Coronary arteriographic appearances in patients with left bundle-branch block

Multi-slice CT analysis of the length of left main coronary artery: its relation to sex, age, diameter and branching pattern of left main coronary artery, and coronary dominance

PURPOSE

The objective of this research was to analyze and correlate the length of the left main coronary artery (LMCA) with significant clinical parameters using multi-slice CT (MSCT).

MATERIALS AND METHODS

1500 patients (851 males and 649 females; mean age 57.38 ± 11.03 [SD]; age range: 5-85 years) who underwent MSCT scans from September 2020 to March 2022 were retrospectively included. The data were applied to generate three-dimensional (3D) simulations of a coronary tree using the syngo.via post-processing workstation. The reconstructed images were then interpreted, and the collected data were subjected to statistical analysis.

RESULTS

The results showed 1206 (80.4%) cases with medium LMCA, 133 (8.9%) with long LMCA, and 161 (10.7%) with short LMCA. The average diameter of LMCA at its midpoint was 4.69 ± 0.74 mm. The most frequent type of division of LMCA was bifurcation in 1076 (71.7%) cases; in 424 (28.3%) cases, the LMCA was divided into three or more branches. The dominance was right in 1339 (89.3%), left in 78 (5.2%), and co-dominant in 83 (5.5%) cases. There was a positive correlation between the length and branching patterns of LMCA, χ2 = 113.993, P = 0.000 (< 0.05). Other variables like age, sex, diameter of LMCA, and coronary dominance did not show any significant correlation.

CONCLUSION

This study has demonstrated a significant association between the length and the branching pattern of LMCA, which may be essential in diagnosing and treating coronary artery patients.

Prevalence and characterization of coronary artery disease in patients with symptomatic bradyarrhythmias requiring pacemaker implantation

Background

This study was conducted to assess the prevalence and characterization of CAD in high risk patients requiring pacemaker implantation for symptomatic bradyarrhythmias.

Methods

This study included 100 patients with symptomatic sinus node dysfunction or atrioventricular block, who were at high risk of CAD or had previously documented atherosclerotic vascular disease (ASCVD). Coronary angiography was performed before pacemaker implantation. CAD was defined as the presence of any degree of narrowing in at least one major coronary artery or its first order branch. Obstructive CAD was defined as ≥50% diameter stenosis. CAD was categorized as single vessel disease (SVD), double vessel disease (DVD), or triple vessel disease (TVD); and obstructive CAD in the arteries supplying the conduction system was sub-classified according to Mosseri's classification.

Results

Out of 100 patients (mean age 64.6 ± 10.7 years), 45 (45%) had CAD. 29% patients had obstructive CAD while 16% had non-obstructive CAD. 53.3% patients had SVD, 15.6% had DVD and 31.1% had TVD. Among patients with obstructive CAD; Type I, II, III and IV coronary anatomies were present in 6.9%, 34.5%, 10.3% and 48.3% patients respectively. Presence of CAD significantly correlated with dyslipidemia (p = 0.047), history of smoking (p = 0.025), and family history of CAD (p = 0.002).

Conclusion

Angiographic CAD is observed in a substantial proportion of patients with symptomatic bradyarrhythmias and risk factors for CAD. It could be argued that such patients should undergo a coronary work-up before pacemaker implantation. Treatment of concomitant CAD is likely to improve the long term prognosis of these patients.

Normal Proximal Coronary Artery Diameters in Adults from India as Assessed by Computed Tomography Angiography

INTRODUCTION

The normative data of coronary artery size among Indians are sparse. It is often essential to know the coronary dimensions especially during interventions such as stenting to choose the appropriate size of the stent and to decide the very need for stenting. In current practice it is the luminal angiography which is most widely employed to assess the coronary artery size. However, luminal angiography is not very accurate in estimating the epicardial coronary artery size as it does not take into account the mural thickness of the arterial wall. Hence it is prudent to assess coronary artery size by other methods such as Computed Tomography (CT) coronary angiography, quantitative coronary angiogram, Magnetic Resonanace (MR) angiogram, etc. In this study we chose computed tomography as it demonstrates mural thickness along with lumen of the vessels and hence measures the diameter more accurately.

