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Strategy for treatment of left main coronary artery disease—II
LETTERS
TO THE EDITOR
STRATEGY FOR TREATMENT OF LEFT MAIN CORONARY ARTERY DISEASE-l One issue raised by Epstein et al.’ needs further comment, namely, the question of left main coronary artery disease, which was presented in somewhat overly pessimistic terms. In the emotionally charged controversy concerning indications for invasive evaluation and surgical treatment of patients with coronary artery disease, the appearance of data showing that a subset of such patients clearly survive longer after bypass surgery was hailed with great enthusiasm. Left main coronary artery disease became a symbol of the deadliness of the disease, a red flag, a license used to justify widereaching case-finding programs that involve invasive evaluation of many asymptomatic subjects. Yet, a dispassionate review of the available information on this disease leads one to conclude that this obsessive attitude is premature and that more points need classification. 1. Left main coronary arterial stenosis has a low incidence rate,2 occurring in only 5 percent of patients with coronary artery disease undergoing coronary arteriography. In most of these patients, the lesion is combined with severe involvement of other branches, so that only 0.2 percent of patients have an isolated lesion. Thus, in the majority of cases the contribution of a left main lesion is not known; it may merely be a marker for the more serious subset of three vessel coronary artery disease. Evaluation of the prognosis of stenosis of the left main coronary artery will be available only after an analysis of isolated left main coronary disease. 2. Left main coronary artery disease involves a wide range of arterial narrowing (from 50 to 99 percent as estimated with arteriography). There is increasing evidence that only the most severe degree of stenosis is associated with a poor prognosis in patients receiving medical therapy. In other words, there is a large subset of patients in whom this lesion is basically benign.3 3. The contribution of collateral circulation is often ignored or minimized. Effective collateral channels usually develop from the right coronary system, given time, as shown by a number of cases of total occlusion of the main left coronary artery associated with survival and not necessarily serious clinical consequences.4 4. In the great majority of cases of significant left main coronary arterial stenosis the patients are severely symptomatic, usually showing unstable angina pectoris. It is not unreasonable to assume that when a left main coronary arterial stenotic lesion is found in an asymptomatic or mildly symptomatic patient, the probability is high that the lesion has not yet reached the critical stage. It follows that a clinically “silent” left main lesion will most likely become “manifest” by clinical symptoms when it progresses to the critical stage. Logically, it is necessary to answer the fundamental question: How often does a critical life-threatening left main coronary arterial lesion exist without causing symptoms? The only evidence that this situation does exist is provided by instances of sudden death occurring without warning in subjects with a silent main left coronary arterial lesion. Anecdotal quotation of such cases is not enough; actual figures are necessary, proving that patients with milder degrees of this lesion are more prone to unanticipated sudden death than are random patients with coronary artery disease. In light of the
relative rarity of severe left main coronary arterial lesions and given the assumption that only a very small number of patients with a left main lesion are at risk of dying before warning symptoms develop, a wide search for patients with a silent left main lesion is neither cost effective nor beneficial, considering the unwarranted anxiety it might arouse in a wide segment of a healthy or asymptomatic population. Arthur Seizer, MD, FACC Division of Cardiology Presbyterian Hospital of Pacific Medical Center San Francisco, California References 1.
Epstein SE, Kenf KY. Goldsl~b RE, Scfef JS, Rosfng DR. Strategy for evaluation and surgical treatment of the asymptomatic and mildly symptomatic patients with coronary artery disease. Am J Cardiol 1979;45:1015-25. 2. Stone Ptf, Goldschfager N. Left main coronary artery disease: review and appraisal. Cardiovasc Med 1979;4:165-78. 3. Conby NJ, Ely RL, Klsslo J, Lee KL, McNee~ K, Rosatl RA. The prognostic spectrum of left main stenosis. Circulation 1978;57:947-52. Gmaman W, MEUICIBJE, Cohen MV, Saltaxe HA, L&n DC. Total occlusion 4. wSl of left main cwnary artery: a clinical hemodynamic and angiogfaphic profile. Am J Med 1978;64:3-9.
