McMaster University

McMaster University

Faculty of
Health Sciences

Study examines need for quick angioplasty for heart attacks

By Suzanne Morrison
Published: May 21, 2009
Shamir R. Mehta
Dr. Shamir R. Mehta, associate professor in the Michael G. DeGroote School of Medicine and director of interventional cardiology at Hamilton Health Sciences

McMaster University researchers have settled the question of how long patients with threatened or mild heart attacks should wait before undergoing angioplasty or bypass surgery.

In their global study published in today’s (Thursday, May 21) New England Journal of Medicine researchers found similar rates of death, recurrent heart attack or stroke in patients allocated to receive an invasive procedure very early after they arrived in hospital versus if they had their procedure a day and a half or more later.  However, a sub-group of patients (one out of three) who were at high risk of having another event did appear to experience a benefit if they underwent an early intervention.

"This is good news for patients and physicians," said the study’s lead investigator Dr. Shamir R. Mehta, an associate professor of medicine in the Michael G. DeGroote School of Medicine and director of interventional cardiology at Hamilton Health Sciences.

"While we have known for a long time that patients with a full blown heart attack benefit from receiving angioplasty as early as possible, we did not know the optimal timing of angioplasty in patients with threatened or smaller heart attacks," said Dr. Mehta. "These second group of patients represent a large burden to the health care system and outnumber patients with full blown heart attacks by about 2:1. They often respond well to initial therapy with aspirin and other anti-clotting medications."

Angioplasty is a technique for reopening narrowed or blocked arteries in the heart without major surgery. Bypass surgery reroutes blood around clogged arteries to improve blood flow and oxygen to the heart.

The question of optimal timing has important implications for the organization of advanced cardiac facilities in Canada, where geography can often impede ability to get patients into a center that does angioplasty in a timely fashion.

"In large parts of Canada that do not have timely access to these procedures, patients coming to hospital with small or threatened heart attacks can be treated with aspirin and other anticlotting medications and be transferred to a catheterization laboratory a few days later without undue harm. Higher risk patients and those with full blown heart attacks should still be transferred earlier," Mehta said.

In larger centres with easily accessible facilities, Mehta said these findings imply that resources should be directed at performing angioplasty in patients with large, full-blown heart attacks as soon as possible. "For patients with smaller or threatened heart attacks, only those who are at high risk (about 1 in 3) need to have angioplasty early. The majority can be safety treated a few days later."

The study, called Early versus Delayed Invasive Intervention in Acute Coronary Syndromes, randomly assigned 3,031 patients from 17 countries to an early intervention (within 14 hours/same day) or delayed (within 50 hours/waiting several days) intervention. The study is the largest randomized trial ever performed comparing invasive interventional strategies in this group of patients.

The Canadian-led global study was funded by the Canadian Institutes of Health Research (CIHR).

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