AIM

To establish normative data for diameters of the proximal coronary artery segments during life by using MDCT in a cohort of individuals without any structural heart disease.

MATERIALS AND METHODS

Between October 2012 and April 2013, 168 consecutive patients who did not have any structural heart disease underwent CT coronary angiography for evaluation of Coronary Artery Disease (CAD) with atypical symptoms with low pretest probability. Patients who were found to have no coronary artery disease on CT-CAG were recruited in this study. The baseline clinical status and demographic data were obtained from the hospital records.

RESULTS

In our study we found that the mean indexed diameter to BSA among females for LMCA 2.32±0.12mm, LAD 1.95±0.15mm, LCX 1.73±0.20mm and RCA 1.84±0.22mm. For males the values were LMCA 2.33±0.13mm, LAD 1.94±0.16mm, LCX 1.74±0.21mm, and RCA 1.79±0.20mm. These values are comparable to other studies.

CONCLUSION

We attempted to establish normative data for normal proximal coronary artery dimensions among South Indian population. Coronary artery dimensions in Indians (in-dexed to BSA) for proximal major epicardial coronary arteries are similar to that reported in the West.

Coronary anatomy characteristics in patients with isolated right bundle branch block versus subjects with normal surface electrocardiogram

INTRODUCTION AND OBJECTIVE

Isolated right bundle branch block is a common finding in the general population. It may be associated with variations in detailed coronary anatomy characteristics. The aim of this study was to investigate the coronary anatomy in patients with isolated right bundle branch block and to compare that with normal individuals.

METHOD

In this case-control study we investigated the coronary anatomy by reviewing angiographic films in two groups of normal coronary artery patients: patients with right bundle branch block (RBBB) (n = 92) and those with normal electrocardiograms (n = 184).

RESULTS

There was no significant difference between the two groups in terms of diminutive left anterior descending artery, dominancy, number of obtuse marginal artery, diagonal, acute marginal artery, the position of the first septal versus diagonal branch, presence of ramus artery, and size of left main artery. The number of septal branches was higher in the case group (p-value <0.001). Origination of the atrioventricular node artery from the right circulatory system was more common in both groups but cases showed more tendency to follow this pattern (p-value = 0.021). The frequency of the normal conus branch was higher in the cases versus controls (p-value = 0.009).

CONCLUSIONS

Coronary anatomy characteristics are somewhat different in subjects with RBBB compared to normal individuals.

Incidence of cardiovascular disease in the dissecting room: A valuable teaching asset

The purpose of this study was to determine the incidence of cardiovascular pathology in 50 cadavers in the dissecting room of the Department of Anatomy at Guy's Campus, King's College, London, and to demonstrate the importance of dissection in teaching the anatomy of normal and pathological hearts. After external evaluation of each heart the four chambers were dissected and studied. The features noted included evidence of coronary atherosclerosis, myocardial infarction, variations in coronary artery anatomy, valvular disease, variations in left ventricular wall thickness and atrial dimensions, and atrial anomalies. All the hearts studied had at least one pathology. The majority had severe coronary atherosclerosis (44) and aortic valve pathology (23). A large number had left ventricular hypertrophy (13) and left atrial enlargement (9). A small number showed evidence of myocardial infarction (4). Anatomical anomalies were also found, and included persistent foramen ovale (1), three coronary arterial ostia (3), and anatomical variations of the orientation of the main stem of the left coronary artery (2). This study demonstrates that dissection is not only an excellent way of studying normal cardiac anatomy, but also a valuable method for introducing common cardiac pathologies to the medical student.

Main trunk of the left coronary artery: Anatomic study of the parameters of clinical interest

