years
According to research  conducted by Dr. Redfern patients experiencing a myocardial infarction (MI) after non-cardiac surgery have a hospital death rate of 15 to 25 percent. Even in episodes where the MI is not fatal, it remains a risk factor for cardiovascular death during the six months following surgery. And for patients who do experience cardiac arrest after surgery, death from the cardiac arrest is a risk for as much as five years after surgery.
P.J. Devereaux, MD, PhD, associate professor and cardiologist at McMaster University in Hamilton, Ontario concurs . He found that 12 percent of people who have a heart attack after surgery will die within 30 days, compared to two percent for patients who don't have a heart attack. But he says, “it is hard to foretell problems because two-thirds of patients who have heart attacks are not having any ischemic symptoms …” again because of the pain medication patients may receive after surgery – particularly within the first two days.
In a “meta-analysis” (research focusing on multiple studies) researchers  reviewed studies that in combination looked at more than 3300 patients and more than 450 deaths and concluded that an “increased troponin measurement after surgery is an independent predictor of mortality, particularly within the first year” and that “monitoring troponin measurements after non-cardiac surgery may allow physicians to better risk stratify and manage their patients.”
New Test Offers Hope
While until recently the mystery and mystification about troponin and post-operative cardiac arrests has begun to clear, a ‘silver bullet’ to address the problem has been lacking. But research reported in 2012 has come up with what may be a game changing solution - a simple blood test.
Researchers  found a test that could predict the risk of death when given during the first three days after an operation by measuring the level of troponin. The test is still being evaluated following an initial study with more than 15,000 patients. A follow up study will test 40,000 surgery patients.
“This blood test may make it easier to identify patients at the highest risk of death,” says Dr. Nagele, who participated in the study and says if the results of the studies are positive the test could become a routine part of post-surgery treatment. In the study’s initial phase there was a 30-day mortality rate of 1.9 percent among patients given the test. That compared to a mortality rate of 16.9 percent without the test. The researchers are working on a newer, more accurate version of the test, but as it has not (as of 2012) been approved by the U.S. Food and Drug Administration.
For now, anyone planning to undergo a surgical procedure should thoroughly discuss with his or her medical team what pre- and post-operative measures are in place to monitor and address troponin levels.
1. Perioperative Troponin Elevation - a lecture by G.A. Redfern, University of Kwazulu-Natal – January 28, 2011
2. Characteristics and Short-Term Prognosis of Perioperative Myocardial Infarction in Patients Undergoing Noncardiac Surgery: A Cohort Study. P.J. Devereaux, MD, et. al. Annals of Internal Medicine. 19 April 2011; 154(8):523-528.
3. Prognostic Value of Troponin and Creatine Kinase Muscle and Brain Isoenzyme Measurement after Noncardiac Surgery: A Systematic Review and Meta-analysis. Levy, Michael M.D., et. al. Anesthesiology: April 2011 - Volume 114 - Issue 4 - pp 796-806
4. Association Between Postoperative Troponin Levels and 30-Day Mortality Among Patients Undergoing Noncardiac Surgery. Journal of the American Medical Association - JAMA. 2012; 307(21):2295-2304.