Intraventricular conduction disturbances and coronary artery disease. Clinical, hemodynamic and angiographic study

Wideband myocardial perfusion pulse sequence for imaging patients with a cardiac implantable electronic device

PURPOSE

To develop a wideband cardiac perfusion pulse sequence and test whether it is capable of suppressing image artifacts in patients with a cardiac implantable electronic device (CIED), while not exceeding the specific absorption rate (SAR) limit (2.0 W/kg).

METHODS

A wideband perfusion pulse sequence was developed by incorporating a wideband saturation pulse to achieve a good balance between saturation of magnetization and SAR. Clinical standard and wideband perfusion MRI scans were performed back-to-back in a randomized order on 16 patients with a CIED undergoing clinical cardiac MRI. Two expert readers graded the artifact intensity and extent on a segmental basis using a 5-point Likert scale, where significant artifact was defined by a composite score. The variance in myocardial signal prior to tissue-enhancement was analyzed to quantify artifact-intensity. Whole-body SAR values computed by the MR scanner were read from the DICOM header. Either a paired t-test or Wilcoxon signed-rank test was performed to compare two groups.

RESULTS

While the mean whole-body SAR for a single-slice wideband perfusion scan (0.38 ± 0.08W/kg) was significantly (p < 0.05) higher than for a single-slice standard perfusion scan (0.11 ± 0.03W/kg), it was 81% below 2.0 W/kg. The mean variance in myocardial signal prior to tissue-enhancement was significantly (p < 0.001) higher for standard (422.6 ± 306.6 a.u.) than wideband (107.0 ± 60.9 a.u.). Among 105 myocardial segments, standard produced 19 segments (18%) that were deemed to have significant artifacts, whereas wideband produced only 3 segments (3%).

CONCLUSION

A wideband perfusion pulse sequence is capable of suppressing image artifacts induced by a CIED while not exceeding SAR at 2.0 W/kg.

Pacemaker stress echocardiography predicts cardiac events in patients with permanent pacemaker

PURPOSE

Noninvasive pacemaker stress echocardiography is a newly introduced method for the diagnosis of coronary artery disease in patients with a permanent pacemaker. The prognostic value of pacemaker stress echocardiography has not been studied.

SUBJECTS AND METHODS

We studied 136 patients (mean age 64+/-12 years) with a permanent pacemaker who underwent pacemaker stress echocardiography for evaluation of coronary artery disease. All patients underwent pacemaker stress echocardiography by external programming (pacing heart rate up to ischemia or target heart rate).

RESULTS

Thirty-one patients (23%) had normal study results. Ischemia was detected in 75 patients (55%). During a mean follow-up of 3.5+/-2.4 years, 35 deaths (26%) (20 the result of cardiac causes) and 2 nonfatal myocardial infarctions (1%) occurred. The annual cardiac death rate was 1.3% in patients without ischemia and 4.6% in patients with ischemia (P=.01). The annual all-cause mortality rate was 3.1% in patients without ischemia and 7% in patients with ischemia (P=.004). The presence of ischemia during pacemaker stress echocardiography was the strongest independent predictor of cardiac death (hazard ratio 4.1, confidence interval 1.2-14.5) and all-cause mortality (hazard ratio 2.7, confidence interval 1.2-6.0) in a multivariable model.

CONCLUSION

Myocardial ischemia during pacemaker stress echocardiography is an independent predictor of cardiac death and all-cause mortality in patients with a permanent pacemaker.

Importance of left anterior hemiblock development in inferior wall acute myocardial infarction

Of the 87 consecutive patients admitted with first inferior wall acute myocardial infarction, 17 had acute left anterior hemiblock. The appearance of left anterior hemiblock identified a specific group with more extensive coronary artery disease and suggests disease of the left anterior descending coronary artery.