The objective of this study was to analyze in one single series all the characteristics of the main trunk of the left coronary artery (MT) that may be of use in the diagnosis and treatment of its pathologies. One-hundred human hearts from autopsies were used. The average age of the sample studied was 63.15 years +/- 18.76 (range = 17-94 years). The heart was removed after resection of the costosternum and placed in 10% formaldehyde. With gradual separation and retraction of the myocardial fasciculi the MT was exposed. The length of the MT, the luminal diameter of the MT at its midpoint, and the luminal diameter of the left coronary orifice were measured with a caliper. The angle of division between the anterior interventricular and circumflex branches was also measured, and the number of terminal branches originating from the MT was recorded. In four cases, there was no MT and the anterior interventricular and circumflex branches originated directly from the left aortic sinus. The average length of the MT was 10.8 +/- 5.52 mm (range = 2-23 mm); the average diameter at its midpoint was 4.86 +/- 0.80 mm; and there was no significant difference noted between the midpoint diameter of the MT and the diameter of the left coronary orifice. The most frequent type of division of the MT was bifurcation (62%); in 38% of cases the MT divided into three or more branches. An average value of 86.7 +/- 28.8 degrees was obtained for the angle of division of the terminal branches of the MT (range = 40-165 degrees ). There was a positive correlation between the length of the MT and the angle of division of its terminal branches, with the longest MTs having the largest angle of division.

Prognostic value of pharmacologic stress echocardiography in patients with left bundle branch block

PURPOSE

Although coronary artery disease is a frequent cause of left bundle branch block, the prognostic value of myocardial ischemia in patients with this conduction abnormality has not been defined. We investigated the value of pharmacologic stress echocardiography in risk stratification of patients with left bundle branch block.

PATIENTS AND METHODS

Three hundred eighty-seven patients [230 men and 157 women, mean (+/- SD) age, 64 +/- 9 years] with complete left bundle branch block on the resting electrocardiogram underwent dobutamine (n = 217) or dipyridamole (n = 170) stress echocardiography to evaluate suspected or known coronary artery disease. A summary wall motion score (on a one to four scale) was calculated. The primary end points were cardiac death and nonfatal myocardial infarction.

RESULTS

A positive echocardiographic result (evidence of ischemia) was detected in 109 (28%) patients. During a mean follow-up of 29 +/- 26 months, there were 21 cardiac deaths and 20 myocardial infarctions, 63 patients underwent coronary revascularization, and 1 patient received a heart transplant. In a multivariate analysis, four clinical and echocardiographic variables were associated with increased risk of cardiac death: resting wall motion score index [hazard ratio (HR) = 7.5 per unit; 95% confidence interval (CI), 2.8 to 20; P = 0.001], previous myocardial infarction (HR = 2.9; 95% CI, 1.1 to 7.3; P = 0.02), diabetes (HR = 2.7; 95% CI, 1.1 to 6.6; P = 0.03), and the change in wall motion score index from rest to peak stress (HR = 3.0 per unit; 95% CI, 1.0 to 8.6; P = 0.04). The 5-year survival was 77% in the ischemic group and 92% in the nonischemic group (P = 0.02). Four variables were associated with increased risk of cardiac death or infarction: previous myocardial infarction (HR = 3.4; 95% CI, 1.7 to 6.8; P = 0.0005), diabetes (HR = 2.4; 95% CI, 1.2 to 4.6; P = 0.01), resting wall motion score index (HR = 2.2 per unit; 95% CI, 1.1 to 4.1; P = 0.02), and positive echocardiographic result (HR = 2.2; 95% CI, 1.1 to 4.5; P = 0.03). The 5-year infarction-free survival was 60% in the ischemic group and 87% in the nonischemic group (P < 0.0001). Stress echocardiography significantly improved risk stratification in patients without previous myocardial infarction (P = 0.0001), but not in those with previous myocardial infarction (P = 0.08). In particular, it provided additional value over clinical and resting echocardiographic findings in predicting cardiac events among patients without previous infarction.

CONCLUSIONS

Myocardial ischemia during pharmacologic stress echocardiography is a strong prognostic predictor in patients with left bundle branch block, particularly in those without previous myocardial infarction.

