Left main coronary artery stenosis: state-of-the-art

Patients with stenosis of the left main coronary artery present difficult challenges. The risks associated with this lesion have been known since the early days of angiography when patients were found to have increased mortality during follow-up. This information led to the general guidelines that surgical revascularization should be considered the treatment of choice in patients with significant left main coronary artery stenosis. Current advances in invasive cardiology have brought important information to the field. Intravascular ultrasound is now used routinely to evaluate angiographically indeterminate lesions with criteria now set forward as to what constitutes an indication for revascularization. Stents have even further dramatically changed the landscape. There are substantial issues, however, that need to addressed. These include the following: (1) the effect of specific lesion location on outcome - it is known that patients with distal bifurcation left main disease have worse outcome; (2) the potential for subacute thrombosis of the left main coronary artery; (3) the impact of left ventricular function and patient comorbidities irrespective of the degree and location of left main coronary artery stenosis; and (4) the risk-benefit ratio of stenting versus coronary artery bypass graft surgery. These issues are currently being addressed in two seminally important trials including the SYNTAX trial, which randomizes patients with left main and/or three-vessel disease to either coronary artery bypass graft surgery or a TAXUS drug-eluting stent. This trial is in the final stages of patient recruitment and will have important implications for the field. The other trial is the COMBAT trial, which is focused exclusively on left main coronary artery stenosis and randomizes patients with left main coronary artery disease either to a Sirolimus-eluting stent (Cypher, Johnson and Johnson Cordis, USA) or to coronary artery bypass graft surgery. The field of left main coronary artery disease continues to expand in terms of the evidence available for optimal patient evaluation and selection of treatment modalities.     

Left main coronary artery stenosis in young patients.

Among 1,041 patients less than 45 years old who underwent coronary arteriography from 1972 to 1977, left main coronary stenosis greater than or equal to 50 percent was present in 31 men (3.4 percent) and in 10 women (7.2 percent, P less than 0.05). The degree of stenosis did not correlate with the duration of symptoms, the severity of angina, the presence of a previous myocardial infarction, nor with the number of risk factors. The clinical and angiographic features in young men did not seem to differ from those described in unselected populations; however, in young women, left main coronary stenosis was often an isolated lesion associated with a short duration of symptoms, a high prevalence of hypertension, no previous myocardial infarction, and a normal ventriculogram, suggesting the possibility that a different pathophysiologic mechanism might be involved. Two deaths occurred at angiography (4.9 percent). Thirty patients underwent coronary artery bypass surgery, with one operative death and one late death; good functional results were obtained, and 21 out of 28 survivors (75 percent) were asymptomatic after a mean follow-up of 29 months.     

Left main coronary artery stenosis.

Between 1 January, 1989, and 28 April, 1990, a total of 888 selective coronary arteriographies were performed at the Institute for Clinical and Experimental Medicine in Prague. Of that number, 58 findings were assessed as at least 50% stenosis of the left main coronary artery (LCA). Having applied exclusion criteria, 50 patients (i.e., 5.63% of all those examined) were entered into a retrospective study. They were 45 men (90.0%) and 5 women (10.0%) with significant cumulation of risk factors for IHD; more than half on them had a history of coronary event. The patients had marked symptomatology--NYHA Class III and higher angina pectoris was present in 96%, a low tolerance of exercise was found in 26 patients undergoing ergometry (average workload of 13 kJ and heart rate of 111/min); exercise testing was invariably evaluated as positive. Coronary angiography regularly revealed multiple coronary artery lesions; the right coronary artery was also involved in 90%; a collateral circulation was present in as little as 34%. The localization of coronary stenoses and the mostly preserved left ventricular mechanical function allowed operative management of IHD in 84% of cases. In the group of patients undergoing surgery, hospital mortality was 4.8%. On long-term follow-up (mean 6.2 months) of the group of patients operated on, 59.9% were free of problem, 31% had NYHA Class II angina pectoris, and there was no improvement at all in one patient only (2.4%). In the group provided conservative therapy (not operated on primarily for severe left ventricular dysfunction), one patient died of recurrent myocardial infarction and cardiogenic shock, 2 have NYHA Class IV angina pectoris, and the remaining subjects continue experiencing NYHA Class III problems.     

Left main coronary artery stenosis: angiographic determination

Reliability of angiographic assessment of the left main coronary artery segment was evaluated by review of 106 coronary cineangiograms from the Coronary Artery Surgery Study. The films were interpreted by three groups of angiographers: those at a clinical site, those at a quality control site, and those on a study census panel. Among the readings of these three groups, there was 41% to 59% agreement on the severity of the lesion, with 80% agreement on whether the lesion was greater or less than 50%. The severity of lesion, its location, or presence of ectasia or calcium did not affect the discrepancy rate, whereas segments that were unusually short, diffusely diseased, or obscured by overlapping vessels were especially difficult to interpret.     

