Finding the causes of heart attacks and how to treat them

Before the mid-1970s, nobody fully understood the cause of heart attacks, and there was no treatment apart from rest and pain relief. This meant that survival rates were poor, and many of those who did survive went on to suffer long-term health problems.

Finding the cause of heart attacks

To be able to treat heart attacks, doctors first needed to understand what caused them. This was the discovery of BHF Professor Michael Davies in 1976, the first scientist to clearly show that almost all heart attacks are caused by blood clots in one of the coronary arteries that supply blood to the heart. This discovery, made at St George’s Hospital Medical School in London, came from his careful study of the hearts of people who had died from heart attacks. Professor Davies also found that these clots form where the arteries are narrowed by atherosclerosis (the build-up of fatty substances inside blood vessels).

This overturned the widely-held view that these clots were a result rather than a cause of heart attacks. Although Professor Davies carried out the work in the 1970s, his findings were so far ahead of their time that they only gained widespread international support in the 1980s. They are now in every textbook on heart disease.

Crucially, his BHF-funded breakthrough raised the possibility that drugs that reduce clotting could help to save lives after a heart attack.

Proving the benefits of anti-clotting drugs

This theory was to be tested by BHF Professor Peter Sleight and Dr Rory Collins (now BHF Professor Sir Rory Collins). They led a team of researchers in Oxford in the late 1980s, who set up the first large scale trial of anti-clotting drugs in thousands of heart attack patients. They found in the immediate aftermath of a heart attack, giving a “clot-busting” drug called streptokinase together with aspirin (which prevents more clots from forming) saved lives. Giving streptokinase and aspirin together decreased deaths after a heart attack by around 40 per cent. This trial, which we jointly funded, called ISIS-2, also found that the earlier this combination of medicines was given after a heart attack, the better the outcome for the patient.

Following the ISIS-2 trial, in the 1990s clot-busters became a life-saving revolution adopted across the world. However, with further advances in heart attack care, we now have even better treatments, in particular angioplasty (which reopens a blocked coronary artery). But for some people, clot-busting treatment is still life-saving, for example if they are too far away from a suitable hospital, and in parts of the world where angioplasty is less available. Clot-busting drugs also remain a mainstay for treatment of strokes.

First published 1st June 2021