Left main coronary artery stenosis: clinical spectrum, pathophysiology, and management

High Risk Percutaneous Coronary Intervention of Left Main Bifurcation Stenosis in a Peritoneal Dialysis Patient

Complex coronary artery disease is the leading cause of death in patients with end-stage renal disease. We report a case of a patient on peritoneal dialysis, preloaded with Prasugrel and acetylsalicylic acid as а potent dual antiplatelet therapy (DAPT). The patient underwent a high-risk percutaneous coronary intervention (PCI) due to bifurcation stenosis of the left main stem branch. A "double kiss crush" bifurcation stenting technique was performed. This case provides additional data about the treatment of this group of patients, a group that is often excluded from randomized control trials, but is frequently encountered in cardiovascular practice. Furthermore, it helps to advance PCI treatment along with exploring the safety of potent DAPT in a group that is susceptible to both ischemia and bleeding, thus presenting a great challenge in the decision for treatment.

NOBLE and EXCEL: The debate for excellence in dealing with left main stenosis

Left main coronary artery (LMCA) disease is associated with increased morbidity and mortality. Coronary artery bypass grafting surgery (CABG) has always been the standard revascularization strategy for this group of patients. However, with the recent developments in stents design and medical therapy over the past decade, several trials have been designed to evaluate the safety and efficacy of percutaneous coronary intervention (PCI) as an alternative to CABG surgery in patients with LMCA disease. Recently, the results of two major trials, EXCEL and NOBLE, comparing CABG versus PCI in this patient population have been released. In fact, the results of both trials might appear contradictory at first glance. While the EXCEL trial showed that PCI was non-inferior to CABG surgery, the NOBLE trial suggested that CABG surgery is a better option. In the following review, we will discuss some of the similarities and contrasts between these two trials and conclude with lessons to be learned to our daily practice.

Impact of plaque burden in the left main coronary artery determined by intravascular ultrasound on cardiovascular events in a Japanese population undergoing percutaneous coronary intervention

The left main coronary artery (LMCA) is a particularly important target of atherosclerotic plaque accumulation. The aim of this study was to investigate the connection between subclinical plaque burden in the LMCA measured by intravascular ultrasound and future cardiovascular events. Two hundred eighteen consecutive patients underwent percutaneous coronary intervention for the left anterior descending coronary artery or the left circumflex coronary artery under intravascular ultrasound guidance. Plaque burden in the LMCA was analyzed for these patients, and major adverse cardiac events were also evaluated. Data were analyzed by grouping the patients into tertiles according to plaque burden values; tertile 1, <32% area stenosis; tertile 2, 32% to 45% area stenosis; and tertile 3, >45% area stenosis. During a 3-year follow-up period (average 16.1 months), 12% of tertile 1, 18% of tertile 2, and 40% of tertile 3 experienced major adverse cardiac events, mostly due to repeat revascularization (p <0.001). On Cox multivariate analysis, plaque burden in the LMCA (per percentage) detected by intravascular ultrasound remained an independent significant predictor of major adverse cardiac events (hazard ratio 1.04, 95% confidence interval 1.02 to 1.07) and future revascularization (hazard ratio 1.05, 95% confidence interval 1.02 to 1.07) (p <0.001). In conclusion, plaque burden in the LMCA is useful as an indicator of coronary atherosclerosis and may be a significant predictor of cardiovascular events, especially revascularization.

Prediction of left main coronary artery stenosis by exercise electrocardiography

The possibilities of predicting left main coronary artery stenosis (LMCAS) by the T wave pattern in exercise ECG were studied in a consecutive series of patients with stable angina pectoris and were compared to the predictive ability of ST criteria. After exclusion of patients with interfering diagnoses and digitalis treatment, 146 patients remained; 16 of them had LMCAS. Appearance or increase of a biphasic or negative T wave in leads V2-6 2 min after exercise detected 63% of the LMCAS, and the predictive value of a positive test was 36%. The sensitivity of the ST criteria was only 38% and the predictive value 26%. The observer concordance was 98% for the T wave and 84% for the ST criteria. These T wave criteria are at least as sensitive and predictive as the ST criteria and easier to apply.

Can left main or proximal left anterior descending coronary artery disease be assessed by non-invasive means?

One hundred consecutive patients with angina pectoris referred for coronary arteriography were studied prospectively for non-invasive assessment of left main (LMCA) or proximal left anterior descending coronary artery (proximal LAD) disease. Evaluation of echocardiographic interventricular septal motion, history and exercise test response could not identify the patients with these specific lesions. It is concluded that LMCA and proximal LAD disease still remain largely unpredictable by non-invasive means.

Prevalence of narrowing >or=50% of the left main coronary artery among 17,300 patients having coronary angiography

We sought to investigate the prevalence of left main coronary artery significant stenosis (LMSS) (>or=50% of the luminal diameter) in an angiographic series of patients, to describe the associated coronary stenoses, and to assess the influence of age and gender on these findings. The angiograms of 17,323 consecutive patients from January 1, 1984 to December 31, 2003 were retrospectively analyzed. LMSS was found in 823 patients (4.8%) and was more predominant in men (p <0.001). Men with LMSS (median age 63 years, interquartile range 57 to 69) were younger than the women (median age 67 years, interquartile range 61 to 72, p <0.001). Logistic regression analyses revealed male gender (odds ratio [OR] 1.79, 95% confidence interval [CI] 1.46 to 2.18, p <0.001) and age (OR 1.05, 95% CI 1.04 to 1.06, p <0.001) as independent predictors of LMSS. In the total series, luminal narrowing >or=50% in the right coronary artery, the left circumflex artery, the left anterior descending artery, the intermediate artery, first and second obtuse marginal branch, posterior descending artery, and posterolateral branch was significantly more frequent in association with LMSS. Approximately half of the patients with LMSS also had triple-vessel disease. Co-existent disease in 3 major vessels with minor branches was more evident in men (men/women OR 1.77, 95% CI 1.08 to 2.88, p = 0.02). In contrast, LMSS without lesions in any of the other coronary arteries was found in [corrected] 4.7% of patients with LMSS, and this was more frequent in women (men/women OR 0.31, 95% CI 0.15 to 0.61, p = 0.001). In conclusion, men presented more frequently with LMSS and at a younger age than women. Also, LMSS with co-existent triple-vessel disease was more common in men.

