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Nonrandom occurrence of single-vessel coronary artery disease
Nonrandom Occurrence of Single-Vessel Coronary Artery Disease
ALAN FEIT, M.D., F.A.C.C. RAHMAN KHAN, M.D., F.A.C.C. NABIL EL-SHERIF, M.D., F.A.C.C. C. V. R;. REDDY, M.D., F.A.C.C. Brooklyn, New York
The location of obstructive coronary artery lesions In single-vessel disease is nonrandom. The circumflex coronary artery is protected relatlve to the right coronary artery. This may have Important implications regarding the causation of coronary obstructive lesions. The etiology of coronary artherosclerosis is not satisfactorily understood. No satisfactory model exists for human coronary artherosclerosis, and no satisfactory explanation has ever been made of why, in any person, obstructive lesions occur at the sites at which they are observed. If the site of an obstructive artherosclerotic lesion were, in any person predisposed to the disease, random, then we would expect the first occlusive lesion to be randomly located in either the right, left, or circumflex arteries with a frequency proportional to the relative size of these arteries. The development of subsequent occlusive lesions might no longer be a random event, possibly being influenced by the location of the first lesion and alterations in flow and myocardial resistance vessels. If the random occurrence hypothesis were true, one might expect a slightly higher frequency of single-vessel left anterior descending disease relative to either single-vessel right or singlevessel circumflex disease, but one would not expect any significant difference in the frequency of single-vessel circumflex and singlevessel right coronary artery disease, since in most cases these vessels are similar in size. PATIENTS AND METHODS To test this hypothesis, we reviewed 402 consecutive abnormal coronary angiographic results from 1981 to 1982. The patients were all men. In all, angiography was performed for currently accepted clinical indications. The results are summarized in Flgure 1. RESULTS
From the Cardiology Division, Department of Medicine, Brooklyn Veterans Administration Medical Center, and the State University of New York, Downstate Medical Center, Brooklyn, New York. Requests for reprints should be addressed to Dr. Alan Feit, Division of Cardiology, Brooklyn Veterans Administration Medical Center, 800 Poly Place, Brooklyn, New York 11209. Manuscript accepted January 19, 1984.
All angiographic findings of single-vessel disease were carefully reviewed. In only one of the seven cases of isolated circumflex disease was the right coronary artery nondominant; in all other cases of single-vessel circumflex or right coronary artery disease, the size of the arteries appeared equivalent. There were no unusual anatomic findings present in any of the 54 cases of single-vessel disease. The probability that the difference in frequency of single-vessel circumflex versus right coronary artery disease could be explained by chance is less than 0.81 percent (chi-square test). Clearly, the random assumption hypothesis is not valid for the 402 men who were studied.
October 1984
The American Journal of Medlclne
Volume 77
663
SINGLE-VESSEL
CORONARY
ARTERY DISEASE-FEIT
ET AL
7
3or %
4 25 v, F20Y$i
26 752
21
402
$5o> 2:
ioZ z IL 0
5-
7 402
CIRC TOTAL
RCA CASES
LAD 402
-I
Figure 1. Number of times single-vessei coronary artery disease was found in a particular artery. The difference in occurrence of circumflex coronaty artery (CRC) versus right coronary artery (RCA) single-vessel disease is significant at p = 0.008 1 (chi-square test). LAD = left anterior descending coronary artery.
COMMENTS
If isolated left or right coronary artery occlusive disease were inherently more symptomatic than isolated circumflex artery disease, then our selection process would invalidate our results. However, there is no reason to assume that isolated single-vessel disease should have variable symptomatic penetrance based on any factor other than relative vessel size. It appears that the potential significance of the nonrandom occurrence of single-vessel occlusive coronary artery disease has been overlooked. Frequently quoted references [l-3] on the distribution of coronary artherosclerotic lesions do not provide data on the relative frequencies of single-vessel disease, and Diethrich et
684
October 1984
The American Journal of Medicine
[4] reported, without comment, a frequency and distribution of single-vessel disease remarkably similar to our own. Our results can be viewed as showing either protection for the circumflex coronary artery or high risk for the right coronary artery. It is attractive to speculate that this difference is in some way related to the angle from which the circumflex arises from the left main coronary artery. The angle approximates 90 degrees, whereas the right coronary artery arises directly from the aorta. The left anterior descending artery, usually taking its origin as a continuation of the left main trunk, might also be thought of as arising directly from the aorta. Factors that might be contributing to the relative protection of the circumflex artery could be the role of turbulent versus laminar flow and/or the relationship of flow to the deposition of some blood-borne artherosclerotic agent. Characterizing the flow of a non-newtonian fluid such as blood, which contains active particles like platelets, is an extremely difficult problem; however, such attempts should continue. Nature has provided us with an experiment of potentially enormous import: Singlevessel obstructive coronary artery disease arises as a nonrandom event, with the right coronary artery being at higher risk relative to the circumflex. This may be a consequence of flow characteristics in the arteries. al
REFERENCES 1. 2.
3.
4.
Volume 77
Vlodaver Z, Edwards JE: Pathology of coronary atherosclerosis. Prog Cardiovasc Dis 1971; 14: 256-274. Pii 6, Zoll PM, Blumgart K, Freeman DC: Location of coronary arterial occlusions and then relation to the arterial pattern. Circulation 1903; 26: 35-41. White NK,Edwards JE, Dry TJ: The relationship of the degree of coronary atherosclerosis with age in man. Circulation 1953; 1: 645-654. Diethrich EB, Liddicoat JE, Kinard SA, Garret HE, Lewis JM, DeBakeY ME: Surgical significance of angiographic patterns in coronary arterial disease. Circulation 1967; 35 (suppl 1): 155-162.
