Usefulness of contrast echocardiography for predicting the severity of angiographic coronary disease in non-ST-elevation myocardial infarction

Guidelines recommend coronary angiography in patients with non-ST-elevation myocardial infarction (NSTEMI) within 24 to 72 hours, a requirement that cannot always be met. The aim of this study was to evaluate the potential use of contrast echocardiography in prioritizing these patients by identifying those with NSTEMI and angiographically severe coronary artery disease (CAD). Echocardiography was performed before coronary angiography in 110 patients with NSTEMI (67 ± 12 years old, 31% women). Segmental myocardial perfusion and wall motion was scored using a 17-segment left ventricular model. CAD was assessed by quantitative coronary angiography. In the total study population, median troponin T level was 0.27 μg/L (0.13 to 0.86) and Thrombolysis In Myocardial Infarction risk score 3.1 ± 1.5. By quantitative coronary angiography 15% had normal coronary angiographic findings, whereas 1-, 2-, and 3-vessel disease were present in 35%, 27%, and 23%, respectively. Severe CAD (left main stem stenosis, 3-vessel disease, or multivessel disease including proximal stenosis in left anterior descending artery) was found in 42%. Number of segments with hypoperfusion increased with CAD severity from 4.1 ± 2.0 in patients with normal coronary arteries to 5.9 ± 2.4, 7.8 ± 3.5, and 10.4 ± 2.8 in patients with 1-, 2-, and 3-vessel disease, respectively (p<0.01). In multiple logistic regression analysis risk of severe CAD increased by 39% for every additional hypoperfused segment by echocardiography independent of wall motion abnormalities and Thrombolysis In Myocardial Infarction risk score. In conclusion, contrast echocardiography may be used for prediction of angiographic CAD severity in patients with NSTEMI awaiting coronary angiography.     

Acute effects of sublingual nifedipine on segmental and global left ventricular function in coronary artery disease; an angiographic study

In 12 patients with significant coronary artery disease (CAD) segmental and global left ventricular (LV) function was studied by quantitative cineventriculography before and 5 min after sublingual administration of 20 mg nifedipine (N). Significant increase of mean relative hemiaxes shortening of inferior (24 +/- 10%----38 +/- 13%) and apical (31 +/- 10%----42 +/- 14%) wall segments, as well as improvement of ejection fraction (61 +/- 14%----75 +/- 14%), mean circumferential fiber shortening velocity (1.05 +/- 0.46 ccf/s----1.41 +/- 0.47 ccf/s) and end-systolic volume (57 +/- 26 ml----37 +/- 27 ml) of the LV were found after administration of N. The highest increase of segmental contraction (28 +/- 11%----44 +/- 16%; p less than 0.001) was noted in 20 noninfarcted wall segments, perfused by significantly stenosed coronary arteries. No significant improvement could be detected in 6 infarcted segments. A second group consisting of 12 patients with CAD showed a significant reduction of the aortic end-diastolic pressure (89 +/- 9 mm Hg----79 +/- 7 mm Hg; p less than 0.001) but no significant change of isovolumic contractility indices and heart rate was observed after N administration. The study suggests that acute improvement of LV function, found 5 min after sublingual administration of N, is mainly due to improved contraction of ischemic myocardial wall segments. Among different possible reasons for this improvement LV afterload reduction after N administration seems to be the most important one.     

Cardiokymography during exercise testing: A new device for the detection of coronary artery disease and left ventricular wall motion abnormalities

The cardiokymograph (CKG) is a device that has been shown to reflect left ventricular (LV) wall motion abnormalities. Its accuracy in detecting coronary artery disease (CAD) during treadmill exercise testing was assessed in 204 consecutive patients undergoing coronary arteriography. Of the 188 patients with a technically adequate CKG, 146 (78%) had significant CAD. The sensitivity and specificity were similar for both the exercise electrocardiogram (ECG) (66% and 86%, respectively) and the exercise CKG (73% and 95%, respectively). An abnormal exercise CKG was significantly more common In patients with 3-vessel CAD than in those with 1-vessel disease (97% versus 52%, respectively;p < 0.001) and in patients with left anterior descending disease than in those without (85% versus 26%, respectively; p < 0.001). Seventy patients showed both an abnormal exercise ECG and CKG; all had CAD and 86% had multivessel CAD. Forty-eight patients demonstrated a normal exercise ECG and CKG; 29% had CAD but only 6% had multivessel CAD. Among 55 patients who had simultaneous exercise radionuclide ventriculography, new septal or apical wall motion abnormalities were found in 79% (23 of 29) of patients with an abnormal CKG compared with 19% (5 of 26) of patients with a normal CKG (p < 0.001). Thus, the CKG during exercise testing accurately reflects LV wall motion abnormalities and can be used to improve the diagnostic accuracy of exercise testing as an additional marker of myocardial ischemia.     

