Researchers push germ theory for heart disease

Web posted November 11, 1997

Associated Press

ORLANDO, Fla. -- The war on heart disease has been, without doubt, one of the biggest battles of 20th century medicine, and with many victories along the way.

Overall, death rates from heart disease have been on the decline, thanks to interventions such as angioplasty, the technique in which blocked arteries are opened with a tiny balloon that forces an opening through the blockage. Nevertheless, heart disease remains the No. 1 cause of death nationwide.

Even though many people know how to prevent heart disease, know the dictums against fatty foods, smoking and lack of exercise, chapter and verse, interventions have not reduced its incidence as dramatically as some doctors would have preferred.

As the American Heart Association began its 70th Scientific Sessions Sunday in Orlando, Fla., a renegade group of scientists was laying the groundwork for the germ theory of heart disease.

Evidence has been building for years, but vascular biologists have yet to home in on the specific mechanisms by which microorganisms can cause blocked arteries that lead to heart attacks.

Microbial predators suspected in heart disease are well known but for other medical reasons: Chlamydia pneumoniae, which can invade the lungs and cause pneumonia; cytomegalovirus, a member of the herpes family that can be harbored in the salivary glands in a lifelong infection, and Helicobacter pylori, now widely believed to be the cause of peptic ulcers.

A team from the University of Utah in Salt Lake City, was to present evidence on all three organisms and how these microscopic culprits are believed to be related to vascular damage. A contradicting study by a nationwide team of researchers from the National Heart, Lung and Blood Institute, Johns Hopkins University and the Baylor College of Medicine will present evidence that could at least exonerate H. pylori.

By no means are germs off the hook as a cause of coronary artery disease.

``I think this is a fascinating area of research,'' said Monty Bodenheimer, chief of cardiology at Long Island Jewish Medical Center in New Hyde Park, N.Y.

``At least two generations of doctors were trained to think of ulcers as being caused by too much (stomach) acid, and the drug companies went ahead and created these wonderful drugs for treating acid. But now we know differently and don't treat ulcers as too much acid; we treat the infection.''

While Bodenheimer does not think most cases of heart disease will turn out to be caused by microorganisms, infections could ultimately count as a significant risk factor in coronary artery disease, especially in cases in which patients have normal cholesterol profiles and considerable, inexplicable artery blockage.

``The cholesterol hypothesis doesn't explain all coronary artery disease,'' Bodenheimer added. ``It's a risk factor just like diabetes, hypertension and smoking.''

How a germ can trigger a blocked artery, one that will lead to angioplasty or bypass surgery, is still inconclusive.

British scientists from City Hospital in Birmingham, England, wrote recently in the medical journal The Lancet that it is still unknown whether chlamydia ``is an innocent bystander or whether it is a vicious assassin.''

The germ may get picked up by vacuum-cleaning cells of the immune system and inadvertently dropped in the arteries, along with other biological debris, causing blockage and inflammation. Or chlamydia might migrate from the lungs to the arteries, triggering a host of immune responses that rain through the artery, tearing away its lining, causing blood clots and spurring blockage and inflammation.

Meanwhile, doctors will continue fighting heart disease with an impressive array of weapons ranging from drugs and bypass surgery to angioplasty and lasers. And many are open to new ideas on weapons and theories.

``As recently as 15 years ago, there were a lot of doctors who weren't as convinced as they are now about the role of lipids (fats) in coronary artery disease,'' said Stacey Rosen, chief of the echocardiography laboratory at North Shore University Hospital in Manhasset, N.Y. ``Who knows what will be next?''