STRATEGY FOR TREATMENT OF LEFT MAIN CORONARY ARTERY DISEASE-II
Because one of the main purposes of the article by Epstein et al. is to emphasize the high cost of screening patients, I find their thinking inconsistent when they recommend cardiac catheterization for all mildly symptomatic patients and those with previous infarctions merely for the purpose of identifying the patient with disease of the left main coronary artery. Surely they are aware that significant disease of this artery is rarely present in the absence of marked S-T segment depression in the exercise electrocardiogram; in addition, it is almost always associated with advanced left ventricular dysfunction. Thus, the vast majority of patients with this disease are quite symptomatic and can readily be identified by a careful history and physical examination in conjunction with an exercise test and perhaps one or more other noninvasive procedures when necessary. Furthermore, as a group they respond poorly to medication. Too often cardiac catheterization is carried out after minimal examination and little or no treatment for the purpose of “excluding left main disease.” The approach recommended by Epstein et al. tends to support such practices and helps maintain the high cost of medical care. It would make much more sense to follow up patients with mild symptoms in the usual clinical manner and reserve invasive studies for those who show steady progression of their symptoms. Howard H. Wayne, MD, FACC San Diego County Diagnostic Heart Center San Diego, California
REPLY
Selzer’s and Wayne’s letters expressing concern about the issue of left main coronary artery disease are timely and appropriate. They also provide us with the opportunity of reemphasizing our own approach to this lesion, which is
September 1980
The American Journal of CARDIDLDDY
Volume 48
517
TO THE EDITOR
STRATEGY FOR TREATMENT OF LEFT MAIN CORONARY ARTERY DISEASE-l One issue raised by Epstein et al.’ needs further comment, namely, the question of left main coronary artery disease, which was presented in somewhat overly pessimistic terms. In the emotionally charged controversy concerning indications for invasive evaluation and surgical treatment of patients with coronary artery disease, the appearance of data showing that a subset of such patients clearly survive longer after bypass surgery was hailed with great enthusiasm. Left main coronary artery disease became a symbol of the deadliness of the disease, a red flag, a license used to justify widereaching case-finding programs that involve invasive evaluation of many asymptomatic subjects. Yet, a dispassionate review of the available information on this disease leads one to conclude that this obsessive attitude is premature and that more points need classification. 1. Left main coronary arterial stenosis has a low incidence rate,2 occurring in only 5 percent of patients with coronary artery disease undergoing coronary arteriography. In most of these patients, the lesion is combined with severe involvement of other branches, so that only 0.2 percent of patients have an isolated lesion. Thus, in the majority of cases the contribution of a left main lesion is not known; it may merely be a marker for the more serious subset of three vessel coronary artery disease. Evaluation of the prognosis of stenosis of the left main coronary artery will be available only after an analysis of isolated left main coronary disease. 2. Left main coronary artery disease involves a wide range of arterial narrowing (from 50 to 99 percent as estimated with arteriography). There is increasing evidence that only the most severe degree of stenosis is associated with a poor prognosis in patients receiving medical therapy. In other words, there is a large subset of patients in whom this lesion is basically benign.3 3. The contribution of collateral circulation is often ignored or minimized. Effective collateral channels usually develop from the right coronary system, given time, as shown by a number of cases of total occlusion of the main left coronary artery associated with survival and not necessarily serious clinical consequences.4 4. In the great majority of cases of significant left main coronary arterial stenosis the patients are severely symptomatic, usually showing unstable angina pectoris. It is not unreasonable to assume that when a left main coronary arterial stenotic lesion is found in an asymptomatic or mildly symptomatic patient, the probability is high that the lesion has not yet reached the critical stage. It follows that a clinically “silent” left main lesion will most likely become “manifest” by clinical symptoms when it progresses to the critical stage. Logically, it is necessary to answer the fundamental question: How often does a critical life-threatening left main coronary arterial lesion exist without causing symptoms? The only evidence that this situation does exist is provided by instances of sudden death occurring without warning in subjects with a silent main left coronary arterial lesion. Anecdotal quotation of such cases is not enough; actual figures are necessary, proving that patients with milder degrees of this lesion are more prone to unanticipated sudden death than are random patients with coronary artery disease. In light of the
relative rarity of severe left main coronary arterial lesions and given the assumption that only a very small number of patients with a left main lesion are at risk of dying before warning symptoms develop, a wide search for patients with a silent left main lesion is neither cost effective nor beneficial, considering the unwarranted anxiety it might arouse in a wide segment of a healthy or asymptomatic population. Arthur Seizer, MD, FACC Division of Cardiology Presbyterian Hospital of Pacific Medical Center San Francisco, California References 1.
Epstein SE, Kenf KY. Goldsl~b RE, Scfef JS, Rosfng DR. Strategy for evaluation and surgical treatment of the asymptomatic and mildly symptomatic patients with coronary artery disease. Am J Cardiol 1979;45:1015-25. 2. Stone Ptf, Goldschfager N. Left main coronary artery disease: review and appraisal. Cardiovasc Med 1979;4:165-78. 3. Conby NJ, Ely RL, Klsslo J, Lee KL, McNee~ K, Rosatl RA. The prognostic spectrum of left main stenosis. Circulation 1978;57:947-52. Gmaman W, MEUICIBJE, Cohen MV, Saltaxe HA, L&n DC. Total occlusion 4. wSl of left main cwnary artery: a clinical hemodynamic and angiogfaphic profile. Am J Med 1978;64:3-9.
STRATEGY FOR TREATMENT OF LEFT MAIN CORONARY ARTERY DISEASE-II
Because one of the main purposes of the article by Epstein et al. is to emphasize the high cost of screening patients, I find their thinking inconsistent when they recommend cardiac catheterization for all mildly symptomatic patients and those with previous infarctions merely for the purpose of identifying the patient with disease of the left main coronary artery. Surely they are aware that significant disease of this artery is rarely present in the absence of marked S-T segment depression in the exercise electrocardiogram; in addition, it is almost always associated with advanced left ventricular dysfunction. Thus, the vast majority of patients with this disease are quite symptomatic and can readily be identified by a careful history and physical examination in conjunction with an exercise test and perhaps one or more other noninvasive procedures when necessary. Furthermore, as a group they respond poorly to medication. Too often cardiac catheterization is carried out after minimal examination and little or no treatment for the purpose of “excluding left main disease.” The approach recommended by Epstein et al. tends to support such practices and helps maintain the high cost of medical care. It would make much more sense to follow up patients with mild symptoms in the usual clinical manner and reserve invasive studies for those who show steady progression of their symptoms. Howard H. Wayne, MD, FACC San Diego County Diagnostic Heart Center San Diego, California
REPLY
Selzer’s and Wayne’s letters expressing concern about the issue of left main coronary artery disease are timely and appropriate. They also provide us with the opportunity of reemphasizing our own approach to this lesion, which is
September 1980
The American Journal of CARDIDLDDY
Volume 48
517