Right bundle-branch block in coronary artery disease: a hemodynamic and angiographic study

Thirty-four patients with right bundle-branch block (RBBB) and coronary artery disease (CAD) (RBBB was not pre-existent to clinical development of CAD) and 52 consecutive CAD patients without conduction disturbances were studied and compared to verify whether the presence of RBBB implies more severe and extensive left ventricular myocardial damage as well as more severe CAD. The two groups did not differ either in age or in New York Heart Association functional class. The incidence or location of previous myocardial infarction (MI) was not different in the two groups. No significant differences were found in left ventricular volumes or ejection fraction. Higher end-diastolic left ventricular pressure and more severe and diffuse left ventricular wall asynergy were present in RBBB patients. At coronary arteriography, more severe involvement of the right coronary artery in CAD patients without conduction disturbances was the only significant finding. The group of patients with CAD and RBBB without MI showed significantly less involvement of the left anterior descending coronary artery and significantly more severe damage of the inferior wall of the left ventricle than the group with CAD without RBBB and MI. Patients with inferior wall MI and RBBB had more severe asynergy of the posterobasal region of the left ventricle than did patients with inferior wall MI without RBBB. The group of patients with anterior wall MI and RBBB had a higher left ventricular end-diastolic pressure, a lower left ventricular ejection fraction, and a greater extent of myocardial damage compared to similar patients of the control group. The groups with MI and RBBB had the same Gensini's score as similar groups without RBBB. (ABSTRACT TRUNCATED AT 250 WORDS)

Coronary angiographic significance of left anterior fascicular block during acute myocardial infarction

The clinical and angiographic significance of isolated left anterior fascicular block occurring during the early stage of acute myocardial infarction was studied in 141 consecutive patients who underwent cardiac catheterization before hospital discharge. Left anterior fascicular block occurred in 15 of the 62 patients with an anterior wall infarction and in 13 of the 79 with an inferior infarction. None of the clinical characteristics differed among patients with or without left anterior fascicular block. The number of coronary vessels with significant stenosis, the Friesinger and the Gensini scores for severity of stenosis and the ejection fraction were also similar in the two groups. Patients with left anterior fascicular block had more severe narrowing of the coronary artery supplying the infarct zone (88 +/- 21 versus 70 +/- 35%, p less than 0.001) and tended to have less developed collateral circulation (collateral score 0.7 +/- 0.8 versus 1 +/- 0.8, p = 0.10). A significant stenosis of the left anterior descending coronary artery was found as frequently in patients with as in those without left anterior fascicular block (64 versus 65%); 29% of the patients with inferior wall infarction and left anterior fascicular block had left anterior descending coronary artery stenosis compared with 47% of the patients without this conduction disturbance (no significant difference). When the infarction was located anteriorly, a significant stenosis of the proximal segment of the left anterior descending coronary artery was present in 47% of the patients with and in 45% of the patients without left anterior fascicular block.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

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.

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.

Reappraisal of the role of the diabetic state in coronary artery disease

Clinical and coronary arteriographic findings were evaluated in patients with angina pectoris who were considered not to have diabetes mellitus or to have chemical or clinical diabetes. Each of the three groups consisted of 100 consecutive referred patients. Neither the age of the patients nor duration of symptoms differed significantly among the groups. Hypertension, gout, and peripheral vascular disease were more frequent in the patients with clinical diabetes. There was no difference in serum cholesterol concentration among the groups, but plasma triglyceride levels and the frequency of type 4 hyperlipoproteinemia were significantly higher (p less than 0.01) in the chemical and clinical diabetic groups than in the nondiabetic patients. Coronary arteriographic observations indicated that the severity of the coronary arterial disease was greater in both diabetic groups than in nondiabetic patients. The difference in the coronary scores among the three groups of patients interacts to some extent with the triglyceride level, since a high score in the diabetic groups was noted only in the presence of an elevated tryglyceride concentration. The results indicate that the increased severity of coronary arterial disease in diabetic patients is not attributable to age, duration of symptoms, hypertension, type -4 hyperlipoproteinemia, or apparent severity of the glucose intolerance.

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.