Left main coronary artery stenosis and progression of coronary artery atherosclerosis after angioplasty and stenting in patients directed to coronary artery bypass surgery

Recent investigations demonstrated appearance of left main coronary artery stenosis after PTCA. We performed a retrospective study of specific characteristics of development of coronary lesions after percutaneous coronary interventions (PCI) in patients subjected to coronary artery bypass grafting (CABG) because of angina recurrence after PCI. Data of 150 patients operated because of angina recurrence after PCI were analyzed. The recurrence of angina in 93% of cases was associated with development of significant stenoses in previously intact segments of coronary arteries, but not with restenosis or occlusion of the stented segment. The recurrence of symptoms occurred in 1 year after coronary stenting in 54% of patients. In 19 patients rapid development of a novel left main coronary artery stenosis was observed. Some characteristics of this group (the use of Back-up, XB, AL-catheters, repetitive PCI, manipulations in more than 2 coronary segments, stenting of bifurcations with 2 stents, use of kissing-balloons, small diameter of left coronary artery, and concomitant diabetes) significantly differed from those of the main group. In all patients CABG was successful.     

Left main coronary artery stenosis following mediastinal irradiation

The association of mediastinal radiation therapy and coronary artery disease has been documented over the past three decades. This report describes a case of left main coronary artery stenosis eight years after radiation therapy in a 27-year-old woman. The patient was a young woman with no risk factors for coronary artery disease who had development of new-onset angina at rest. At coronary arteriography, the patient was found to have a tight ostial left main stenosis. The association of mediastinal radiation therapy with fixed and vasospastic coronary artery disease is reviewed. With many patients treated by radiation therapy now surviving their thoracic malignancies, an enlarging young population may be susceptible to the early development of ischemic heart disease.     

Left main coronary artery stenosis: the influence of aortocoronary bypass surgery on survival.

A retrospective study was carried out in 114 unoperated and 197 operated patients having left main coronary artery (LMCA) stenosis greater than or equal to 50%. Including the operative mortality of 9.1%, survival at seven years was significantly greater following pure aortocoronary bypass graft surgery, 77.5% as compared to 48.5% for the unoperated patients (P less than 0.01). The surgical mortality was significantly less during the last five years (1972-1976), 6.2% as compared to 17% during 1969-1971 (P less than 0.025). The three year survival in patients operated since 1972 was 90.2% as compared to 60.4% for unoperated patients. Survival remained significantly higher in the operated patients when studied as subsets on the basis of the severity of the LMCA stenosis (less than 70% as opposed to greater than or equal to 70%), and on the extent of associated obstructive disease of major coronary arteries (0-1 versus 2-3 arteries). It was significantly higher, however, only in operated patients with associated stenosis greater than or equal to 70% of the right coronary artery. Survival was higher following surgery only when the ejection fraction was at least 0.45, or the left ventricular end-diastolic pressure below 20 mm Hg.     

Left main coronary artery stenosis: a possible complication of transluminal coronary angioplasty

Coronary transluminal angioplasty is a new alternative modality for the treatment of specific lesions of coronary artery disease. Although numerous complications have been recognized, this represents the first report of development of a severe left main coronary artery stenosis following left anterior descending artery angioplasty.     

Left main coronary artery dissection during cardiac catheterization.

A 70-year-old man with a downward sloping origin of the left main coronary artery developed left main dissection at coronary angiography and died despite emergency coronary by-pass surgery. Autopsy showed that the left main coronary artery had an acute angle take off and dissection had originated at the junction of the superior wall of the left main and the aorta. The combination of left main stenosis secondary to dissection and severe right coronary atherosclerosis had caused circumferential subendocardial left ventricular infarction. The left main coronary artery had mild atherosclerosis and lacked cystic medial necrosis. An angulated left main coronary artery may be a risk factor for dissection at angiography.     