ALAN FEIT, M.D., F.A.C.C. RAHMAN KHAN, M.D., F.A.C.C. NABIL EL-SHERIF, M.D., F.A.C.C. C. V. R;. REDDY, M.D., F.A.C.C. Brooklyn, New York
The location of obstructive coronary artery lesions In single-vessel disease is nonrandom. The circumflex coronary artery is protected relatlve to the right coronary artery. This may have Important implications regarding the causation of coronary obstructive lesions. The etiology of coronary artherosclerosis is not satisfactorily understood. No satisfactory model exists for human coronary artherosclerosis, and no satisfactory explanation has ever been made of why, in any person, obstructive lesions occur at the sites at which they are observed. If the site of an obstructive artherosclerotic lesion were, in any person predisposed to the disease, random, then we would expect the first occlusive lesion to be randomly located in either the right, left, or circumflex arteries with a frequency proportional to the relative size of these arteries. The development of subsequent occlusive lesions might no longer be a random event, possibly being influenced by the location of the first lesion and alterations in flow and myocardial resistance vessels. If the random occurrence hypothesis were true, one might expect a slightly higher frequency of single-vessel left anterior descending disease relative to either single-vessel right or singlevessel circumflex disease, but one would not expect any significant difference in the frequency of single-vessel circumflex and singlevessel right coronary artery disease, since in most cases these vessels are similar in size. PATIENTS AND METHODS To test this hypothesis, we reviewed 402 consecutive abnormal coronary angiographic results from 1981 to 1982. The patients were all men. In all, angiography was performed for currently accepted clinical indications. The results are summarized in Flgure 1. RESULTS
From the Cardiology Division, Department of Medicine, Brooklyn Veterans Administration Medical Center, and the State University of New York, Downstate Medical Center, Brooklyn, New York. Requests for reprints should be addressed to Dr. Alan Feit, Division of Cardiology, Brooklyn Veterans Administration Medical Center, 800 Poly Place, Brooklyn, New York 11209. Manuscript accepted January 19, 1984.
All angiographic findings of single-vessel disease were carefully reviewed. In only one of the seven cases of isolated circumflex disease was the right coronary artery nondominant; in all other cases of single-vessel circumflex or right coronary artery disease, the size of the arteries appeared equivalent. There were no unusual anatomic findings present in any of the 54 cases of single-vessel disease. The probability that the difference in frequency of single-vessel circumflex versus right coronary artery disease could be explained by chance is less than 0.81 percent (chi-square test). Clearly, the random assumption hypothesis is not valid for the 402 men who were studied.
October 1984
The American Journal of Medlclne
Volume 77
663
SINGLE-VESSEL
CORONARY
ARTERY DISEASE-FEIT
ET AL
7
3or %
4 25 v, F20Y$i
26 752
21
402
$5o> 2:
ioZ z IL 0
5-
7 402
CIRC TOTAL
RCA CASES
LAD 402
-I
Figure 1. Number of times single-vessei coronary artery disease was found in a particular artery. The difference in occurrence of circumflex coronaty artery (CRC) versus right coronary artery (RCA) single-vessel disease is significant at p = 0.008 1 (chi-square test). LAD = left anterior descending coronary artery.
COMMENTS
If isolated left or right coronary artery occlusive disease were inherently more symptomatic than isolated circumflex artery disease, then our selection process would invalidate our results. However, there is no reason to assume that isolated single-vessel disease should have variable symptomatic penetrance based on any factor other than relative vessel size. It appears that the potential significance of the nonrandom occurrence of single-vessel occlusive coronary artery disease has been overlooked. Frequently quoted references [l-3] on the distribution of coronary artherosclerotic lesions do not provide data on the relative frequencies of single-vessel disease, and Diethrich et
684
October 1984
The American Journal of Medicine
[4] reported, without comment, a frequency and distribution of single-vessel disease remarkably similar to our own. Our results can be viewed as showing either protection for the circumflex coronary artery or high risk for the right coronary artery. It is attractive to speculate that this difference is in some way related to the angle from which the circumflex arises from the left main coronary artery. The angle approximates 90 degrees, whereas the right coronary artery arises directly from the aorta. The left anterior descending artery, usually taking its origin as a continuation of the left main trunk, might also be thought of as arising directly from the aorta. Factors that might be contributing to the relative protection of the circumflex artery could be the role of turbulent versus laminar flow and/or the relationship of flow to the deposition of some blood-borne artherosclerotic agent. Characterizing the flow of a non-newtonian fluid such as blood, which contains active particles like platelets, is an extremely difficult problem; however, such attempts should continue. Nature has provided us with an experiment of potentially enormous import: Singlevessel obstructive coronary artery disease arises as a nonrandom event, with the right coronary artery being at higher risk relative to the circumflex. This may be a consequence of flow characteristics in the arteries. al
REFERENCES 1. 2.
3.
4.
Volume 77
Vlodaver Z, Edwards JE: Pathology of coronary atherosclerosis. Prog Cardiovasc Dis 1971; 14: 256-274. Pii 6, Zoll PM, Blumgart K, Freeman DC: Location of coronary arterial occlusions and then relation to the arterial pattern. Circulation 1903; 26: 35-41. White NK,Edwards JE, Dry TJ: The relationship of the degree of coronary atherosclerosis with age in man. Circulation 1953; 1: 645-654. Diethrich EB, Liddicoat JE, Kinard SA, Garret HE, Lewis JM, DeBakeY ME: Surgical significance of angiographic patterns in coronary arterial disease. Circulation 1967; 35 (suppl 1): 155-162.