Shahbudin H. Rahimtoola

Left main coronary artery disease: Risks of angiography, importance of coexisting disease of other coronary arteries and effects of revascularization

To elucidate the determinants of the poor prognosis of patients with left main coronary artery disease and to assess the efficacy of diagnostic and therapeutic interventions the angiographic features and clinical course of 58 patients with left main coronary artery disease studied between September 1967 and June 1974 were analyzed. Eighty-three coronary arteriograms were obtained in these 58 patients using the Judkins technique; there were no immediate complications although one patient died 3 days after study. Previously cited predictors of left main coronary artery, unstable or nonexertional angina and marked S-T segment depression with exercise were found in a minority of patients; thus, the presence of the disease could not reliably be predicted before arteriographic study. Coexisting disease was found in either two or three other coronary arteries in 46 of 58 patients; only 2 patients had isolated left main coronary artery disease. Because the criteria for operability have changed in recent years, current criteria without knowledge of the treatment actually given or its outcome. The condition of 10 of 58 patients was judged inoperable in retrospect because of severe coexisting distal coronary artery disease (8 patients) or ventricular dysfunction (2 patients). Of 19 patients whose condition was judged operable in retrospect but who were treated without surgery, 9 died, 8 within 18 months; 10 have survived 12 to 83 months. Another 27 patients with a condition judged operable in retrospect had received saphenous vein bypass grafts. In this group, there were four operative and three late deaths. The severity of angina decreased in survivors treated surgically but was unchanged in survivors treated without surgery. The improvement in survival rates of surgically treated patients was not statistically significant. The data indicate that coronary arteriography can be performed at low risk with the Judkins technique even though preangiographic prediction of left main coronary artery disease is unreliable. Coexisting disease in oter major coronary arteries is an important determinant of the poor prognosis of patients with left main coronary artery disease and precludes surgery in 13 percent. Isolated left main coronary artery disease is uncommon. Surgical therapy relieves symptoms more effectively than nonsurgical therapy.

Improvement in left ventricular wall motion following nitroglycerin.

Coronary artery disease patients frequently have left ventricular wall motion abnormalities. Though nitroglycerin is commonly used in ischemic heart disease, its effects on wall motion abnormalities is unknown. In this study we have evaluated the effects of nitroglycerin on wall motion abnormalities and on ejection fraction in 25 patients. Sixteen had coronary artery disease (>70% luminal narrowing). Six had no evidence of heart disease and three had congestive cardiomyopathies with normal coronary arteries. Left ventricular angiography was performed prior to and six minutes after administration of 0.4 mg of sublingual nitroglycerin. Twelve of the 16 coronary artery disease patients had wall motion abnormalities, and in seven of these, segmental wall motion improved after nitroglycerin. In five, wall motion did not change. The initial heart rate, left ventricular systolic and end-diastolic pressure, and left ventricular end-diastolic volumes were not different for those whose wall motion improved versus those whose did not. The increase in the former and fall in the latter three hemodynamic parameters were significant (P < 0.01) and similar for the two groups. In those whose wall motion abnormalities improved after nitroglycerin, ejection fraction (mean ± se) increased significantly (P < 0.05), from 0.47 ± 0.025 to 0.62 ± 0.046. In those without improvement, the ejection fraction went from 0.55 ± 0.056 to 0.58 ± 0.051 (NS). Three patients with congestive cardiomyopathy showed no improvement in ventricular wall motion or ejection fraction after nitroglycerin. Left ventricular wall motion abnormalities and ejection fraction improved in some coronary artery disease patients following nitroglycerin. The mechanism for this is unknown; however, ventriculography before and after nitroglycerin may be of potential usefulness for identifying areas of reversible wall motion abnormalities.

Coronary bypass for stable angina. A prospective randomized study

To evaluate the effects of coronary-artery bypass, 100 patients with stable, disabling angina were randomized to medical (49) or surgical (51) therapy. There was no statistical difference in major cardiac events after three years (death in five medical vs. four surgical, infarction in eight vs. 10, and unstable angina requiring operation or reoperation in eight vs. three cases). Surgical patients with three-vessel disease had fewer major events (P less than 0.05) than the comparable medical group and less unstable angina requiring operation (P less than 0.02). All unstable angina was less frequent in the surgical group (15 vs. six, P less than 0.01). Functional classification improved more in surgical patients at six months (P less than 0.01) and at late followup examination (P less than 0.05). After six months, surgical patients achieved significantly higher exercise work loads (P less than 0.01), exercise heart rates (P less than 0.05), maximum paced heart rates (P less than 0.01) and myocardial lactate extraction (P less than 0.01). On the basis of this interim report of a relatively small group of patients, we conclude that bypass results in greater functional improvement and less unstable angina than medical therapy. The likelihood of death and myocardial infarction is unchanged by operation.