The Prognostic Importance of Nonsignificant Left Main Coronary Artery Disease in Patients Undergoing Percutaneous Coronary Intervention

OBJECTIVES

The purpose of this research was to study the association between nonsignificant (<50%) left main coronary artery disease (LMCAD) and short- and long-term survival in patients undergoing percutaneous coronary intervention (PCI).

BACKGROUND

The prognostic importance of nonsignificant LMCAD is unknown; however, the co-existence of nonsignificant LMCAD may influence revascularization decisions.

METHODS

We analyzed mortality and repeat catheterization rates of 11,855 patients in a prospective cardiac registry database who underwent single-vessel or multivessel PCI from January 1996 through December 2001. Of this cohort, 11.7% (n = 1,385) had nonsignificant (<50%) LMCAD. Outcomes were compared with those without LMCAD. A secondary analysis was performed on a larger cohort of 34,586 patients undergoing cardiac catheterization, irrespective of mode of revascularization therapy.

RESULTS

Patients with nonsignificant LMCAD had more co-morbidities, and a significantly higher crude mortality rate at 1 year compared with those without LMCAD (4.4% vs. 3.4%; p = 0.05). The 7-year crude mortality hazard ratio (HR) of PCI patients with <50% LMCAD versus those with no LMCAD was 1.18 (95% confidence interval [CI] 0.94 to 1.46). After risk adjustment for differences in baseline clinical profile, however, the HR decreased to 0.98 (95% CI 0.79 to 1.23). Repeat catheterization rates at 1 year did not differ between groups. The secondary analysis in all patients with nonsignificant LMCAD showed an adjusted HR of 1.03 (95% CI 0.94 to 1.14).

CONCLUSIONS

Patients undergoing single-vessel or multivessel PCI who have <50% LMCAD have a nonsignificantly increased 18% relative risk for mortality compared with those without detectable LMCAD that appears to be related to these patients' higher incidence of co-morbidities rather than the left main stenosis itself.

Atherosclerosis found on carotid ultrasonography is associated with atherosclerosis on coronary intravascular ultrasonography

OBJECTIVE

Little has been reported on the relationship between left main coronary artery atherosclerosis and carotid ultrasonographic results. We evaluated the association between carotid and coronary atherosclerosis assessed by coronary intravascular ultrasonography (IVUS) in 45 patients.

METHODS

We counted the number of plaques with intima-media thickness (IMT) greater than or equal to 1.1 mm and calculated a plaque score by summing all plaque thicknesses. With the use of IVUS, the percent plaque area was calculated at the proximal, middle, and distal sites of the left main coronary artery. The maximum percent plaque area and mean percent plaque area of the 3 sites were also calculated. Relationships among the degree of left main coronary artery atherosclerosis and carotid atherosclerosis and vascular risk factors were evaluated.

RESULTS

The mean percent plaque area and maximum percent plaque area were increased in men and in patients with hypertension compared with women and those without hypertension (P < .1). Both the average of the maximum common carotid IMT and plaque number were correlated with both the mean percent plaque area and maximum percent plaque area (P < .05). Men, the presence of hypertension, and the average of the maximum common carotid IMT were correlated with both the mean percent plaque area and maximum percent plaque area by multiple linear regression analysis (P < .05).

CONCLUSIONS

The average of the maximum common carotid IMT was significantly correlated with left main coronary artery atherosclerosis evaluated by IVUS.

Use of a simple clinical score to predict prognosis of patients with normal or mildly abnormal resting electrocardiographic findings undergoing evaluation for coronary artery disease

OBJECTIVE

To determine whether a simple clinical score, which was shown previously to predict the likelihood of severe coronary artery disease (CAD) in patients referred for coronary angiography, could predict prognosis in a separate cohort of patients with normal or mildly abnormal findings on their resting electrocardiogram (ECG) who were undergoing noninvasive evaluation for possible CAD.

PATIENTS AND METHODS

The study group included 2255 symptomatic patients with normal (n=1466) or mildly abnormal (nonspecific ST-T-wave abnormalities; n=789) findings on their resting ECG who were referred for exercise thallium testing between 1989 and 1991. Follow-up was 94% complete at a mean +/- SD duration of 6.9+/-1.5 years. The clinical score, which ranged from 0 (lowest risk) to 10 (highest risk), was calculated by awarding 1 point each for male sex, history of myocardial infarction, typical angina, diabetes mellitus, insulin use, and each decade of age older than 40 years.

RESULTS

In each ECG group, the clinical score was a significant predictor of cardiac death, nonfatal myocardial infarction, or late revascularization, considered individually or combined, unadjusted or with adjustment for age. Most patients had a score lower than 5; these patients had an excellent 5-year cardiac survival rate (99.7% for the normal ECG findings group and 98.8% for the ST-T-wave abnormalities group). The small subset of patients with a score higher than 5 had a much lower 5-year survival rate (923% for the 8% of patients with normal ECG findings and 86.6% for the 14% of patients with ST-T-wave abnormalities). For patients with a score of 5, the 5-year survival rate was 97.7% for the normal ECG findings group and 95.9% for the ST-T-wave abnormalities group.

CONCLUSION

In symptomatic patients with known or suspected CAD and normal or mildly abnormal resting ECG findings, this simple, easily computed clinical score is a useful and valid tool to help determine prognosis.