Regional left ventricular systolic function in patients with segmental early relaxation and single-vessel coronary artery disease

The purpose of this study was to determine whether systolic function is compromised in segments of the left ventricle that manifest early relaxation and are supplied by a diseased coronary artery. Regional fractional area of shortening (FAS) was evaluated from resting ventriculograms of 24 patients. Nine patients had no cardiac disease or segmental early relaxation (SER) and served as controls. Fifteen patients had single-vessel coronary artery disease (60% to 95% diameter stenosis of the left anterior descending coronary artery). Among these 15 patients, seven had no evidence of SER and eight had SER localized to the anterior wall. In patients with coronary disease and SER, and FAS of the anterolateral segment, 1.30 +/- 0.08, was greater than either controls, 1.07 +/- 0.12 (p less than 0.01) or patients with coronary disease but no SER, 1.03 +/- 0.19 (p less than 0.01). Among patients with coronary disease and SER, the FAS of the anterolateral segment was greater than the corresponding diaphragmatic segment (1.30 +/- 0.08 vs 0.97 +/- 0.12) (p less than 0.001). There was no difference in the FAS between these two segments in either controls or in patients with coronary disease, but without SER. These results indicate that SER of the anterior wall in patients with disease of the left anterior descending coronary artery is associated with enhanced systolic function of the anterolateral region. This observation is incompatible with the concept that ischemia is an underlying mechanism of SER.     

Prognostic implications of regional hyperkinesia and remote asynergy of noninfarcted myocardium

To determine the clinical significance of regional hyperkinesia and remote asynergy of noninfarcted areas in patients with a first acute myocardial infarction (AMI), 2-dimensional echocardiography was performed in 113 consecutive patients within 12 hours after admission to the coronary care unit. In 98 patients (87%) all segments of the left ventricular wall were recorded. Infarct-associated asynergy was anterior in 63 and inferior in 35 patients. Regional hyperkinesia was present in 66 patients (67%)--44 of 63 with anterior (69%) and 22 of 35 with inferior (63%) infarcts--and was more frequently seen in patients with 1- and 2-vessel coronary artery disease (CAD) than in patients with 3-vessel CAD (87 and 72% vs 25%, p less than 0.001). In contrast to enzymatic infarct size, absence of regional hyperkinesia was significantly associated with a higher left ventricular wall motion score (p less than 0.01). Twenty patients died within 30 days after onset of AMI; in 15 (75%) regional hyperkinesia was absent. Absence of regional hyperkinesia, especially in anterior infarcts, was associated with a high mortality rate (13 of 19 patients [68%]). Remote asynergy, i.e., not adjacent to the infarct area and supposed to be related to another vascular region, was present in 17 of 98 patients (17%)--11 of 63 with anterior (17%) and 6 of 35 with inferior (17%) infarcts. Remote asynergy was present only in patients with multivessel CAD and was significantly related to a higher wall motion score (p less than 0.001), but not to enzymatic infarct size.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term beneficial effects of PTCA on segmental early relaxation in disease of the left anterior descending coronary artery

The relationship between regional left ventricular (LV) motion and global pressure relaxation of the left ventricle remains unclear. To clarify the recent concept of segmental early relaxation in coronary artery disease, the authors investigated two groups of patients. In group I, all 12 patients (mean age 47 +/- 7 years) exhibited evidence of a normal heart after an extensive investigation. In group II, 25 patients (55 +/- 7 years) presented an isolated stenosis of the left anterior descending coronary artery, and they underwent a hemodynamic investigation before and after (six to nine months) a durable successful percutaneous transluminal coronary angioplasty (PTCA). After all conventional hemodynamic measurements had been done, a quantitative frame-by-frame analysis of left ventricular wall motion was conducted. The authors' method is derived from that of Ingels, applying to LV cineangiograms filmed in 30 degrees right anterior oblique view at a 50 frames/second rate. Thus segmental wall motion is analyzed in terms of amplitudes (%), velocities of shortening and lengthening in circumferences/second (circ/sec), and times of events (%). Statistical results took into account the reproducibility of the method. Main results regarding the control state of group II consisted of an asynergic motion of the anterior region taking place from end systole to early diastole: 1. Early end of contraction in anterior segments (% of systolic time interval: 88 +/- 14% vs 96 +/- 6% in group I, p less than 0.001) 2. Asynchronism at end systole (maximal velocity of shortening - 0.4 +/- 2.3 circ/sec in anterior segments vs 0.05 +/- 1.9 in inferior segments, p less than 0.02) 3. An early but poor outward anterior wall motion (anterior lengthening at 0.04 sec after the end of ejection 2.9 +/- 10% in group II versus 5.4 +/- 7.2% in group I, p less than 0.05) These abnormalities are strongly correlated with a significant impairment of peak negative diastolic pressure/diastolic time (dP/dt) (1500 +/- 400 mmHg. sec-1 vs 1850 +/- 410 in group I, p less than 0.02). Long-term beneficial effects of PTCA in group II were characterized by an almost complete normalization, both asynergy and relaxation taking place back within the normal range. The authors conclude that in this kind of patient, peak negative dP/dt could be an index of an asynergic segmental motion, this one being correctly analyzed and quantified on LV cineangiograms with our method.     

