Patients who suffer a severe heart attack have a much better chance of surviving and avoiding severe complications if they are treated with a new heart procedure that not only unblocks the artery that caused the heart attack, but also removes blockages in other arteries.

These were the findings of a randomized trial called the Preventive Angioplasty in Myocardial Infarction (PRAMI) Trial, whose interim results were so clearly in favor of the preventive procedure that it was stopped early.

The findings were presented on Sunday at the European Society of Cardiology Congress 2013 in Amsterdam, and they are published online this week in the New England Journal of Medicine.

Heart attacks (myocardial infarctions) occur when an artery that supplies blood to the heart is partly or completely blocked by a clot, causing some of the heart muscle (myocardia) to die (become infarcted).

The most severe type of heart attack is known as a STEMI (short for ST segment elevation myocardial infarction), and it occurs when the blood clot completely blocks the heart artery.

The trial investigators hope their results will help clinicians decide how to approach procedures to remove blockages in heart arteries following severe (STEMI) heart attacks. These procedures are called percutaneous coronary interventions (PCIs).

During a PCI, doctors perform an angioplasty (an artery-widening operation) where they insert a thin tube or stent into the patient’s blocked artery to keep it open and allow blood to flow through to the heart. While they are doing this, they can see if other arteries are also blocked. The trial investigated whether unblocking these could prevent further heart attacks, complications and deaths.

Lead investigator Dr. David Wald says:

When a patient is admitted with an acute myocardial infarction, it is known that PCI to the blocked culprit artery is life-saving, but there is uncertainty as to whether doctors should undertake preventive PCI in vessels that are partially blocked but did not cause the myocardial infarction. This is a common clinical dilemma.”

The committee in charge of monitoring the trial called for it to stop early when they saw an analysis of early results that showed the patients receiving preventive PCI were faring much better compared with patients who only had PCI to remove the blockage that caused their heart attack.

Wald explains:

The results of this trial show that in this situation preventive PCI […] reduces the risk of cardiac death, a subsequent myocardial infarction or angina resistant to medical therapy, by about two-thirds.”

He says the new evidence should prompt a revision of the current guideline, which in the UK says doctors should treat only the artery that caused the STEMI heart attack, because of lack of evidence in favor of preventive PCI.

In the trial, 465 patients undergoing emergency PCI for serious heart attacks (the vast majority of the STEMI type) who also had blockages in other blood vessels, were randomized just before the procedure to receive either preventative PCI (234 patients) or culprit-only PCI (231).

Over a follow-up of nearly 2 years, 21 patients in the preventive PCI group and 53 in the culprit-only group either died, had another heart attack or developed refractory angina.

This represents an absolute risk reduction of 14 per 100 in the preventive PCI group and a relative risk reduction of 65%, compared with the culprit-only group.

Wald says that on average, preventive PCI extends the procedure time by around 20 minutes, adding that “the initial costs of preventive PCI are higher but there will be reduced costs thereafter, with a reduced need for subsequent hospital admissions, cardiac investigations and revascularisation procedures.”

In 2011, researchers in Italy reported that patients who receive PCI after STEMI heart attacks are often back in hospital and suggested their findings called for timely and effective preventive and treatment strategies for such patients.