For Release: February 15, 2000
Contact: Kimberly Lynch, ACCP
(847) 498-8341
[email protected]
OUTLOOK GOOD FOR HEART ATTACK PATIENTS WHO HAVE NORMAL ARTERIES
The outlook for individuals who suffer heart attacks despite having normal coronary arteries is excellent according to a Swiss study reported today in CHEST, the peer-reviewed journal of the American College of Chest Physicians.
Somewhere between one and 12 percent of individuals suffering myocardial infarctions are deemed to have normal coronary arteries as determined by angiography, an x-ray visualization of the internal anatomy of the heart and blood vessels after injection of a dye. The disease is called MINC which stands for myocardial infarction with angiographically normal coronary arteries.
The cause of the disease is still unknown although coronary or blood vessel spasms, thrombosis, platelet dysfunction, Raynaud's phenomenon, and migraine headaches all have been implicated. Recently, an inflammatory response possibly due to chlamydial or other bacterial or viral infections have been proposed as a possible mechanism for MINC. There have been little data on the prognosis for those with the condition.
Investigators in Switzerland conducted a study to assess the prognosis of MINC patients and compare their clinical characteristics with patients with coronary artery disease. From a pool of 2,100 individuals who had suffered myocardial infarctions, 25 were identified as having normal coronary arteries. Of these, 21, who had a classical history of myocardial infarction, definite ECG changes, and a diagnostic increase in myocardial enzyme activity, were selected for the study group and compared against a control group of 21 patients with similar age and sex characteristics who had a heart attack due to coronary artery disease (CAD). All study participants filled out questionnaires to determine the prevalence of migraine and Raynaud's phenonemon. Also measured or reported were a number of CAD risk factors such as Body Mass Index (BMI). blood pressure, cholesterol, diabetes, family history, smoking history, and the existence of angina pectoris prior to their heart attack.
In addition, blood tests to determine variables associated with thrombophilia (tendency to clot), lipids, and antibodies against Chalmydia pneumoniae, cytomegalovirus (CMV), and Helicobacter pylori were conducted. Researchers found that MINC patients had less angina pectoris (chest pain) before the heart attack than did CAD patients but had more febrile infections prior to the attack.
The scores for migraine headaches were significantly higher in the MINC patients. MINC patients had fewer histories of high blood cholesterol and high blood pressure but there were no significant differences concerning other risk factors such as family history, hormonal substitution, and diabetes. MINC patients had higher levels of HDL (the "good" cholesterol) but there were no significant differences in LDL (the "bad" cholesterol) measurements. No electrocardiogram or clinical evidence for coronary spasm was provoked in either group by hyperventilation. Followup patients with CAD had a higher rate of rehospitalization and repeated coronary angiography.
Peter Ammann, M.D., of the Department of Cardiology, Triemli Hospital in Zurich, said "an interesting finding in our study was the significantly higher numberof MINC patients with febrile infection, mainly of the upper airways, within 2 weeks prior to infarction." He added that this finding raises new questions regarding the cause of heart attacks in some MINC patients. He raised the possibility of a coronary thrombosis and/or the rupture of plaque that could have been triggered by systemic inflammation itself or by specific infective components. He noted that recent studies have suggested a possible association of C pneumoniae, CMV, and H pylori in the acute coronary syndromes of patients with CAD. He said: "Our findings of higher incidence of IgA titers against C pneumoniae, as compared to healthy blood donors, would be compatible with an inflammatory component of acute myocardial infarction.
It is furthermore tempting to speculate," he said, "that the higher incidence of febrile infection in our MINC patients might be causally related to their coronary event. However," he added, "we found no difference in antibody titers to CMV and H pylori between MINC and CAD patients. Nevertheless," he said, "no repeat titer determinations were done and a potential difference with regard to infections with these agents cannot be dismissed."
Dr. Ammann and colleagues concluded that the prognosis for MINC patients is excellent. They said: "During followup at a mean of 5.3 years after infarction, MINC patients had a very good exercise capacity. No one had a major adverse cardiac event or required repeat coronary angiography."
CHEST is published by the American College of Chest Physicians which represents 15,000 members who provide clinical, respiratory, and cardiothoracic patient care in the U.S. and throughout the world. ___________________________________________________________
Reporters may wish to contact Kimberly Lynch of the ACCP at (847) 498-8341 for a full copy of this article. She can also be reached by fax at (847) 498-5460 or by email at [email protected]. Dr. Ammann can be reached by phone at 41-1-466-111 or by email at [email protected].
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