Prognostic importance of wall motion abnormalities in patients with ischemic cardiomyopathy and an implantable cardioverter-defibrillator

Patients with extensive regional wall motion abnormalities are predisposed to development of ventricular tachyarrhythmia. The prognostic effect of this in patients with an implantable cardioverter-defibrillator (ICD) and coronary artery disease (CAD) is not known. Echocardiographic left ventricular systolic indexes, wall motion score index (WMSI), and extent of regional akinesia in 140 patients (65 +/- 10 years old; 92% men) with an ICD and CAD were studied. Arrhythmic events requiring ICD therapy and causing death (n = 41, 29%) were recorded over a mean follow-up of 1.4 +/- 0.8 years. Left ventricular basal fractional shortening, ejection fraction, global WMSI, and extent of akinesia, especially in the inferoposterior regions of a right coronary artery territory, were univariate predictors (all p values <0.05). Global WMSI (hazard ratio 2.18, 95% confidence interval 1.03 to 4.65, p = 0.04) and fractional shortening (hazard ratio 0.93, 95% confidence interval 0.88 to 1.00, p = 0.04) were multivariate predictors. Global WMSI (p = 0.04) and > or =2 right coronary region akinetic segments (p = 0.05) provided incremental risk prediction to left ventricular ejection fraction in a global risk-assessment model (chi-square p = 0.001). Presence of right coronary region akinesia better identified those at increased risk of events (p = 0.02) compared with the presence of left anterior descending region akinesia (p = 0.2), independent of systolic function. In conclusion, global WMSI and left ventricular basal fractional shortening were important additional risk predictors of ICD events in CAD. Global WMSI and right coronary region inferoposterior akinesia provided independent and incremental risk assessment to left ventricular ejection fraction and improved identification of those at increased risk of ICD-related events in patients with ischemic cardiomyopathy.     

Catheter-based electromechanical mapping to assess regional myocardial function: a comparative analysis with transthoracic echocardiography.

Recent studies using a nonfluoroscopic three-dimensional left ventricular mapping system showed considerable changes in voltage potentials and mechanical activity detected in ischemic and infarcted myocardial regions with mechanical dysfunction. This study examined the electromechanical characteristics in relation to regional wall motion assessed by echocardiography in patients with coronary artery disease. A 12-segment model of mapping (apical, mid, basal of septal, anterior, lateral, and inferior/posterior segments) was compared to echo wall motion score in 74 patients (836 segments). Unipolar voltage and local endocardial shortening signals were distinguished according to graded echo segmental rest scores (0 = normal, 1 = mild hypokinesis, 2 = moderate hypokinesis, 3 = severe hypokinesis, 4 = akinesis). Results show a significant difference in voltage potentials and shortening values in groups distinguished according to echocardiography motion score. The average voltage potentials and shortening values were highest in myocardial segments with normal or slightly reduced contractility and lowest in myocardial segments with moderate to severely impaired contractility scores (voltage: 12.3 +/- 5.0, 12.1 +/- 5.3, 10.7 +/- 5.4, 8.7 +/- 3.9, 7.1 +/- 3.0 mV, P = 0.0001; local shortening: 9.7 +/- 6.5, 8.4 +/- 5.9, 8.0 +/- 5.4, 5.6 +/- 6.3, 5.1 +/- 4.6%, P = 0.0001 in regions with segmental scores of 0, 1, 2, 3, 4 by echo, respectively). Using receiver-operating curve calculations, the area under the curve was 0.72 +/- 0.06 (voltage) and 0.67 +/- 0.05 (local shortening) without a significant difference between the two curves. The 90% thresholds for defining preserved vs. impaired contractility were 12.8 and 5.6 mV for voltage and 12.6% and 1.6% for local shortening. We conclude that electromechanical mapping correlates with regional changes in wall motion scores assessed by echo, showing a gradual proportional decrease in measured voltage and shortening signals in segments with impaired function.     