Left Ventricular Wall Motion Assessed by Using Fixed External Reference Systems

Of two methods utilized to assess ventricular wall motion, one (method A) assumes the left ventricular wall moves symmetrically during contraction toward the approximate geometric center of the left ventricle. The other (method B) assumes the left ventricular wall moves symmetrically toward the base of the heart. Clearly, both methods cannot be correct in all patients. We are presenting a method (R) which utilizes two external markers and the diaphragm as an internal marker to evaluate left ventricular contraction pattern.Of 44 patients studied, the diaphragm moved in four and ventricular wall motion could not be assessed. Fifteen patients had valvular heart disease; six were normal. Findings in method R corresponded to those determined by method B in five of eight patients (63%) with left ventricular hypertrophy and by method A in eight of 13 patients (62%) without left ventricular hypertrophy. This difference was significant (P < 0.05). The remaining 19 patients had coronary artery disease; twelve of them had a previous myocardial infarction. In the latter, method R detected an area of asynergy (akinesis or dyskinesis) at ventriculography in ten of 12 patients (84%). The area of asynergy corresponded to the site of infarction determined by electrocardiogram in all patients. Methods A and B detected asynergy in only five of 12 patients (42%) and six of 12 patients (50%), respectively. Using two fixed external reference points and the diaphragm as an internal marker, a better evaluation of left ventricular wall motion can be obtained.

Effects of Ouabain on Coronary and Systemic Vascular Resistance And Myocardial Oxygen Consumption in Patients Without Heart Failure

The effect of digitalis glycosides on vascular resistance varies from one vascular bed to another and is also related to the hemodynamic state of the patient. To determine whether the rate of infusion is also a determinant of the vasoactive response the effect of various infusion rates of ouabain on the coronary and systemic beds was examined and the associated changes in myocardial oxygen consumption in patients without heart failure were quantitated. A 10 second and 2 minute infusion of ouabain (15 μg/kg body weight) produced 18.1 ± 5.6 percent and 7.5 ± 1.7 percent increases in mean arterial pressure and 23.7 ± 9.8 percent and 17.6 ± 7.5 percent increases in systemic vascular resistance, respectively (P <0.05 for each). A 15 minute infusion produced no statistically significant change in either variable. Coronary vascular resistance increased 13.4 ± 5.2 percent (P <0.05) after a 10 second infusion but did not change during or after a 15 minute infusion. The 10 second infusion was also associated with transient deterioration of myocardial lactate metabolism. Thirty minutes after ouabain administration mean arterial pressure had returned to control levels, but myocardial oxygen consumption remained increased by 12.5 ± 3.9 percent (P <0.025), indicating that ouabain produces a net increase in myocardial oxygen demand in patients without heart failure. Rapid intravenous administration of ouabain produces systemic and coronary arteriolar constriction that may lead to clinical deterioration. These effects can be avoided by slower delivery of the drug. Even in patients without heart failure, the increase in myocardial oxygen consumption with full digitalization is small.

The Prognosis of Patients with Coronary Artery Disease After Coronary Bypass Operations Time-Related Progress of 532 Patients with Disabling Angina Pectoris

The clinical progress of 532 patients who were treated for ischemic heart disease by coronary bypass grafting during a five-year period was studied. All patients had at least 50% luminal narrowing of one or more major coronary arteries determined by preoperative coronary arteriography and relatively stable and disabling (New York Heart Association Functional Class III and IV) angina pectoris. During the total observation period there were 35 deaths: 18 early and 17 late. The over-all 4-year survival rate by life-table methods was 89%, and it differed among patients with one-vessel involvement (96%), two-vessel involvement (89%), and three-vessel involvement (84%), but not significantly so. The patency rate of bypass grafts determined in 191 patients at a mean time of six months postoperatively was 76%. Functional class I and II status was 93% during the first year and was 75% during the fourth year after operation in observed survivors.