Left main coronary artery disease in adults younger than 50 years: a comparison with older patients

Left main coronary artery (LMCA) disease is a potentially lethal disease that can be effectively treated if it is recognized expeditiously. To determine whether clinical signs and symptoms vary with age, we examined data from 100 patients with angiographically significant LMCA disease (> or =50% stenosis). The majority of patients had myocardial infarction (32%) or Braunwald class I unstable angina (46%). There were no differences in initial symptoms, electrocardiographic findings (normal or only nonspecific changes in 52% of patients), or left ventricular function (normal or only mildly impaired in 76% of patients) between younger patients (< 50 yr; n = 29) and older patients (n = 71). Severe atherosclerosis was common in both groups. Risk factor profiles were different, however, in that diabetes mellitus (10% vs. 34%; P = 0.028) and hypertension (38% vs. 73%; P = 0.002) were less common and tobacco use was more common (79% vs. 39%; P <0.001) in younger patients. In summary, age influenced the risk factors associated with but not the clinical signs and symptoms of LMCAD.

Is left main coronary artery stenosis a risk factor for early mortality in coronary artery surgery?

It is accepted universally that the treatment of critical left main coronary artery (LMCA) stenosis is surgical revascularization. This study was designed to evaluate critical LMCA stenosis as a risk factor in coronary artery bypass surgery. We compared the surgical results of 760 patients with critical LMCA disease, including 58 cases who were operated under emergency conditions (LMCA-em) and 702 patients who were operated electively (LMCA-el), with randomly chosen 707 coronary bypass patients (CONT-el) without LMCA disease, but who had double- or triple-vessel disease. Another group of patients (n = 99) who were operated on under emergency conditions (CONT-em) but without LMCA disease were also compared with the corresponding groups. The mortality of LMCA-em group and CONT-em group was markedly higher from the other two groups. Univariate analysis revealed that female gender, older age, presence of diabetes mellitus, poor left ventricular function, and the presence of unstable angina were major risk factors for fatal outcome in LMCA-el and CONT-el groups. Age was also a risk factor in LMCA-em group, as well as unstable angina pectoris. The coexistence of critical right coronary artery disease did not affect the early outcome in both groups with LMCA lesions. In the multivariate analysis, critical LMCA disease was not a risk factor for mortality. Logistic regression analysis revealed diabetes [odds ratio (OR): 3.66], poor left ventricular function (higher left ventricle end-diastolic pressure, OR: 1.08), and emergent operations (OR: 5.09) were risk factors for early mortality. Patients with LMCA disease should have surgery promptly for favorable results, because emergency conditions have higher mortality rates.

Arterial patch angioplasty for reconstruction of proximal coronary artery stenosis

BACKGROUND

Ostium patch angioplasty and reconstruction with an onlay patch consisting of pericardium or the saphenous vein is an alternative surgical technique for patients with proximal coronary artery stenosis. Previously described surgical techniques comprise anterior or posterior approaches. In this article we report our experience of using a segment of the proximal right internal mammary artery as an onlay patch for surgical angioplasty.

METHODS

Between June 1997 and April 1999, 18 patients (9 men and 9 women) were subjected to surgical patch angioplasty of the left main coronary artery, 3 patients had an additional angioplasty performed on the proximal right coronary artery. The first 12 patients were operated with a posterior incision technique, and six subsequent patients by a new technique performed through an oblique incision into the left main stem after transsection of the ascending aorta.

RESULTS

All patients had an uneventful postoperative course, and were fully rehabilitated without clinical symptoms of ischemic heart disease at mean follow-up of 10 months (range 1-23 months). Postoperative catheterization after six days showed excellent results with a widely open and funnel-shaped neoostium.

CONCLUSIONS

The use of a proximal segment of the right internal mammary artery as an onlay patch for reconstructing proximal coronary artery lesions is safe with no complications. Although the posterior approach may be used to obtain excellent results, transsection of the ascending aorta gives an optimal visualization and mobilization of the left main coronary artery when performing surgical angioplasty.

One-year follow-up after intravascular ultrasound assessment of moderate left main coronary artery disease in patients with ambiguous angiograms

OBJECTIVES

The purpose of this study was to correlate angiographic and intravascular ultrasound (IVUS) findings in left main coronary artery (LMCA) disease and identify the predictors of coronary events at one year in patients with LMCA stenoses.

BACKGROUND

Significant (> or =50% diameter stenosis [DS]) LMCA disease has a poor long-term prognosis.

METHODS

One hundred twenty-two patients who underwent angiographic and IVUS assessment of the severity of LMCA disease and who did not have subsequent catheter or surgical intervention were followed for one year. Standard clinical, angiographic and IVUS parameters were collected.

RESULTS

The quantitative coronary angiography (QCA) reference diameter (3.91 +/- 0.76 mm, mean +/- 1 SD) correlated moderately with IVUS (4.25 +/- 0.78 mm, r = 0.492, p = 0.0001). The lesion site minimum lumen diameter (MLD) (2.26 +/- 0.82 mm) by QCA correlated less well with IVUS (2.8 +/- 0.82 mm, r = 0.364, p = 0.0005). The QCA DS measured 42 +/- 16%. During the follow-up period, 4 patients died, none had a myocardial infarction, 3 underwent catheter-based LMCA intervention and 11 underwent bypass surgery. Univariate predictors of events (p < 0.05) were diabetes, presence of another lesion whether treated with catheter-based intervention or untreated with DS > 50% and IVUS reference plaque burden and lesion lumen area, maximum lumen diameter, MLD, plaque area and area stenosis. Using logistic regression analysis diabetes mellitus, an untreated vessel (with a DS > 50%) and IVUS MLD were independent predictors of cardiac events.

CONCLUSIONS

In selected patients assessed by IVUS, moderate LMCA disease had a one-year event rate of only 14%. Intravascular ultrasound MLD was the most important quantitative predictor of cardiac events. For any given MLD, the event rate was exaggerated in the presence of diabetes or another untreated lesion (>50% DS).