Diagnosis of coronary artery disease with Tl-201 SPECT in patients with left bundle branch block: importance of alternative interpretation approaches for left anterior descending coronary lesions

Left bundle branch block (LBBB) is a strong predictor of mortality in the presence of coronary artery disease (CAD). Noninvasive evaluation of CAD in these patients has some difficulties. Exercise-induced electrocardiographic ST segment changes are nondiagnostic, and several scintigraphic studies have reported false-positive anteroseptal and septal perfusion defects up to 80%. The authors aimed to assess the diagnostic accuracy of thallium-201 (Tl-201) exercise myocardial single photon emission computerized tomography (SPECT) in comparison with coronary angiography (CAG) for detection of CAD in patients with LBBB. Seventy-seven consecutive patients suffering from chest pain with complete and permanent LBBB were included in the study. All patients (40 women, 37 men, mean age = 54 +/- 7 years) were studied with Tl-201 exercise SPECT and coronary angiography. Tl-201 exercise SPECT for diagnosis of left anterior descending (LAD) artery lesions was interpreted by using three different approaches: method A (conventional approach), method B (involvement of anterior and septal wall regardless of apical wall), and method C (apical approach: involvement of anterior septal and apical wall). Methods A and B gave a sensitivity of 100% each but a specificity of 47% and 56%, respectively. Although method C gave a higher value of specificity than that of methods A and B (98% vs 47% and 56%, respectively p < 0.05), the sensitivity of method C significantly decreased in respect to methods A and B (33% vs 100% p < 0.01). Isolated septal defects were evaluated separately. Isolated septal defects on exercise Tl-201 SPECT were detected in 11 patients, and none of them had CAD according to CAG results. Isolated septal wall involvement had a sensitivity of 0% and a specificity of 74%. The sensitivity and specificity of Tl-201 SPECT for diagnosis of CAD in the right coronary and left circumflex artery territories were 91% and 89%, respectively. In conclusion, the apical approach increased the specificity and decreased the sensitivity of the test. Isolated septal defects seem to have no value for diagnosis of CAD in patients with left bundle branch block.

Are Asian coronary arteries smaller than Caucasian? A study on angiographic coronary artery size estimation during life

Asian immigrants to the UK have a higher mortality from coronary artery disease (CAD) than native Caucasians. There is a clinical impression that Asians have smaller coronary arteries than Caucasians. In the present study, consecutive series of 72 male Caucasian and 70 male Asian patients undergoing diagnostic coronary angiography were recruited. Measurements of proximal disease-free segments of the three major coronary arteries were made using the catheter tip as the calibrating object. Electronic callipers were used for all measurements. Total coronary artery diameter was derived by adding the diameters of right, left anterior descending and circumflex arteries. Asians had significantly smaller total vessel diameter compared to Caucasians. They also had smaller body surface areas. This observation has important therapeutic implications regarding coronary intervention in this ethnic group already suffering excess mortality from CAD.

Diagnostic accuracy of exercise thallium-201 single-photon emission computed tomography in patients with left bundle branch block

Recent reports have proposed that abnormal apical or anterior wall perfusion with exercise thallium-201 imaging may increase diagnostic accuracy for disease of the left anterior descending artery in patients with left bundle branch block (LBBB). To evaluate these suggestions, 83 patients with LBBB who underwent thallium-201 single-photon emission computed tomography and coronary angiography within an interval of 3 months were retrospectively reviewed. There were 59 men and 24 women aged 33 to 84 years (mean 65). Myocardial perfusion to the apex, anterior wall and anterior septum were scored qualitatively by consensus of 2 experienced observers and by quantitative analysis in comparison with a normal data base. The sensitivity, specificity and accuracy of perfusion defects in these segments were then expressed according to angiographic findings. Significant stenosis of vessels within the left anterior descending artery territory was present in 38 patients. By receiver-operator characteristic analysis, a fixed or reversible defect within the apex by the qualitative method was the best criterion for coronary artery disease. However, although highly sensitive (79 and 85% by the qualitative and quantitative methods, respectively), an apical defect was neither specific (38 and 16%, respectively), nor accurate (57 and 46%, respectively). Perfusion abnormalities in the anterior wall and septum were also of limited diagnostic accuracy. Thus, modified interpretative criteria in patients with LBBB are not clinically useful in the assessment of left anterior descending artery disease.

