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Prognosis of Normal Coronary Arteries
Abstract & Commentary
By Michael H. Crawford, MD, Professor of Medicine, and Chief of Clinical Cardiology, at the University of California, San Francisco. Dr. Crawford is on the speaker's bureau for Pfizer.
Source: Palmeri S, et al. Late Angiographic Follow-up in Adults with Angiographic Normal or Minimally Narrowed Coronary Arteries. Am J Cardiol 2007;99:1374-1377.
Up to 20% of patients undergoing coronary angiography have normal arteries or mild luminal irregularities. I am often asked how long a negative coronary angiogram is good for before you have to consider repeating the test because of symptoms suggesting ischemic heart disease? This study from the Robert Wood Johnson Medical School in New Jersey sheds some light on this question. The investigators retrospectively reviewed 733 patients who had cardiac catheterizations done in the late 1980s and found 115 who had a second study in the ensuing 15 years (mean 9 years). Their angiograms were mixed with those from 20 patients reported to have luminal irregularities and re-read blindly. Those with confounding conditions were excluded leaving a study population of 62 patients; 46 with normal arteries and 16 with lesions with < 30% narrowing. Most cardiac catheterizations were done for chest pain.
Results: Coronary artery disease (CAD) progression was more common in the luminal irregularity group (81%) vs the normal arteries (41%). Acute myocardial infarction developed in 11% of patients with normal arteries. Overall, patients with normal coronary arteries progressed by -2.6% luminal diameter per year. Those with luminal irregularities progressed at -6% per year. The authors concluded that in patients with angiographically normal or near normal coronary arteries, short-term prognosis is excellent, but late CAD manifestation can occur.
Prior studies that followed patients with normal coronary arteries found such low event rates that we were lead to believe that they had an excellent 10-year prognosis. So, I used to teach that the warranty on a normal coronary angiogram was 10 years. Of course, there are exceptions to everything, so patients with compelling chest pain symptoms and a prior normal angiogram, should still be taken seriously. This study sheds further light on the issue because of the availability of repeat angiograms. Not surprisingly, patients with mild luminal irregularities often (80%) showed progression at a rate of about 6% of diameter loss per year. At this rate you could go from 30% to over 50% stenosis in less than 3 years. These patients have atherosclerosis and should be medically treated aggressively. In those with normal arteries by angiography progression of any underlying CAD is slower, so to get from zero to 50% narrowing could take 15-20 years. So, if the angiogram is stone cold normal the old impression that they are good for at least 10 years is probably still true. However, myocardial infarction often occurs because of rupture of a non-flow limiting plaque (<50% stenosis). In this study 11% of those with normal coronary arteries had a subsequent myocardial infarction. Thus, those with risk factors for CAD should have them addressed, since de novo or progression of angiographically silent CAD can occur late.