New cholesterol test could help predict heart attack

MUNICH, Germany — A simple test that scrutinizes bad cholesterol more closely may more reliably predict who is going to have a heart attack, new research indicates.

The current test measures total cholesterol and the breakdown of good HDL and bad LDL cholesterol. The new test, discussed Tuesday at the annual meeting of the European Society of Cardiology, instead measures the ratio of bad LDL cholesterol particles to good HDL cholesterol particles.

The smaller bad particles are called apolipoprotein B molecules and the good ones are called apolipoprotein A1 molecules. A ratio of 1 to 2 is considered low risk, while a ratio approaching 1 to 1 would be considered high risk, and anything over that — where small LDL particles dominate — would be very high risk.

If the LDL is mostly made up of small particles, that's bad because they are dense and are the building blocks of plaque. The big ones are more easily carried away by the blood flow.

The test was used in a major study investigating what causes heart attacks because researchers suspected it might be a better predictor of heart trouble than standard cholesterol tests.

The study followed 29,000 people in 52 countries. It compared 15,000 who had suffered a first heart attack with someone of the same age, sex and location who had not had a heart attack.

It found the standard cholesterol test did not correlate well with heart attacks, but that the new method was a better indicator. A high ratio of small LDL molecules to good cholesterol turned out to be the most important factor linked to heart attack risk, before even smoking.

Patients with the worst test results were about four times more likely than those with the best score to have a heart attack.

"Globally, 50 percent of the risk of a heart attack is predicted by the apo B/apo A1 ratio," said the study's leader, Dr. Salim Yusef, a professor of medicine at McMaster University in Canada.

"I was impressed," said Dr. David Wood, a cardiologist at Charring Cross Hospital in London who was not connected with the research. "It made a significant independent contribution to risk prediction which was better than the other risk markers."

However, Wood said it is too early to tell whether the new test will supplant the standard cholesterol test in the near future because it has been a struggle to get doctors to routinely test for cholesterol, even with the method that has been around for at least a decade.