Influence of the angiocardiographic severity of ischemic heart disease on QTc duration

The influence of severity of coronary artery disease (CAD) on the duration of corrected electrical systole (QTc) and the prognostic value to predict sudden death of this index were retrospectively evaluated in 123 non-consecutive patients with history of stable angina who underwent cardiac catheterization. Fifteen patients had no angiographic evidence of CAD (O-V group). The 108 patients with a greater than or equal to 70% luminal diameter narrowing of a major coronary artery were further subdivided: 23 patients had 1-vessel (1-V group), 40 patients had 2-vessel (2-V group) and 45 had 3-vessel (3-V group) coronary artery disease; 26 patients showed normal left ventricular (LV) wall motion (A group), 57 patients showed asynergic contraction of 1 or 2 LV areas (B group) and 25 patients showed 3 or more areas of asynergy and/or aneurysm. Sixty-one patients had a previous myocardial infarction (MI). QT interval, calculated in the lead where it was longer, on 12-lead resting electrocardiograms recorded at a paper speed of 25 mm/sec, was corrected by the formula: QTc = QT/square root R-R. The follow-up was performed by telephone. At the time of angiography there was no significant difference in QTc duration between the different groups according to the severity of CAD (O-V, 1-V, 2-V and 3-V groups). Patients showing three or more areas of abnormal segmental wall motion and/or aneurysm (C group) had a significantly longer QTc (p less than 0.05) than patients with normal LV wall motion (A group).(ABSTRACT TRUNCATED AT 250 WORDS)     

Anatomic and functional significance of a hypotensive response during supine exercise radionuclide ventriculography

The significance of a decline in systolic blood pressure (BP) during supine exercise was examined in 820 patients who underwent both supine exercise gated equilibrium radionuclide ventriculography and coronary angiography. Twenty-seven patients, 3% of the study population, had a decrease in systolic BP at peak exercise of more than 10 mm Hg from the systolic BP at rest. Other indicators of ischemia--angina, ST-segment depression, a decrease in ejection fraction and wall motion abnormality during exercise--were present frequently but not uniformly in these patients. Although most patients had a decline in ejection fraction and a new wall motion abnormality with exercise, 4 patients had an increase in ejection fraction with exercise without any regional wall motion abnormalities. Coronary angiography in the 27 patients with systolic hypotension demonstrated severe coronary artery disease (CAD). Twenty-two patients (81%) had 3-vessel or left main CAD. Twenty of these 22 patients with 3-vessel CAD had at least 2 arteries with 90% or more diameter stenoses. Systolic hypotension during supine exercise radionuclide angiography is infrequent, usually associated with evidence of global and regional left ventricular dysfunction, and a marker of very severe CAD.     

The effects of Valsalva maneuver on global and segmental left ventricular function in presence and absence of coronary artery disease

To determine the effects of the Valsalva maneuver on global and regional left ventricular function, single-plane left ventriculograms were performed in the 30-degree right anterior oblique projection in 50 patients during normal breath holding and during the late strain phase of the Valsalva maneuver. Thirty-one patients had significant coronary artery disease (greater than 70% luminal narrowing in a major coronary artery). Ventriculograms were analyzed for determination of ejection fraction, end-diastolic, and end-systolic volumes. Regional wall motion was analyzed by a chord method of calculating segmental fractional shortening. Ejection fraction increased significantly in the entire group of patients (62 +/- 16% to 70 +/- 19%, p less than 0.0001), while both end-diastolic (105 +/- 33 cc to 88 +/- 34 cc, p less than 0.0001) and end-systolic volumes (43 +/- 29 cc to 30 +/- 29 cc, p less than 0.0001) showed striking reductions with Valsalva maneuver. Patients without significant coronary disease usually exhibited global augmentation in left ventricular function, while those with coronary disease often exhibited only segmental improvement. This augmentation appeared to be dependent on the patency of the supplying coronary vessel.     