Spontaneous changes in left ventricular function between sequential studies

Abstract To evaluate day to day changes in left ventricular function, studies were performed in 17 patients in stable condition undergoing elective cardiac catheterizatlon and coronary arteriography on successive days. Seven patients had significant coronary artery disease, seven had significant valvular heart disease, two had both lesions, and one had no demonstrable heart disease. The group as a whole demonstrated no significant day to day changes in any measured parameter of left ventricular function …. The hematocrit decreased from 43.4 ± 4.3 to 41.5 ± 4.5 percent ( P The range of these day to day changes in the parameters of left ventricular function without therapeutic intervention must be considered when evaluating the effects of therapy. Since wall motion abnormalities were constant in site and showed little variation in extent, the effects of medical and surgical treatment on left ventricular asynergy can be assessed by sequential studies.

Late Results Following Emergency Saphenous Vein Bypass Grafting For Unstable Angina

Fifty-five consecutive patients with intermittent resting chest pain persisting more than 24 hours after hospitalization and accompanied by ECG changes representative of ischemia were operated urgently more than one year ago. Recent cases with shorter follow-up are excluded. Twenty-eight patients had single grafts, 23 had double grafts, three had triple grafts, and one a quadruple graft. There were three operative deaths (5%) and one sudden late death (2%). There were six early Mls and three late Mls. Follow-up ranges from 12 to 52 months (mean 24 months) with nine patients followed for four years. Actuarial analysis indicates a projected survival rate of 93% three years postoperative. Twenty-three survivors are Functional Class (FC) I, 19 are FC II, and eight are FC III. Functional class could not be determined in one survivor. Thirty patients had postoperative angiography one week to 32 months postop. 35/51 grafts were patent. Only three patients had no patent grafts. There were no significant differences between mean preoperative and postoperative left ventricular end-diastolic pressures (assessed in 20 patients) or ejection fractions (assessed in ten patients). The extremely low mortality early and late postop (7%), the low incidence of Ml (16%), and the excellent functional results after extended follow-up indicate that emergency saphenous vein bypass grafting is an effective therapy for unstable angina.

Frequency and significance of coronary arterial dominance in isolated aortic stenosis.

Myocardial infarction during aortic valve replacement has previously been reported to result from obstruction of a branch of the left main coronary artery by the perfusion cannula. Patients with a dominant left coronary arterial system may be at greater risk. To assess the frequency and significance of a dominant left coronary arterial system the coronary angiograms of 75 consecutive patients more than 34 years of age with isolated aortic stenosis were studied and compared with those of a control group of 150 patients. Among the patients with aortic stenosis, 19 (25 percent) had left dominance, 9 (12 percent) a balanced circulation and 47 (63 percent) a dominant right coronary arterial system. Among control patients, 14 (9 percent) had left dominance 18 (12 percent) a balanced system and 118 (79 percent) right dominance. The increased prevalence of left dominance in patients with aortic stenosis was significant (P less than 0.005). Among patients with aortic stenosis, the left main coronary artery was shorter (P less than 0.01) in those with left dominance (6.2 +/- 1.3 mm [mean +/- standard error]) than in those with right dominance (9.9 +/- 0.7). Sixty-nine patients with aortic stenosis underwent aortic valve replacement. Perioperative myocardial infarction occurred in 4 of 15 (26.7 percent) of those with left dominance and in 4 of 54 (7.4 percent) of those with right dominance or a balanced circulation (P less than 0.05). Perioperative myocardial infarction occurred in all three patients with left dominance and obstructive coronary artery disease. The increased prevalence of a dominant left coronary arterial system in aortic stenosis suggests that this may be part of a developmental complex. Patients with left dominance have a shorter left main coronary artery than patients with right dominance. They also have an increased risk of perioperative myocardial infarction if there is associated obstructive coronary artery disease. Preoperative information about the coronary arterial anatomy and extent of coronary artery disease may be helpful in planning the use of coronary perfusion and other myocardial preservation techniques during surgery in order to reduce the incidence of myocardial infarction.

Valve replacement—a perspective☆

Several potential hazards in the evaluation of patients with valve replacement are emphasized. A more uniform method of analysis of data is urgently needed. In the symptomatically disabled patient aortic and mitral valve replacement have improved both the quality of life and the length of life, provided that the disease is not far advanced. Anticoagulation with sodium warfarin is still needed in patients with prosthetic valves. Many important questions, including those related to ventricular function and choice of prosthetic devices, remain unanswered. The cost-benefit ratio and a weighting of various complications of valve replacement should be assessed. Many factors have to be taken into account before considering valve replacement early in the course of the patients disease.