Many Heart Attacks Go Undetected After Surgery

Heart attacks after noncardiac surgery may go unnoticed without simple blood test

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) Heart attacks often come with warning signs, such as pain or discomfort in the chest. Attacks after surgery, however, may go undetected unless patients have a blood test that can spot heart trouble.

Every year, more than 8 million adults worldwide experience a heart attack or heart injury after surgery. Within a month, 10 percent of those individuals die.

According to a new investigation, about 85 percent of those heart attacks and injuries may go unnoticed because patients may not experience typical symptoms. An easy blood test, however, can identify a potential heart problem and increase a patient’s chance of survival.

"If undergoing surgery, consider a blood test that indicates heart injury."

P.J. Devereaux, MD, head of cardiology and the Perioperative Cardiovascular Clinical Program at the Juravinski Hospital and Cancer Centre, Hamilton Health Sciences, Ontario, led the study, following 15,065 patients, age 45 and older, who underwent noncardiac surgery.

During the first three days following surgery, all participants had a blood test measuring their level of troponin T — a protein essential to heart muscle contraction. It is released into the blood when the heart muscle is injured.

Doctors assessed individuals with elevated troponin T levels for heart damage using an EKG, or electrocardiogram (a test that records the heart’s electrical activity).

From these tests, researchers discovered that 1,200 patients (about 8 percent) suffered myocardial injury, or damage to the heart muscle because of ischemia (a restriction of blood supply and oxygen to the tissue).

Only 15 percent of participants who had heart attacks post-surgery, however, suffered any typical symptoms — such as chest pain and pressure, shortness of breath or pain in the neck, jaw or arm.

"Most surgical patients who suffer a heart attack or injury will do so within the first 48 hours after surgery," said Dr. Devereaux in a press release. "During this time, most of these patients are typically taking pain medications, which can mask the symptoms of a serious heart injury."

This may explain why 85 percent of those with a heart attack had no symptoms. The authors underscored the importance of monitoring troponin T in these patients. Without it, more heart injuries would have gone undetected and untreated.

They noted that, of all post-surgery complications, heart attack is the number-one reason patients die within 30 days of an operation.

The authors also recommended that a new diagnosis that they used called Myocardial Injury after Noncardiac Surgery (MINS), would be helpful for physicians because it includes a broader definition of the traditional one used to diagnose heart attacks today.

They wrote that their definition is broader than the definition of myocardial infarction [tissue death] in that it includes not only myocardial infarction but also myocardial injuries due to ischemia.

The study was published in the March issue of Anesthesiology. Research was coordinated by the Clinical Advances Through Research and Information Translation (CLARITY) project office in the Department of Clinical Epidemiology and Biostatistics at McMaster University and the Population Health Research Institute (PHRI), at the Hamilton Health Sciences, McMaster University, Hamilton, Ontario, Canada. Roche Diagnostics provided the troponin T assays and some financial support. Dr. Devereaux has received other funding from Roche Diagnostics and Abbott Diagnostics for investigator-initiated studies.

Review Date: 
February 22, 2014
Last Updated:
February 24, 2014