The effect of baseline electrocardiographic abnormalities on the diagnostic accuracy of exercise-induced ST segment changes

Although exercise-induced ST segment depression is thought to be unreliable marker of myocardial ischemia in the presence of resting electrocardiographic changes, this conclusion is based on limited and disparate data from studies often lacking acceptable measures of ischemia. To determine the diagnostic accuracy of the ST segment response in a blinded prospective protocol, we compared ST deviation to thallium201 SPECT scintigraphy in 95 patients during exercise. Diagnostic accuracy was poor in the 95 patients with resting abnormalities: left bundle branch block (LBBB) = 70%, complete right bundle branch block (cRBBB) = 75%, incomplete right bundle branch block (incRBBB) = 79%, intraventricular conduction delay (IVCD) = 44%, left ventricular hypertrophy (LVH) = 59%, digitalis = 53%, compared with a diagnostic accuracy of 90% in 29 patients without resting changes. There were 20 false negative and 17 false positive ST segment responses. The extent and direction of resting ST deviation varied substantially and had no influence on diagnostic accuracy. The extent of change in ST deviation with exercise required for a positive response did not alter diagnostic accuracy: -1.0 mm = 61%, -1.5 mm = 63%, and -2.0 = 61%. While the location of regional ischemia did not influence the accuracy of ST segment analysis, a QRS duration less than 120 msec did improve diagnostic accuracy. Our data confirm that ST segment analysis with exercise testing is not reliable in patients with resting electrocardiographic abnormalities and demonstrates that accuracy is not improved by adjusting for either resting or exercise-induced ST segment changes or for location of the ischemic region.

Left bundle branch block: a predictor of poor left ventricular function in coronary artery disease

Clinical, coronary arteriographic, and hemodynamic studies were performed in 55 patients with left bundle branch block (LBBB) and coronary artery disease and were compared with 110 patients consecutively matched for age and sex with ischemic heart disease but without LBBB. No significant differences were found in duration of symptoms or frequency of prior myocardial infarction, hypertension, or diabetes mellitus; however, the LBBB patients had a significantly (p less than 0.001) higher frequency of congestive heart failure (38.2% vs 11.8%) and cardiomegaly (63.6% vs 25.5%). An evaluation of severity of the coronary disease on the basis of subtotal vs total obstructive lesions, number of vessels involved, total coronary score, and individual coronary arteries involved revealed no significant differences between the groups. The LBBB patients had significantly (p less than 0.001) greater impairment of left ventricular function as reflected by the end-diastolic volume (107 +/- 43 vs 79 +/- 30 ml/m2), ejection fraction (0.35 +/- 0.19 vs 0.59 +/- 0.18), and frequency of an abnormal contractile pattern (91% vs 61%). Evaluating the LBBB patients on the basis of the QRS width and axis revealed no significant intragroup differences in clinical profile, severity of coronary disease, or left ventricular dysfunction. A prolonged PR interval (greater than or equal to 0.20 second) was associated with more severe coronary artery disease and an enlarged heart. This study indicates that coronary artery disease associated with LBBB identifies patients with severe left ventricular dysfunction.

Coronary angiographic assessment of left posterior hemiblock

The ECGs of 1,095 patients with coronary angiographic evidence of significant coronary artery disease (greater than or equal to 50% obstructive lesion in at least one major coronary artery) were reviewed. Five patients had left posterior hemiblock (LPHB), an incidence of 0.5%. Three of five patients also had a right bundle branch block (RBBB). Of the five patients with LPHB, all had significant right coronary artery (RCA) disease (four complete occlusions, one 90% obstructive lesion). All five patients having LPHB also had evidence of critical disease (greater than or equal to 75% obstruction) of at least one of the major branches of the left coronary artery; four of the five had complete occlusion of the left anterior descending coronary artery (LAD). The left circumflex coronary artery (CFx) was critically diseased in three patients. The ECGs of four patients showed evidence of only one myocardial infarction while one patient had evidence of an anterior and an inferior infarction. It is concluded that the presence of LPHB in patients with coronary artery disease is an ominous electrocardiographic finding, and is associated with extensive coronary artery disease.

