Thanks in large part to recent efforts spearheaded by the American Heart Association, the public is finally awakening to the fact that heart disease is as big a problem in women as it is in men. Furthermore, many are now aware that women with some types of heart disease - particularly, coronary artery disease (CAD) - may not have the same symptoms as men, and for this reason the correct diagnosis in women is often missed or delayed.
What is less well known, because researchers are only now recognizing the problem themselves, is that in some women the CAD itself may develop quite differently than in men, and that these differences may render the usual diagnostic tests relatively useless. This "new" type of CAD has been so recently described that many cardiologists are still unaware of it, and it has not been given a formal name. For the purposes of this discussion we will call it "female-pattern" CAD.
Typically, CAD occurs when part of the smooth, elastic lining inside a coronary artery (the arteries that supply blood to the heart muscle) develops atherosclerosis. With atherosclerosis, the artery's lining becomes hardened, stiffened, and swollen with all sorts of "grunge" - including calcium deposits, fatty deposits, and abnormal inflammatory cells - to form a plaque. Plaques can be thought of as large "pimples" that protrude into the channel of an artery, causing a partial obstruction to blood flow. Patients with CAD might have just one or two plaques, or might have dozens distributed throughout their coronary arteries.
In women with female-pattern CAD, the process of atherosclerosis does not form localized plaques; that is, the localized blockages are absent. Instead, the plaques in these women are more diffuse, involving to some degree the entire circumference of the artery. These women, in response to atherosclerosis, "remodel" the entire artery so that the lining of the artery becomes thickened throughout, making the plaques flush with the wall of the artery. ( This kind of arterial remodeling is apparently a unique capability of women, since they do something quite similar during pregnancy. ) So, there are no localized "pimples" producing discrete blockages in female-pattern CAD; the entire artery is just narrower. On cardiac catheterization their coronary arteries appear smooth-walled and normal, though they may look "small" in diameter.
Female-pattern CAD can and does cause acute heart attacks, since these plaques can erode and rupture, causing the blood to clot within the artery and producing sudden arterial blockage. (This erosion and clotting is what causes heart attacks in men, too.) Then, if the clot is successfully dissolved with clot-busting drugs, the subsequent heart catheterization usually shows "normal" coronary arteries, thus confounding the cardiologist. The prognosis with female-pattern CAD is thought to be better than with typical CAD, but this is nota benign condition.
The diagnosis of female-pattern CAD can be made definitively with a relatively new technique called intravascular ultrasound (IVUS) imaging. IVUS (which is not available in most hospitals) requires inserting a specialized catheter into the coronary artery that uses ultrasound (i.e., echocardiography) to visualize the wall of the artery from within. The diffuse plaques of the remodeled artery can be identified in this way. In a recent study, more than half the women who had angina with "normal" coronary arteries had plaques identified using IVUS. Female-pattern CAD should be suspected in any woman who has had angina or an MI, who has risk factors for CAD, but who has "normal" coronary arteries on cardiac catheterization.
Because the narrowing of the coronary arteries in female-pattern CAD is diffuse, therapies aimed at relieving localized obstructions - such as angioplasty, stents, and bypass surgery - do not apply. Instead, therapy must be medical. Optimal treatment for this condition has yet to be defined, but a multi-pronged approach seems the best at this time, and should include aggressive risk factor modification, therapy to reduce the risk of clotting (aspirin,) and drugs to protect the heart muscle itself (beta blockers and possibly ACE inhibitors). Researchers have now focused their attention on female-pattern CAD, and a better understanding of this condition and its treatment is very likely in the foreseeable future.
In the meantime, women and their doctors should be aware that in the setting of angina-like chest pain, seeing "normal" coronary arteries does not rule out a cardiac problem. Indeed, there are now three conditions that need to be considered (aside from the usual suspect - gastric reflux.) In addition to cardiac syndrome X and coronary artery spasm, we must now worry about female-pattern CAD.