Usefulness of three-dimensional transesophageal echocardiographic imaging for evaluating narrowing in the coronary arteries

Coronary artery (CA) imaging has relied on invasive techniques for diagnosing stenotic lesions. Two-dimensional techniques are limited in obtaining optimal longitudinal views of all segments of the CA because of their spatial orientations. Three-dimensional echocardiography (3DE) may produce any desired cross-sectional views and reconstruct 3-dimensional images from a volumetric data set. Its role in CA imaging has not been fully explored. The aim of this study was to evaluate the potential of 3DE in visualizing CAs and in assessing the severity of stenosis. We performed transesophageal 3DE in 46 patients. Images were collected sequentially with the transducer rotated through 180 degrees. From the 3DE data sets of all 46 patients, cross-sectional views and 3-dimensional images of CAs were reconstructed. For segment-by-segment comparison between CA angiography and 3DE in semiquantitative analysis of coronary stenosis, 5 segments were defined for the proximal CA tree in 20 patients who underwent both procedures. The left main, anterior descending, circumflex, and right CAs were visualized from 3DE in 100%, 100%, 98%, and 72%. The available lengths of these segments from 3DE were 12+/-4 mm (range 4 to 22), 15+/-6 mm (range 6 to 36), 30+/-12 mm (range 13 to 60), and 18+/-9 mm (range 6 to 36), respectively. Comparison between 3DE and CA angiography in semiquantitative estimation of CA stenosis resulted in complete agreement in 83% of the segments (kappa value = 0.7). The sensitivity and specificity of 3DE in detecting significant stenosis (> or =50%) were 84% and 97%. In conclusion, transesophageal 3DE allows imaging of the proximal CA, detection of stenotic lesions, and estimation of the severity of stenosis.

Impact of stents on clinical outcomes in percutaneous left main coronary artery revascularization

Despite effective treatment of left main coronary artery (LMCA) disease by coronary bypass, there is still need for treatment of the LMCA due to progression of disease or bypass graft failure. We compared the in-hospital and follow-up (1-year) outcomes of patients with LMCA stenosis treated with stents (n = 88), with a matched group of patients undergoing LMCA non-stent procedures (n = 36). Ninety-seven percent of patients in each group underwent previous coronary bypass. Procedural success (angiographic success without major in-hospital complications) tended to be higher in stent patients than in their non-stent counterparts (98% vs 92%, p = 0.12), and overall procedural complications were higher for the non-stent group (5.4% vs 0%, p = 0.03). The incidence of non-Q-wave myocardial infarction was higher in patients with the LMCA treated with stents than in non-stent patients (13% vs 2.7%, p = 0.09). There was no difference in death or Q-wave myocardial infarction between the 2 groups during follow-up. Overall target lesion revascularization at 1 year was 15% after LMCA stenting, and 18% in non-stent patients (p = 0.71). Also, any cardiac event-free survival (including death, Q-wave myocardial infarction, coronary bypass, or angioplasty) was similar for both groups (78% for stents vs 76% for non-stents, p = 0.85). We conclude that in patients undergoing LMCA interventions, stents reduce major hospital complications, but may not significantly reduce repeat revascularization or major cardiac events at 1 year compared with non-stent LMCA procedures.

Variations of remodeling in response to left main atherosclerosis assessed with intravascular ultrasound in vivo

Histopathologic studies have demonstrated that vessels enlarge to compensate for an increase in plaque burden; this has been confirmed in vivo using intravascular ultrasound (IVUS). The initial studies suggested a biphasic course of lesion formation with (1) preservation of lumen dimensions up to a plaque burden of approximately 40%, and (2) luminal narrowing as plaque burden further increases. In this study, we used IVUS and angiography to assess the extent of left main (LM) atherosclerosis in 107 patients undergoing catheter-based procedures of the left anterior descending or left circumflex coronary arteries. Using IVUS, atherosclerotic plaques were found in all LM arteries, but only 26 (24%) had varying degrees of luminal narrowing on the angiogram. Nevertheless, there was an inverse relation (r = -0.62, p <0.0001) between the minimal lumen area and the plaque burden (i.e., plaque + media divided by total vessel area) that was not restricted to plaque burden values >40% (or >30%), but persisted at plaque burden values of 20% to 40%. In addition, LM arteries with a plaque burden <40% had a similar total vessel area as did LM arteries with a plaque burden > or =40% (22.9 +/- 6.1 vs 21.8 +/- 4.8 mm2, p = 0.30). These data suggest that lumen dimensions may not be preserved even if plaque occupies no more than 20% to 40% of the total vessel area. Thus, there is more variation in remodeling response during earlier stages of plaque accumulation within the LM artery than is commonly suggested.

Comparison of surgical and medical group survival in patients with left main coronary artery disease. Long-term CASS experience

BACKGROUND

Observational and randomized studies designed to compare surgical and medical therapies in patients with left main coronary artery disease (LMCD) have shown that coronary artery bypass graft (CABG) surgery prolongs life in most patients with LMCD. The present report of 1484 patients with LMCD in the Coronary Artery Surgery Study (CASS) Registry extends the originally published 5-year surgical and medical group survival analysis to more than 16 years of follow-up and permits analysis of LMCD patient subgroups.

METHODS AND RESULTS

The CASS Registry contains 1484 patients with > or = 50% left main coronary artery stenosis initially treated with either surgical or nonsurgical therapy. The 15-year cumulative survival estimates were 37% for the 1153 patients in the surgical group compared with 27% for the 331 patients in the medical group. Median survival in the surgical group was 13.3 years (12.8 to 13.8 years, 95% confidence limits) compared with only 6.6 years (5.4 to 7.9 years) in the medical group (difference, 6.7 years; P < .0001). Median survival was also significantly longer in the surgical group stratified by age, sex, anginal class, left ventricular (LV) function, coronary anatomy, and the extent of LMCD. However, CABG surgery did not significantly prolong median survival in patient subgroups with (1) left main coronary stenosis of 50% to 59%; (2) normal LV systolic function; (3) normal or mildly abnormal LV systolic function and a right coronary artery stenosis > or = 70%; and (4) a nonstenotic (< or = 70%) right coronary artery. The 15-year cumulative survival for patients with normal LV systolic function in the surgical and medical groups was 42% and 51%, respectively. Median survival was 14.7 years in the surgical group and > 15 years in the medical group (P = NS). In patients with normal LV systolic function and a right coronary artery stenosis > or = 70%, the 15-year cumulative survival rates were also similar in the surgical and medical groups (40% and 48%, respectively). Median survival was 14.3 years in the surgical group and 14.2 years in the medical group (P = NS). The 15-year cumulative survival estimates for all subgroups were affected by convergence of the surgical and medical survival group curves owing to a disproportionate increase in the late surgical group mortality. Overall, 25% of patients in the medical group ultimately underwent CABG surgery. If all medical group patients had survived long enough, about 47% would be estimated to have had surgery by 15 years.