The pathologic correlates of the electrocardiogram: complete left bundle branch block

To assess whether gross pathologic differences exist between hearts with left bundle branch block (LBBB) and left-axis deviation (LAXD) and those with LBBB and a normal frontal plane axis, we examined 70 hearts with LBBB in a series of 1410 sequential dissections (5%). Thirty-two hearts had LAXD and 34 had normal axes on the correlative ECG. Left ventricular enlargement occurred frequently (93%). No significant differences were found in age distribution, left ventricular weight, coronary anatomy or infarct location. Quantitative analysis revealed larger inferoposterolateral and apical infarcts in hearts with LBBB and LAXD (p less than 0.01). The accuracy of various electrocardiographic signs of left ventricular enlargement and myocardial infarction in the presence of LBBB was assessed. Voltage criteria and QRS duration poorly define anatomic chamber enlargement. Anterior infarction is suggested by a q or pathological Q wave in lead I, a q wave in leads I, V5 and V6, or notched S waves in V3 or V4. Pathologic q waves or ST shifts in the inferior leads have high diagnostic specificity but low sensitivity for inferior infarction.

Accelerated atherosclerosis in subjects with some minor deviations from the common type of distribution of human coronary arteries

Gross dissection of the coronary arteries of 566 subjects aged 0--45 years from an unselected population sample of Bucharest revealed the presence of a similar anatomical branching pattern in 58% of cases. Starting from this common type of distribution of coronary arteries, some minor deviations were detected coexisting with a thicker intima, a more rapid onset and evolution of atherosclerotic plaques, and a more important degree of luminal obstruction. Among the 15 minor deviations described in this paper, 3 were constantly associated, 9 only occasionally associated and 3 not associated with an accelerated atherosclerosis. The most important of these atherogenic deviations was present in 29% of cases or in 1 out of every 3 or 4 subjects. In essence, these deviations consisted of an excessive increase in external diameter and length of the left coronary arterial system, coexisting with an underdeveloped right coronary arterial system, or vice versa. The atherogenic deviations from the common type of distribution of the coronary arteries seemed to represent an important genetically transmitted risk factor for coronary heart disease.

Clinical and pathologic features of obstructive disease in the predominant right and left coronary circulations in man

The clinical features and the location and severity of obstructive coronary artery disease are contrasted in 98 patients with predominant left and 99 patients with predominant right coronary circulations. A significantly higher incidence of ventricular conduction disturbances and a greater incidence and severity of obstructive coronary artery disease (greater than or equal to 70% cross-sectional narrowing in the proximal left anterior descending, circumflex and right coronary arteries and their major branches) distinguish the predominant left from the predominant right coronary circulation. The results suggest an anatomically disadvantaged status for the predominant left compared with the predominant right coronary circulations with respect to ventricular conduction disturbances and to coronary atherogenesis in man.

Ability of the R-wave change during stress testing to accurately detect coronary disease in the presence of left bundle branch block at rest

The treadmill stress test and antiographic records of 18 patients with left bundle block on resting ECG were reviewed retrospectively. Thirteen of the patients had significant coronary artery disease defined as greater than or equal to 70% cross-sectional narrowing of one or more vessels, while 5 patients were hemodynamically and angiographically normal. The R-wave and ST-segment response to exercise were determined in each case and compared. A positive R-wave response was an exercise-induced increase or no change in amplitude over the baseline level, while a positive ST-segment response was greater than or equal to 2 mm of excerise-induced depression over the baseline level. The sensitivity for the R-wave response was 69% (9 of 13), the specificity was 100% (5 of 5), and the predictive value was 100% (9 of 9). For ST depression these values were 46% (6 of 13), 40% (2 of 5)8 and 67% (6 of 9). Although the number of patients in this study is small--a reflection of the fact that ST depression in the presence of left bundle branch block with exercise is associated with many false positive responses and hence less referral for stress testing--it appears that the R-wave response to exercise in the presence of left bundle branch block can accurately detect coronary artery disease.

Analysis of exercise-induced R wave amplitude changes in detection of coronary artery disease in asymptomatic men with left bundle branch block

The exercise electrocardiograms of 44 asymptomatic men with acquired left bundle branch block were analyzed for changes in R wave amplitude. Results were correlated with findings on selective coronary angiography. There were two subgroups: 7 men with significant angiographic coronary artery disease (Group I) and 37 with normal coronary angiograms (Group II). Exercise induced an increase in R wave amplitude in all seven men with coronary artery disease but in only 10 of the 37 men without significant coronary artery disease. This criterion thus had a sensitivity of 100 percent but a poor specificity of 73 percent, a predictive value of 41 percent and an accuracy rate of 77 percent for the diagnosis of coronary artery disease. The greater the increase in R wave amplitude the greater was the likelihood of some degree of left ventricular dysfunction as measured by wall motion abnormalities and elevated left ventricular end-diastolic pressure. The increase in R wave amplitude with exercise appears to be a sensitive test in identifying coronary artery disease in asymptomatic men with acquired left bundle branch block.

