Left Main Equivalent Disease Research Articles

Concomitant presence of subtypes of left coronary artery disease

Objective To study the risk profile associated with surgical revascularization for mixed left main and left main equivalent diseases. Methods and results Retrospective analysis of medical records of patients who underwent CABG from January 1997 and December 2002 were studied. 210 patients were included of which 30.5% (64) had left main, 49.5% (104) had left main equivalent and 20% (42) had mixed type of stenotic disease. The mixed type left coronary disease was associated with very high post-operative mortality. The factors associated with mortality were degree of left main artery stenosis, cardiopulmonary bypass pump time, no. of packed cell units transfused during surgery, post-operative low cardiac output, re-exploration of chest and no. of days spent as intubated. Low cardiac output, chest re-exploration and no. of days intubated were independently associated with mortality. Conclusions “Mixed left main and left main equivalent disease” makes a large proportion of left sided CAD. It is a unique subtype associated with very high risk, and it should be treated with extra caution. Characterization of its risk profile should be done with larger studies to improve the outcome.

Comparison of Surgical and Medical Group Survival in Patients With Left Main Equivalent Coronary Artery Disease

Combined severe proximal left anterior descending and proximal left circumflex coronary artery disease, or left main equivalent (LMEQ) disease, defines a prognostic high-risk angiographic subset of patients with chronic ischemic heart disease. While numerous observational and randomized clinical trials showed prolonged survival in surgically compared with medically treated patients with left main coronary artery disease, relatively few observational studies compared surgical and medical therapies in patients with LMEQ disease. The present report of 912 patients with LMEQ disease 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 LMEQ patient subgroups. The CASS Registry contains 912 patients with LMEQ disease, defined as combined stenoses of > or = 70% in the proximal left anterior descending coronary artery before the first septal perforator and proximal circumflex coronary artery before the first obtuse marginal branch, initially treated with either surgical or nonsurgical therapy. The 15-year cumulative survival estimates were 44% for the 630 patients in the surgical group and 31% for the 282 patients in the medical group. Median survival in the surgical group was 13.1 years (12.7 to 14.1 years, 95% confidence limits) compared with only 6.2 years (4.8 to 7.9 years) in the medical group (difference, 6.9 years; P < .0001). Median survival was also significantly longer in the surgical group stratified by age, sex, anginal class, left ventricular (LV) function, and coronary anatomy. However, coronary artery bypass graft (CABG) surgery did not significantly prolong median survival in patient subgroups with (1) normal LV systolic function, even if a significant right coronary artery stenosis (> or = 70%) also was present, and (2) mildly abnormal (LV score, 6 to 10) LV systolic function. The 15-year cumulative survival in patients with normal LV systolic function in the surgical and medical groups was 63% and 54%, respectively. Median survival was > 15 years in both the surgical and medical groups (P = NS). In patients with normal LV systolic function and right coronary artery stenosis > or = 70%, the 15-year cumulative survival was also similar in the surgical and medical groups (63% and 53%, respectively). Median survival was > 15 years in both the surgical and medical groups (P = NS). The 15-year cumulative survival estimates in all subgroups were affected by convergence of the surgical and medical group survival curves caused by a disproportionate increase in late surgical group mortality. Overall, 26% of patients in the medical group ultimately underwent CABG surgery. If all medical group patients had survived long enough, about 65% would be estimated to have had surgery by 15 years. When the CASS Registry patients with LMEQ disease who participated in the randomized trial or who were randomizable were analyzed, CABG surgery did not prolong the 15-year cumulative survival estimates compared with nonsurgical therapy for randomized (71% versus 67%, respectively) and for randomizable patients (62% versus 92%, respectively) with an LV ejection fraction > or = 50%. This report, which extends follow-up of more than 16 years in CASS Registry patients with LMEQ disease, 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 or in patients with an LV ejection fraction > or = 50% who participated in the CASS randomized trial or who were randomizable.

Long-term survival of medically treated patients in the Coronary Artery Surgery Study (CASS) Registry.