CONCLUSIONS

This report, which extends follow-up of more than 16 years in CASS Registry patients with LMCD, shows that CABG surgery prolongs life in most clinical and angiographic subgroups. However, median survival was not prolonged by CABG surgery in patients with normal LV systolic function, even if a significant right coronary artery stenosis (> or = 70%) also was present. These results extend our understanding of the natural history of LMCD and permit a more accurate estimate of long-term surgical and medical group survival.

Left main coronary artery disease: assessment, diagnosis, and therapy

This article reviews and updates the current literature concerning the assessment, diagnosis, and therapy of coronary disease involving the LMCA. Included is recent information regarding the natural history, congenital abnormalities, noninvasive diagnostic studies, and role of coronary bypass surgery and percutaneous coronary interventions in treating disease of the LMCA. At present, it remains that the LMCA is a difficult segment to assess angiographically. The use of noninvasive imaging does not specifically distinguish LMCA from other types of coronary disease. Coronary bypass surgery has a proven benefit in the treatment of disease of the LMCA. Currently, interventional procedures are limited by significant risks, and surgical treatment with coronary bypass surgery remains the therapy of choice.

Extent of atherosclerosis and remodeling of the left main coronary artery determined by intravascular ultrasound

This study used intravascular ultrasound (IU) to assess the incidence and extent of left main coronary artery (LMCA) disease and the effects of arterial remodeling. Sixty-nine patients undergoing cardiac catheterization were imaged with a 20 MHz rotational-tip IU device. Nine of the 69 studies (13%) could not be analyzed because of technical (n = 2) or anatomic (n = 7) reasons. Of the remaining 60 patients, 38 (63%) had at least 1 lesion in the left coronary artery perfusion territory by angiography; significant LMCA stenosis was present in 2 patients (3%). Intravascular ultrasonography demonstrated plaques in 27 of 60 LMCAs (45%), 6 of them in patients with normal angiograms. Twenty-four plaques (89%) were eccentric and calcium was present in 4 (15%). The mean minimal lumen diameter was 4.9 +/- 0.8 mm, the maximal lumen diameter was 5.6 +/- 0.8 mm, the planimetered lumen area was 22.6 +/- 6.0 mm2, the plaque area was 3.9 +/- 5.8 mm2, the vessel area was 26.5 +/- 5.9 mm2, and the area stenosis was 13 +/- 19%. In the 27 patients with plaque, plaque area was 8.7 +/- 5.7 mm2 and the area stenosis was 30 +/- 17%. The vessel area was significantly larger in diseased LMCAs (p < 0.001) and correlated with plaque area (r = 0.46). IU examination of the LMCA was feasible in 87% of patients and was more reliable for delineating plaques than angiography.

Use of sideholes for diagnostic coronary arteriography by Judkins technique in patients with ostial coronary stenosis

Patients with ostial left main coronary artery stenosis are at increased risk from diagnostic cardiac catheterization. In order to reduce this risk a modified Judkins coronary catheter with a sidehole 1.5-2 cm from the tip has been used in 6 patients in whom pressure damping was observed after initial use of a standard end-hole Judkins left coronary catheter. This eliminates damping and allows forceful hand injection with good proximal and distal vessel opacification. It also allows the acquisition of multiple views without the need for catheter removal after each injection, thereby reducing the risk involved in multiple cannulations of a vessel with a potentially unstable lesion at its origin. The technique has also been used for ostial lesions in a right coronary artery and a vein graft.

Exercise testing and left main coronary artery stenosis. Can patients with left main disease be identified?

Exercise testing is commonly used to evaluate patients with coronary artery disease who have serious anatomic characteristics. To study the characteristic exercise test variables in patients with left main coronary artery disease, the computerized data base of the Hungarian Institute of Cardiology Exercise Test Laboratory was used. Among 2,378 patients who had undergone a supine bicycle exercise test and who had abnormal coronary angiographic results, 65 patients with significant (greater than 50 percent diameter narrowing) stenosis of the left main coronary artery were found. The 65 patients were subgrouped according to their previous history and other vessel involvement. Nine patients had isolated left main coronary artery disease and no myocardial infarction (group 1); 28 patients had left main coronary artery stenosis and another diseased vessel but no prior myocardial infarction (MI) (group 2); and 28 patients had left main coronary artery disease, another diseased vessel, and a prior MI (group 3). For comparison, the 27 patients selected to be the control group (group C) had no history of MI but had significant stenosis of both the left anterior descending and the left circumflex arteries. Exercise time, calculated oxygen consumption, maximal work load, time to ST depression, prevalence of ST segment depression, and maximal ST depression were similar in the groups. Maximal heart rate and double product were higher in group 1, but we could find no single variable or group of variables characteristic of left main coronary artery disease.