Is the treadmill exercise test useful for evaluating coronary artery disease in patients with complete left bundle branch block?

To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary angiographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.

Left coronary artery anatomy in patients with bicuspid aortic valves

The anatomy of the proximal left coronary artery in 33 adult patients with bicuspid aortic valves was compared with that in 33 adult patients with aortic valve disease of other aetiologies and with that in 50 adult control patients with no valve or congenital heart disease. Patients with bicuspid aortic valves had a higher incidence of immediate bifurcation of the left main coronary artery, of left main coronary length less than 10 mm, and of left coronary artery dominance. The mean length of the left main coronary artery was significantly less in the patients with bicuspid aortic valves. These variations from the usual coronary artery anatomy may be part of the developmental abnormalities responsible for bicuspid aortic valves, and require evaluation and consideration when considering angiography and valve replacement in patients with aortic stenosis.

Electrocardiographic criteria of left ventricular hypertrophy in left bundle-branch block

In order to determine whether the electrocardiographic criteria of left ventricular hypertrophy apply in the presence of left bundle-branch block we studied 79 cases of intermittent left bundle-branch block and compared the QRS voltage and axis before and after its onset. Cases of incomplete left bundle-branch block were excluded. There was a statistically significant correlation between pre- and post-left bundle-branch block values of R or S wave voltage in leads I, V1, V2, V5, and V6, the Sokolow index (R V5 or V6 + S V1), and the QRS axis. There was a statistically significant reduction in R wave voltage in leads I, V5, and V6, an increase in S wave voltage in V1 and V2, and leftward shift of QRS axis, but the Sokolow index remained unchanged, after the onset of left bundle-branch block. The Sokolow criteria for left ventricular hypertrophy apply satisfactorily even in the presence of left bundle-branch block, though specificity is low, but QRS axis is unhelpful.

The length of the left main coronary artery: pathological features

The mean length of the LCA found by pathological (or angiographic) methods is fairly constant. This exclusively anatomical study shows no significant relationship between the length of the LCA and stenotic atherosclerosis in the LCA or the heart weight or a dominant left circumflex coronary artery or a complete His left bundle-branch block.

The electrocardiographic response to maximal treadmill exercise of asymptomatic men with left bundle branch block

This study presents the results of maximal treadmill testing and coronary angiography in 31 asymptomatic USAF aircrewmen with acquired left bundle branch block. There were two subgroups: 26 men with normal coronary angiography and five men with significant angiographic coronary angiography and five men with significant angiographic coronary artery disease. The mean amount of maximal ST-segment depression induced by treadmill exercise was --0.5 mv. for both groups and the range in the normal subgroup was --0.3 to --1.0 mv. No significant differences were found between the groups. We concluded that apparently healthy, asymptomatic men with acquired left bundle branch block can have considerable ST-segment depression in response to maximal treadmill testing and that their ST-segment response cannot be used to make diagnostic decisions about them.

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.

Cardiology. Reassessment of left bundle-branch block

In a population of patients who seek medical attention because of possible cardiac symptoms and are found to have left bundle-branch block, the vast majority have obvious cardiac disease, usually atherosclerotic or hypertensive. The prognosis in this group is poor and is a function of the underlying heart disease and not the conduction defect per se. The situation is distinctly different in a population of asymptomatic subjects whose conduction defect is discovered during routine electrocardiographic screening. In some of these individuals the conduction defect reflects previously unrecognized cardiac disease, but the majority have no other evidence of cardiovascular abnormality and approximately two thirds continue to do well over a relatively long follow-up period. It seems reasonable to reassure such patients regarding their prognosis, while at the same time maintaining careful follow-up. In situations where there is an important need to know for certain whether an individual has underlying cardiac disease, cardiac catheterization is indicated and should include coronary arteriography and hemodynamic measurements during exercise.