This study describes the impact of clinical, angiographic, and demographic characteristics on the long-term survival of Coronary Artery Surgery Study (CASS) patients while they were under medical treatment. Revascularization rates for the population are also provided. All CASS patients who had not received heart surgery before enrollment (23,467 patients) were included in this survival analysis while they were under medical treatment or surveillance. Follow-up time ranged from 0 to 17 years (median, 12 years). Long-term vital status is known for 95.8% of these patients. Log-rank tests, Kaplan-Meier survival curves, and Cox proportional-hazards regression are used to describe and assess the impact of patient characteristics on survival. Characteristics that had a significant impact on survival, in order of observed explanatory power, are age, number of diseased vessels, congestive heart failure score, smoking history, ejection fraction, sex, presence of left main coronary artery disease, presence of diabetes, left ventricular wall motion score, presence of other illnesses, history of myocardial infarction, and presence of left main equivalent disease. Overall, 12-year survival for patients with zero-, one-, two- and three-vessel disease is 88%, 74%, 59%, and 40%, respectively. Twelve-year survival for patients with at least one diseased vessel and ejection fractions in the ranges of 50% to 100%, 35% to 49%, and 0% to 34% is 73%, 54%, and 21%, respectively. High myocardial jeopardy, high anginal class, and two or three proximal diseased vessels characterize the profile of patients most likely to have received surgical treatment during follow-up. These results contribute to the understanding of the natural history of coronary artery disease and are also of historical interest. The poor survival of patients with three-vessel disease and low ejection fractions continues to emphasize the importance of considering revascularization for these patients.

Influence of right coronary artery stenosis on exercise test responses and survival in patients with left main or left main equivalent disease

Forty-two patients with angiographically documented left main coronary artery (LM) disease (luminal occlusion ≥50%) and 30 patients with left main equivalent (LMEQ) disease (≥70% luminal occlusion of both the proximal left anterior descending artery and proximal left circumflex artery) were studied to determine the role of right coronary artery (RCA) involvement on exercise test responses and survival. Significant (≥70%) RCA stenosis was present in 30 (72%) of the 42 LM patients and 16 (53%) of the 30 LMEQ patients. No significant differences were observed between LM and LMEQ patients in any clinical or exercise variables or survival. Thus both groups were combined for analysis of the influence of RCA involvement (i.e., LM/LMEQ with RCA versus LM/LMEQ without RCA disease). Greater ischemic responses were observed in the LM/LMEQ group with significant stenosis of the RCA. The presence of RCA stenosis was associated with significantly greater horizontal or downsloping ST-segment depression during exercise (2.4 ± 1.2 mm vs 1.3 ± 1.4 mm; p < 0.001), and prolonged recovery time until normalization of the ST segment (3.2 ± 1.4 min vs 2.0 ± 1.9 min; p < 0.01). The LM/LMEQ without RCA disease group behaved like the subgroup with two-vessel disease, and responses of the LM/LMEQ group with RCA disease were similar to the group with three-vessel disease. The annual survival in LM/LMEQ with RCA disease was worse than that in LM/LMEQ without RCA disease (average annual mortality rates = 7.5% vs 1.0%, respectively; p = 0.05). Infarct-free survival in LM/LMEQ with RCA disease was also lower than that in LM/LMEQ without RCA disease. Thus although patients with LM and LMEQ were similar in terms of survival and exercise responses, the presence of RCA stenosis was associated with significantly greater ST-segment depression, a prolonged recovery time until normalization of the ST segment, a fivefold increase in the death rate, and higher morbidity from myocardial infarction over a 5-year period of follow-up. Involvement of the RCA should be considered when making decisions concerning medical-surgical management of patients with severe coronary artery disease.

Predictors of disease severity and survival in patients with coronary artery disease.

The objective of this study was to determine whether coronary angiographic findings and survival could be predicted using standard clinical and exercise-test data. Five hundred and ninety-five men who had undergone both exercise treadmill testing and cardiac catheterization were followed for up to 5 years. Left main (LM) disease (> or = 50% stenosis) was present in 42 patients, whereas 30 patients had LM equivalent disease (> or = 70% stenosis of both the proximal left anterior descending and circumflex coronary artery disease (n = 152), one-vessel disease (n = 186), two-vessel disease (n = 118), three-vessel disease (n = 67), LM or LM equivalent disease without significant (> or = 70%) right coronary artery involvement (n = 26), and LM or LM equivalent disease with right coronary artery involvement (n = 46). ST-segment depression was more marked, whereas ejection fraction, maximal heart rate, maximal systolic blood pressure, and exercise capacity were lower in each group as disease severity worsened. Using Kaplan-Meier analysis, the subgroup with the poorest survival was found to be those with LM or LM equivalent disease with right coronary artery disease, and the next worse was the three-vessel disease group, in which survival was poorer than in all other subgroups (P < 0.01). Stepwise regression analysis revealed that the most powerful predictor for coronary artery disease severity was exercise-induced ST depression (P < 0.001), but it predicted survival poorly. History of congestive heart failure, low ejection fraction (50% or lower), and poor exercise capacity (5 metabolic equivalents or less) emerged as strong predictors of survival using stepwise Cox regression analysis (P < 0.001). Exercise-induced ST depression predicted the severity of angiographic disease but not survival, whereas the strongest predictors of survival were history of congestive heart failure, low ejection fraction, and poor exercise capacity.