Asymptomatic left main coronary artery disease in the Coronary Artery Surgery Study (CASS) registry

Left main coronary artery disease (i.e., greater than or equal to 50% stenosis) was found in 1,477 of 20,137 patients in the Coronary Artery Surgery Study (CAS) registry. Of these patients, 53 (3.6%) were asymptomatic. Asymptomatic and symptomatic patients were similar in regard to 1) severity of left main coronary artery stenosis (67% vs. 70%), 2) extent of proximal coronary artery disease (no differences in number of or severity of proximal stenoses), 3) left ventricular end-diastolic pressure (13 mm Hg vs. 14 mm Hg), 4) left ventricular wall motion score 9.1 vs. 8.7), and 5) number of coronary artery segments with greater than 70% stenosis (4.4 vs. 4.8). Among the asymptomatic patients, 47% received medical and 49% received surgical treatment. In the symptomatic group, 20% received medical and 78% received surgical therapy. The survival rate 5 years after surgery for treatment of left main coronary artery stenosis was 84% for the symptomatic patients and 88% for the asymptomatic patients (p = NS). Medical management of left main coronary artery disease produced a 5-year survival rate of 57% for asymptomatic patients and 58% for symptomatic patients. Within the asymptomatic subgroup, 88% of those surgically treated survived 5 years, whereas only 57% of those medically treated survived 5 years (p = 0.02). Thus, for CASS patients with left main coronary artery disease, the percentage of those that were asymptomatic is low (3.6%); asymptomatic and symptomatic patients with left main coronary artery disease had no significant difference in severity of left main coronary artery stenosis, extent of overall coronary artery disease, or left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival after myocardial infarction caused by acute left main coronary artery occlusion: case report and review of the literature

We report a 44-year-old white male presenting with an acute anterior myocardial infarction. Cardiac catheterization at 2 weeks postinfarction revealed total occlusion of the left main coronary artery. There was a normal dominant right coronary artery supplying moderate collaterals to the left coronary system. The patient was managed with conservative therapy and was N.Y.H.A. functional class II on followup 2 years later. A review of the literature relative to myocardial infarction caused by acute left main coronary artery occlusion is presented, and unique features of these cases are described.

Prediction of "critical" coronary disease: are the "Consensus Conference" guidelines adequate?

Presenting features of 100 patients with significant left main coronary stenosis (LMCS) were reviewed. All presented with angina--on minimal exertion in 45, moderate exertion in 38, and severe exertion in 6--and 11 had unstable angina. Although the resting ECG was normal in 44, exercise testing was positive in 92% of patients tested. The authors conclude that symptoms and the resting ECG alone are unhelpful in predicting "critical" coronary disease. However, application of a management plan similar to that suggested by the Consensus Conference on coronary artery surgery would have selected the vast majority of such patients for 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.

Prospective evaluation of the left main coronary artery using digital two-dimensional echocardiography

Recent clinical studies emphasize the importance of identification of patients with left main coronary artery obstruction. Although two-dimensional echocardiography can detect left main coronary artery disease, the technique requires frame by frame analysis, as no single frame provides all the necessary information. To determine if newly available computer-based digital processing techniques could overcome some of these technical difficulties, 119 consecutive patients were prospectively evaluated with two-dimensional echocardiography before coronary angiography. A continuous loop recording of the left main coronary artery was recorded as it passed through the ultrasonic beam in the short-axis view. Starting at a point when the vessel was first visualized, the ensuing eight consecutive fields, each 17 ms apart, were captured in digital format, thus providing a series of parallel, sequential, longitudinal slices of the left main coronary artery as it traversed the imaging plane. This was successfully accomplished in 100 (84%) of the 119 consecutive patients. By angiography, 16 patients (16%) had greater than 50% narrowing of the left main coronary artery. Digital echocardiography correctly identified 15 of these 16 patients (94% sensitivity) and accurately localized the lesion in 12 (80%) of 15. Of 84 patients without significant left main coronary artery obstruction, digital echocardiography correctly identified 78 (93% specificity). It was concluded that computer-based digital processing techniques can be applied to two-dimensional echocardiography to allow reliable visualization of the left main coronary artery. The technique provides more information than a single still frame and allows accurate noninvasive detection and possible localization of left main coronary artery lesions.

Detecting and excluding significant left main coronary artery narrowing by echocardiography

Two-dimensional echocardiography (2-D echo) of the left main coronary artery (LMCA) was attempted in 50 patients undergoing arteriography to evaluate 2-D echo for recognition of significant stenosis of the LMCA. Although the echocardiographer was experienced and used rigorous technique, visualization of the LMCA adequate for making a judgment regarding lumen reduction was possible in only 37 patients (74%). Of the 10 studies with suspected positive findings for LMCA stenosis by 2-D echo, 4 yielded true-positive and 6 false-positive results. A study from 1 other patient with LMCA stenosis by angiography was erroneously interpreted as negative by 2-D echo. Analysis of arteriograms in the 6 patients with false positive 2-D echo readings failed to implicate significant proximal left anterior descending artery narrowing as the cause of the errors. Although 2-D echo was correct in indicating the presence or absence of LMCA stenosis in 30 of 37 patients, and the predictive value of a negative 2-D echo response was 96%, the noninvasive method appears to be inadequate as a screening test. Widespread use of the procedure is limited by the 26% failure rate for adequate studies in experienced hands, and the implications of the occasional false-negative finding. If LMCA stenosis is suspected by 2-D echo in a patient who needs arteriography, the special care given to this possibility by the arteriographer should not harm the patient.

Diffuse slow washout of myocardial thallium-201: a new scintigraphic indicator of extensive coronary artery disease

When coronary artery disease is extensive and of relatively uniform severity, regional myocardial hypoperfusion may be balanced during stress, precluding development of spatially relative perfusion defects. Assessment of the washout of thallium-201 from myocardial regions may provide diagnostic assistance in these cases because washout analysis is spatially nonrelative and hypoperfused myocardial regions manifest a slow thallium-201 washout rate. In 1,265 consecutive patients having quantitatively analyzed stress-redistribution scintigraphy, 46 had a diffuse slow washout pattern with no or a maximum of one regional perfusion defect. Thirty-two underwent clinically indicated coronary angiography, and 23 (72%) of these were found to have three vessel or left main disease. Of 30 similar patients without a diffuse slow washout pattern and with no or a maximum of one perfusion defect, only 5 (17%) had extensive coronary disease. An independent relation between diffuse slow washout and extensive coronary disease was demonstrated by a Mantel- Haentzel chi-square analysis of a wide variety of other indexes of extensive disease. A diffuse washout abnormality, even in the absence of other scintigraphic, clinical or electrocardiographic indicators, carries a high predictive value for three vessel or left main coronary artery disease. The predictive value is maintained when the exercise level achieved is submaximal. Although an infrequent occurrence (3.6% of tested patients), a diffuse slow washout pattern without other scintigraphic indications of extensive coronary disease should lead to further diagnostic testing.