Short left coronary artery trunk as a risk factor in the development of coronary atherosclerosis. Pathological study

The relation between the length of the main left coronary artery and the degree of atherosclerosis in its branches was studied by postmortem examination in 204 subjects aged 20 to 90 years. The findings suggest that in cases with a short main left coronary artery the atherosclerotic lesions in the anterior descending and circumflex branches appear earlier, progress faster at higher levels of severity, and lead more frequently to myocardial infarction, than in cases with a long left coronary artery trunk. In cases over the age of 50 years, where disease is expected to have developed, it was shown that the degree of atherosclerosis in the left anterior descending and circumflex branches was inversely related to the length of the main left coronary artery. The correlation coefficients were -0-527 and -0-428, respectively, and in either case a test for zero correlations was significant (P less than 0-001). The possible changes in the haemodynamic and mechanical conditions associated with the variations of the anatomical pattern of the coronary arteries and their influence in the development of atherosclerosis are discussed. It is suggested that the length of the main left coronary artery is a congenital anatomical and possibly hereditary factor influencing the rate of development of atherosclerosis in the branches of the main left coronary artery.

Noninvasive myocardial imaging with potassium-43 and rubidium-81 in patients with left bundle branch block

Noninvasive myocardial imaging with potassium-43 and rubidium-81 has been used successfully to identify areas of infarction and exercise-induced ischemia as regions of decreased radioactivity. The image defects observed are believed to be due to a decreased radionuclide uptake in regions of myocardial scar or to heterogeneous myocardial accumulation of tracer as a result of regional ischemia. Of 27 patients with left bundle branch block studied with noninvasive imaging at rest and during exercise, 25 manifested at rest reduced radioactivity in the region of the interventricular septum. This pattern is similar to that seen in patients with anteroseptal myocardial infarction. Sixteen of the 27 patients underwent diagnostic coronary arteriography and left ventriculography. Only five of these patients had evidence of either previous infarction or significant obstructive coronary artery disease as assessed with clinical or angiographic criteria, or both. Although the image defect was routinely demonstrated at rest in patients with left bundle branch block, this defect was generally normalized or less distinct with exercise in patients with no anatomic heart disease. In contrast, a larger, more distinct or new image defect with exercise correctly identified the presence of significant obstructive coronary artery disease in patients with left bundle branch block. In the clinical application of noninvasive myocardial imaging, these image defects observed at rest can lead to the false pasitive radionuclide interpretation of anteroseptal myocardial infarction.

Length of main left coronary artery in relation to atherosclerosis of its branches. A coronary arteriographic study

The relation between the length of the main left coronary artery and the presence of atherosclerosis in its branches or the presence of complete left bundle-branch block was studied by selective coronary arteriography in 43 persons. The length of the main left coronary artery was found to be significantly shorter in patients with coronary atherosclerosis than in subjects without angiographic evidence of coronary artery disease. In patients with electrocardiographic evidence of complete left bundle-branch block, the length of the left main coronary artery was significantly shorter than that in both previous groups. In view of these findings, it is suggested that a short main left coronary artery should be considered as a congenital factor predisposing to the development of coronary artery disease. The possible mechanisms leading to atherosclerosis of the left coronary arterial branches in the presence of a short main trunk are discussed.

Left bundle branch block and coronary artery disease

This study tries the concept that left bundle-branch block (LBBB) connotes coronary artery disease (CAD). The findings indicate that prior studies both supporting of and in contradiction to the premise of a positive correlation have been biased by pre-selection of the patients reviewed. The data indicate, therefore, that LBBB is related to multiple entities. The major categories are CAD and/or hypertension myocardiopathy and aortic valvular disease. In addition, LBBB may develop during the acute phase of myocardial infarction. Its existence as a wholly benign entity has been documented as well. Further, this study adds still another group with LBBB. Six of the nine LBBB patients were female. Five of these, in spite of typical anginal histories, had no arteriographically demonstrable CAD. The absence of disease was surprising and the incidence of women with LBBB was greater than anticipated, thus providing some basis for suggesting that these women may be representative of still another group with LBBB. Further, this study supports the findings of Lewis et al by confirming an association between LBBB and a statistically shorter LCA mainstem (p less than 0.001).