A call is made today for increased awareness of 'silent' heart attacks that may follow surgery. In a session at this week's Annual Congress of the Association of Anaesthetists of Great Britain and Ireland (AAGBI), Professor Daniel I. Sessler, Michael Chudahy Chair of the Department of Outcomes Research at the Cleveland Clinic, Ohio, USA, will present evidence that about one in 11 patients having major non-cardiac surgery will have a heart attack, and among these one in 10 will die within 30 days of the operation.

Some 80% of postoperative heart attacks are clinically silent, with no physical signs or symptoms to show that they have occurred. It is only through testing blood for the biomarker troponin that such heart attacks can be detected. Prof. Sessler will emphasise that currently few postoperative patients get troponin screening, but available data suggest that many more should so that timely treatments can be provided for those who have a heart attack.

"Blood concentration of troponin is the best indicator of a post-surgical heart attack. Furthermore, the test for troponin is inexpensive, quick, and accurate." says Prof. Sessler. "Many of these patients appear outwardly to be recovering well from their surgery. In four of five patients who have a postoperative heart attack, there are no clinical symptoms or signs: no chest pain or shortness of breath, and electrocardiograms and echocardiograms are normal. Clinicians will thus miss most of these heart attacks without specific blood testing for troponin."

There are different options for treating such postoperative heart attacks, Prof. Sessler explains, but patients should at very least be started on aspirin. Other options include angiography and coronary artery stenting, or treatment with anticoagulant drugs. How to prevent heart attacks also remains unknown, although POISE-2, a major trial of low-dose clonidine and low-dose aspirin involving 10,000 patients, will finish by the end of 2013.

"Available data, though, indicate that low blood pressure during surgery is strongly associated with both kidney injury and heart attacks. In most cases, anaesthesiologists can prevent levels of hypotension that might be dangerous by giving less anaesthesia or drugs that raise blood pressure." concludes Prof. Sessler.

AAGBI President Elect Andrew Hartle commented 'These are important findings with implications for improving patient care and making surgery even safer than it already is."

Notes

What is moderate to high risk surgery?

This is defined as operations on people aged 45 and over requiring at least one night in hospital

How many surgical procedures a year?

There are approximately 240 million non-cardiac surgeries carried out globally each year. Prof Sessler estimates that at least one third of these would be moderate-to-high risk surgeries.

Electrocardiograms look at the electrical activity of the heart

Echocardiograms use ultrasound to show how the heart muscle is contracting in real time

Angiography involves injecting dye to see the blood supply to the heart, and allows cardiologists to open blocked arteries with drugs or stents to restore the interrurpted blood supply that causes a heart attack.

Anticoagulant drugs thin the blood and prevent from clotting, although they are useful in treating heart attacks, they increase the risk of bleeding associated with surgery.