Pericatheterization risk factors in left main coronary artery stenosis

Patients with left main (LM) coronary artery disease (CAD) have an unexplained high incidence of complications during diagnostic cardiac catheterization. This study identifies pericatheterization risk factors for major complications in patients with LM CAD (stenosis at least 50%). Complications were defined as ventricular fibrillation not related temporally to coronary injection, persistent angina, acute myocardial infarction, profound hypotension and death during or within 24 hours of catheterization. One hundred seven consecutive cases of LM CAD (11 with complications and 96 without) were reviewed with respect to variables potentially related to complications. Patients who had angina in the 24 hours before catheterization were at increased risk. Four of 13 patients with angina (31%) and 7 of 94 (7%) without angina had complications (p less than 0.05). Distance from the catheter tip to the lesion also was related to complications (9 of 38 [24%] with tip 6.0 mm or less from lesion and 2 of 65 [3%] with tip more than 6.0 mm from lesion, p less than 0.05). No relaxation was found between complications and New York Heart Association functional class, technique (femoral vs brachial), performance of ventriculography, number of coronary injections, amount of contrast injected, severity of LM stenosis, number of major arteries with 75% or more diameter stenosis, mean arterial pressure, left ventricular end-diastolic pressure and left ventricular ejection fraction.     

Left main coronary artery ostial stenosis: the role of transoesophageal echocardiography

Transoesophageal echocardiography (TEE) using colour flow Doppler and intracoronary flow velocity measurements by pulsed Doppler may be helpful in detecting coronary artery disease. We present a case of a middle-aged man in whom left main ostial stenosis was detected by TEE after two non-diagnostic coronary angiographies. The main message of our case is that TEE was performed and was diagnostic after two non-diagnostic coronary angiographies. If ischaemia is confirmed TEE should be performed in cases of negative coronary angiographies to rule out left main ostial stenosis.     

Left main coronary artery stenosis associated with extremely long fusiform aneurysm

Coronary artery aneurysm is defined as coronary dilatation, which exceeds the diameter of normal adjacent segment or the diameter of the patient's largest coronary vessel by 1.5 times [Syed M, Lesch M: Coronary artery aneurysms: a review. Prog Cardiovasc Dis 1997; 40:77-10 84 [1]]. Most studies show an incidence of 1% to 2% [Barettella MB, Bott-Silverman C. Coronary artery aneurysm: an unusual case report and a review of the literature. Cathet Cardiovasc Diagn 1993; 29:57-61 [2]]. Left main coronary aneurysms (LMCA) are even more rare; in a study by involving 22,000 coronary angiograms an occurrence rate of 0.1% has been found [Topaz O, DiSciascio G, Cowley MJ, Goudreau E, Soffer A, Nath A et al. Angiographic features of left main coronary artery aneurysms. Am J Cardiol 1991; 67:1139-1142 [3]]. The majority of patients present with ischemic symptoms secondary to the coexisting atherosclerotic lesions and most of the coronary aneurysms are incidentally diagnosed by coronary angiography. This report details the exceptional case of a 62-year-old patient with "unusually long fusiform" aneurysm of the left main coronary artery associated with critical left main coronary artery distal stenosis involving the ostia of left anterior descending and left circumflex coronary artery. With this case the possible anatomic determinants of the type, location, and mechanism of aneurysm formation were also discussed.     

Left main coronary artery atresia

We present a report of an extremely rare case of left main coronary artery atresia in a 33 year-old male with severe symptoms of angina pectoris and dyspnoea. During coronary angiography, the left coronary artery (LCA) ostium could not be catheterised. The right coronary artery (RCA) was dilated, and the LCA was filling retrogradely via collateral vessels. The diagnosis was confirmed by multislice computed tomography. Due to severe symptoms and the high risk of sudden cardiac death, the patient was referred for coronary artery revascularisation. The left internal mammary artery was anastomosed to the left anterior descending artery. The operation and subsequent 24 months follow-up were uneventful.     

Left main coronary artery aneurysm

Left main coronary artery aneurysm is rare finding at coronary angiography. We report a case of a large left main coronary artery aneurysm in a 59-year-old male who had cardiac catheterization for effort angina and inducible myocardial ischemia.     

Left main coronary artery aneurysm

Left main coronary artery aneurysms (LMCA) are usually asymptomatic and are rarely encountered during coronary angiography. The most serious complications include coronary thrombosis, acute myocardial infarction and sudden death. Atherosclerosis is the most common cause, although several autoimmune diseases and congenital abnormalities have been associated with the presence of coronary aneurysms. The case of a symptom-free 63-year-old man with a giant LMCA and severely ectatic coronary arteries is presented.     

Left main coronary artery occlusion

Patients with complete occlusion of the left main coronary artery are candidates for massive myocardial infarction and sudden death and are thought to have a uniformly poor prognosis. Complete occlusion of the left main coronary artery was identified in 2 male patients among 2,546 patients undergoing cardiac catheterization over a period of 14.5 years in our institution. Both patients had angina pectoris. Left ventricular end-diastolic pressure was markedly elevated in one, and the ejection fraction was moderately to markedly reduced in both. Significant collateral flow to the left coronary system from the right coronary artery was present in both patients. Our study supports previous reports that left main coronary artery occlusion is rarely encountered during cardiac catheterization.