Occluded left main stem coronary artery. Report of five patients and review of published reports

Five patients aged 24 to 62 years presenting with a long history of angina were found to have complete occlusion of the left main coronary artery. In one patient the right coronary artery was also completely blocked. All patients had a dominant right coronary artery which was significantly diseased in only one patient. Ventricular function was severely impaired in only one patient. These patients illustrate the importance of collateral information in this condition. Coronary bypass grafting was performed in three patients who are now symptomatic at follow-up between nine and 17 months.

Echocardiographic detection of left main coronary artery obstruction

Advances in two-dimensional echocardiography have improved the prospects of using this technique to detect left main coronary artery (LMCA) obstruction. Using an echocardiograph that had digital gray scale, a 3-MHz transducer and strobe freeze-frame capability and reviewing recordings on an off-line videotape-videodisc analyzer, we retrospectively examined the LMCA in 72 patients who underwent coronary cineangiography. Angiography showed 50% or greater LMCA obstruction in seven patients. All seven had high-intensity echoes in the walls of the LMCA. The high-intensity echoes were irregularly located in the artery and partially occluded it. The LMCA could frequently be recorded proximal and distal to the obstruction. A blinded observer reviewed 28 randomly selected patients from this group and correctly identified the four patients with LMCA obstruction. There was one true and two questionable false-positive diagnoses. In a prospective study of 31 patients, two independent observers correctly identified the three patients with LMCA obstruction. There were no false negatives, and one observer had one false positive. All of the false positives were in patients with proximal left anterior descending coronary artery obstructions. Echocardiography may be a practical means of identifying patients with the LMCA obstruction.

Mortality related to cardiac catheterization and angiography

During a 14-month period, 75 deaths occurring in relation to 53,581 cardiac catheterizations were consecutively and prospectively reported to the Registry Committee of the Society for Cardiac Angiography. Three of the patients died several days after their catheterization from an unrelated cause and are excluded from this analysis. There were 21 patients (group I) who arrived at the laboratory in extremis and whose deaths were expected irrespective of the catheterization. Most of these patients suffered from recent myocardial infarctions and cardiogenic shock, or had complex congenital malformations. In 35 patients (group II), a cardiovascular complication occurring during the catheterization resulted in death. In 16 patients (group III) catheterization seemed uneventful, but death occurred suddenly 10 min to 10 h after the procedure. Of these 16 patients, eight had left main coronary artery obstruction greater than or equal to 90%, five had three-vessel disease all with 90% obstructions, one had 2-vessel disease both with 90% obstructions, and who had critical aortic stenosis. The 51 unexpected deaths (groups II and III) were considered to be causally related to the procedure, a mortality rate of 0.10%. Subsets with an increased mortality rate (M), were patients with: a) left main disease greater than 50% (M = 0.94%); b) ejection fraction less than 30% (M = 0.54%); c) NYHA class III or IV (m = 0.24%); d) age over 60 years (M = 0.23%); or e) three-vessel disease (M = 0.13%). In conclusion, catheterization related mortality occurs mostly in patients with far advanced cardiac disease. Nearly 1/3 of the unexpected deaths occurred suddenly after a seemingly uneventful procedure. Close monitoring after catheterization of patients with similar characteristics (left main disease greater than or equal to 90%, or three-vessel disease all greater than or equal to 90%) might disclose avenues for reducing mortality occurring after catheterization.

Effect of coronary bypass surgery on survival patterns in subsets of patients with left main coronary artery disease. Report of the Collaborative Study in Coronary Artery Surgery (CASS)

The 3 year cumulative survival rate of 1,492 patients with left main coronary artery disease (50 percent or greater stenosis of luminal diameter) enrolled in the Collaborative Study in Coronary Artery Surgery (CASS) was 91 percent for the surgical group and 69 percent for patients treated medically (p less than 0.0001). Mortality was significantly greater in patients with impaired left ventricular function. The difference between medical and surgical therapy was significant for patients who had normal, moderately abnormal and severely impaired left ventricular function and for patients with stenosis of the left main coronary artery of 50 to 59, 60 to 69, 70 to 79 and 80 percent or greater. Aortocoronary bypass surgery did not significantly improve survival in patient subgroups who had (1) a nonstenotic dominant right or balanced coronary circulation, (2) a stenotic dominant right coronary artery and normal left ventricular function, and (3) left main coronary stenosis of 50 to 59 percent and normal or mildly abnormal left ventricular function. The Cox proportional hazards model was used to select baseline variables that were independent predictors of long-time mortality. The model selected left ventricular score, age, congestive heart failure score, hypertension, percent left main coronary arterial stenosis and coronary arterial dominance as the baseline variables most predictive of long-term survival. A clinical and angiographic prognostic risk index developed from these six baseline variables showed significantly improved survival for the surgical cohort in each of four risk categories. In the best and worst risk category, the 3 year survival rate was 97 and 82 percent, respectively, for the surgical group and 85 and 34 percent, respectively, for the medical group (p less than or equal to 0.0002). The data from this observational study show that coronary bypass surgery prolongs life in most patients with left main coronary artery disease, particularly those who have severe narrowing of the left main coronary artery or impaired left ventricular function. The results permit a better understanding of the natural history of left main coronary artery disease and permit a more accurate estimate of long-term survival for individual patients through the use of a clinical-angiographic risk index.