Two- to eight-year survival rates in patients who refused coronary artery bypass grafting

One hundred and fifty patients with coronary artery disease (CAD) who refused bypass grafting were followed prospectively from 2 to 8 years. Mean age was 57 ± 8 (standard deviation) years. Ejection fraction averaged 70 ± 14%. Eight percent of patients had 1-vessel CAD and 92% had multiple-vessel CAD. Medical treatment included propranolol, nifedipine, isosorbide dinitrate, dipyridamole and aspirin. Annual mortality was 0% for 1- and 2-vessel CAD and 1.3% for left main equivalent disease, 3-vessel and left main CAD. Treatment significantly reduced the incidence of stable and unstable angina. Fifty-two patients (34%) had a second hemodynamic study 4.2 ± 1.3 years after initial evaluation. Stenosis progression or new significant obstructions (≥70%) In previously normal coronary arteries occurred in 61% of 123 arteries studied, whereas new occlusions were observed in 12% of the arteries. Nonfatal acute myocardial infarction incidence was 8%. No significant changes occurred in ejection fraction. In conclusion, proper medical treatment in selected patients with advanced CAD but preserved ventricular function is associated with good long-term survival and remission of symptoms, although progression of coronary atherosclerosis does occur in some patients.

Clinical features of left main equivalent coronary disease

The clinical presentation and hemodynamic, ventriculographic and coronary arterial findings of 70 patients with left main equivalent coronary artery disease (70 percent or greater reduction in luminal diameter of the left anterior descending and left circumflex vessels prior to any major branches) were compared with those of 75 patients with 60 percent or greater reduction in luminal diameter of the left main coronary artery. The group with left main equivalent disease did not differ significantly from the group with left main stenosis in any clinical descriptors including New York Heart Association functional class, age, sex distribution, type of presenting symptom or history of congestive heart failure or myocardial infarction. Similarly, the two groups did not differ in ejection fraction, cardiac index, left ventricular end-diastolic pressure, left ventricular end-diastolic volume index, extent of left ventricular contraction abnormality or prevalence of associated significant right coronary arterial obstruction. Of the 70 patients with left main equivalent disease, 31 were deemed to be in operable condition but did not undergo coronary bypass surgery for 1 or more months (mean 4.2 months, range 1 to 12). With the exception of four patients who underwent early operation because of unremitting symptoms, the groups undergoing early and delayed operation did not differ in symptomatic state. In the interim between cardiac catheterization and delayed operation, no patient died and one patient (3 percent) had an acute myocardial infarction. These low morbidity and mortality rates differ strikingly from those of patients with left main stenosis reported in the randomized Veterans Administration study, although the patients in the two studies manifested comparable severity of symptoms, extent of left ventricular contraction abnormality and associated right coronary disease. The results suggest that left main equivalent disease, as defined by obstruction of the left anterior descending and circumflex coronary arteries, does not carry the same short-term prognosis as left main coronary artery disease, but probably behaves more like ordinary two or, if the right coronary artery is also obstructed, three vessel coronary artery disease. In this sense, the term left main equivalent disease is a misnomer causing an unnecessary sense of urgency and alarm.

Surgical treatment of left main and left main equivalent coronary artery disease

There is a tendency to equate left main (LM) and left main equivalent (LME) coronary artery disease in terms of the surgical risk and benefit. Eighty-seven patients with LM disease were compared to 78 patients with LME disease as to operative mortality rate and long-term benefits. One hundred percent follow-up was obtained. Although the two groups were similar preoperatively with regard to age, sex, and ventricular function, the operative results in the two groups differed. There was a significantly higher operative mortality rate in the LM group of patients (12.6% versus 2.5%). However, the incidence of graft patency and relief of symptoms was lower in the LME group of patients. The late mortality rate was 4% in both groups. LME disease appears to represent a subgroup of patients with three-vessel disease and cannot be equated with LM disease.