Angiographic prevalence of high-risk coronary artery disease in patient subsets (CASS)

The prevalence of coronary artery stenoses greater than or equal to 70% or left main stenosis greater than or equal to 50% was evaluated in 20,391 patients who underwent angiography in the Coronary Artery Surgery Study from 1975-1979. After the patients with unstable angina or myocardial infarction were excluded, the disease prevalence in the 8157 patients with definite angina, probable angina, and nonspecific chest pain was 93%, 66% and 14% in men and 72%, 36% and 6% in women (p less than 0.001). The age and sex of the patients and character of chest pain were important determinants of disease prevalence and severity. Left main or three-vessel coronary disease occurred in more than 50% of middle-aged men and older women with definite angina and in more than 50% of men who had probable angina and were older than 60 years of age. In contrast, left main coronary disease occurred in less than 2% of 1282 men and less than 1% of 1397 women with nonspecific chest pain regardless of age. In this latter patient subset, less than 5% of men and less than 1% of women in each decade under 60 years had left main or three-vessel coronary artery disease. Thus, high-risk coronary disease is common in middle-aged patients with definite angina and older patients with probable angina, but is rare in patients with nonspecific chest pain. Indications and guidelines for diagnostic noninvasive tests and coronary angiography could be based on these results.

Accuracy of angiographic determination of left main coronary arterial narrowing. Angiographic--histologic correlative analysis in 28 patients

To evaluate the accuracy of coronary angiography in identifying severe narrowing of the left main coronary artery (LMCA), the degree of narrowing observed by angiography was compared to that observed at necropsy in 28 patients with symptomatic coronary heart disease in whom angiography had been performed within 40 days of death. The angiograms were evaluated independently by three experienced angiographers. In 20 of the 28 patients (71%), the degree of narrowing of the LMCA was either underestimated (13 patients) or overestimated (10 patients) by two or three of three angiographers; of 84 angiographic judgments made by the three angiographers in the 28 patients, 54 (64%) were underestimates (33 judgments, 39%) or overestimates (21 judgments, 25%) of the degree of LMCA narrowing. Of 12 LMCAs narrowed 76-100% in cross-sectional area at necropsy, six were underestimated at preoperative angiography by two or three of three angiographers; of 12 LMCAs narrowed 51-75% in cross-sectional area at necropsy, all 12 were either under- or overestimated angiographically by two or three of three angiographers; of four LMCAs narrowed 26-50% in cross-section at necropsy, two were overestimated by two of three angiographers. Thus, angiographic determination of degrees of narrowing of the LMCA during life is subject to considerable error. The angiographic errors appear to have resulted primarily from the presence of atherosclerotic plaque in the LMCA and an insufficient number of angiographic projections.

Risks of coronary arteriography and bypass surgery in patients with left main coronary artery stenosis

The risk of coronary arteriography is considerably increased in patients who have left main coronary artery stenosis (LMCAS). Among 1,060 patients undergoing coronary arteriography over a three-year period, 83 were found to have LMCAS and three of these patients died (3.6 percent) during or shortly after the arteriographic procedure. Bypass surgery, however, can now be carried out at a very low risk irrespective of the degree of coronary disease present--there was no hospital mortality in 74 patients with LMCAS undergoing bypass surgery at our institution during this period. In addition to careful attention to detail, techniques that can minimize the risk of both of these procedures in patients with LMCAS include invasive hemodynamic monitoring and various pharmacologic manipulations to prevent myocardial ischemia. In a small percentage of patients, rest angina may prove refractory to inhospital medical treatment, and intraaortic balloon pumping may be necessary to stabilize the conditions of these patients before proceeding with arteriography and myocardial revascularization.

Echocardiographic detection of coronary artery disease. Detection of effects of ischemia on regional myocardial wall motion and visualization of left main coronary artery disease

M mode and cross-sectional echocardiographic studies at rest have been used to detect regional left ventricular wall motion abnormalities as a sign of hemodynamically significant coronary artery disease. These techniques have proved to be fairly specific but not highly sensitive. Detection of new regional wall motion abnormalities with cross-sectional echocardiography during exercise appeared practical in 80 percent of patients in preliminary studies; the finding of such abnormalities is highly specific for the presence of coronary artery disease and, with this approach, the sensitivity of echocardiography is improved. Thus, patients with anatomically severe coronary artery disease on angiography may not manifest an echocardiographic abnormality in regional wall motion even during exercise. The direct noninvasive detection of the left main coronary artery in up to 90 percent of patients studied with cross-sectional echocardiography using the short axis or apical approach, or both, has been well defined. A high sensitivity and specificity of detecting anatomically severe left main coronary artery disease using the criteria of both luminal impingement and the presence of high intensity echoes have been confirmed. Further advances in imaging techniques may allow for better definition of the coronary arterial tree.

Operative risk factors in patients with left main coronary-artery disease

To identify the factors associated with operative mortality, we evaluated clinical, angiographic, and surgical variables in 1172 patients with left main coronary-artery stenoses of at least 50 per cent, who underwent coronary-bypass procedures in the Collaborative Study in Coronary Artery Surgery (CASS). The operative mortality was 4.2 per cent overall and was less than 3 per cent in seven of the 15 participating hospitals. Historical variables associated with an increase in operative mortality were age, female sex, and duration and severity of angina. Other variables associated most closely with poor survival were urgency of operation, left coronary-artery dominance, severity of left main coronary-artery stenosis, and impairment of left ventricular contraction. The results of this multicenter study show that aortocoronary bypass surgery in patients with left main coronary-artery disease can be performed with a low mortality and that patients at high risk can often be identified before surgery.

Surgery for left main coronary artery disease

The early and late results of the first 103 patients with left main coronary obstruction submitted to bypass grafting in South Australia are presented. A satisfactory hospital mortality of 2.9% and a surprisingly low late mortality of 2.9% (at an average follow-up time of 30 months), were obtained, and these figures, when taken in conjunction with a symptomatic relief rate of 83% at 24 months, have encouraged us to continue to recommend coronary artery grafting as the treatment of choice of left main stem disease.