Low-dose dobutamine in patients with acute myocardial infarction identifies viable but not contractile myocardium and predicts the magnitude of improvement in wall motion abnormalities in response to coronary revascularization

To assess the effects of coronary revascularization on viable but noncontractile myocardium, we examined 21 patients with a documented anterior acute myocardial infarction who had a significant improvement in wall motion abnormality evaluated by two-dimensional echocardiography in the infarct-related artery in response to low-dose dobutamine infusion. All patients had a significant residual stenosis in the infarct-related artery. In response to low-dose dobutamine, there was a marked improvement in contractility in the infarct-related area segments and this was reflected by a decrease in echocardiographic score index from 1.5 +/- 0.15 to 1.09 +/- 0.08 (p = 0.0001). Of these 21 patients, 13 underwent successful revascularization: 10 had percutaneous transluminal coronary angioplasty (PTCA) and three had coronary artery bypass grafts (CABG) (group I). Eight patients received medical therapy only (group II). At 40 +/- 15 days of follow-up, both groups had improvement in their segmental wall motion abnormalities. However, the improvement in group I was greater than that in group II, 1.1 +/- 0.13 and 1.35 +/- 0.1, respectively (p = 0.0002). We conclude that: (1) low-dose dobutamine infusion may identify viable but noncontractile myocardium in patients with acute myocardial infarction and (2) in these patients revascularization causes a greater improvement in left ventricular function over time when compared with a nonrevascularized group.     

Relation of ultrasonic tissue characterization with integrated backscatter to contractile reserve in patients with chronic coronary artery disease

BACKGROUND: Previous studies have shown that viable but stunned myocardium displays contractile reserve and exhibits cardiac cycle-dependent variations of integrated backscatter (CVIB), whereas infarcted myocardium does not. HYPOTHESIS: This study was designed to clarify whether assessment of the acoustic properties of the myocardium can predict contractile reserve in patients with chronic coronary artery disease (CAD). METHODS: In all, 21 patients with chronic CAD and 19 normal control subjects were studied. The magnitude of CVIB of the myocardium was measured in the basal and mid segment of the anterior septum and posterior wall of the left ventricle, using a real-time, two-dimensional integrated backscatter imaging system. The results were compared with the percent systolic wall thickening and the wall motion before and after revascularization. The wall motion was graded as normal, hypokinetic, or akinetic, and contractile reserve was considered present when an akinetic or hypokinetic segment improved after revascularization. RESULTS: The average magnitude of CVIB was lower among dysfunctional segments of CAD than among normal segments of controls (3.73 +/- 1.71 vs. 6.35 +/- 0.69, p < 0.001). Of the 77 segments examined, 38 showed reversible dysfunction. Before revascularization, percent systolic wall thickening was similar among segments showing contractile reserve compared with those with persistent dysfunction myocardium (17.97 +/- 8.41 vs. 16.83 +/- 6.37%, p = 0.19), and the mean CVIB was significantly greater in segments with than in those without contractile reserve (4.73 +/- 1.47 vs. 2.75 +/- 1.31, p < 0.001). The CVIB above 3 dB before percutaneous transluminal coronary angioplasty predicted segments with contractile reserve with a sensitivity and specificity of 84.2 and 79.5%, respectively. CONCLUSIONS: Cardiac cycle-dependent variations of integrated backscatter reflected myocardial contractility and functional capacity of the myocardium. They predicted segmental contractile reserve in patients with CAD.     

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 (greater than or equal to 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.     

Correlation of the exercise ST/HR slope with anatomic and radionuclide cineangiographic findings in stable angina pectoris

A rate-related change in ST-segment depression with exercise (ST/HR slope) of 6.0 microV/beat/min or more has been proposed as an accurate predictor of 3-vessel coronary artery disease (CAD). To further assess the accuracy and functional correlates of this method, exercise electrocardiograms were compared with radionuclide rest and exercise left ventricular (LV) ejection fraction (EF) and angiography in 35 patients with stable angina. The ST/HR slope was significantly increased in patients with 3-vessel CAD. An ST/HR slope of 6.0 or more identified 3-vessel CAD with a sensitivity of 89% and specificity of 88%. The predictive value for 3-vessel CAD was 73% owing to the presence of 3 false-positive slopes. The patients from whom these slopes were derived had functionally severe 2-vessel CAD, with an average decrease in exercise LVEF of 13%. Two of these 3 had additional left main CAD and the third has unsuspected additional aortic regurgitation. For the entire group, the exercise ST/HR slope was linearly related to the exercise change in LVEF (r = -0.55, p less than 0.001). Mean exercise change in LVEF for stable angina patients with ST/HR slopes of 4.5 or more was significantly different from that for patients with lower ST/HR slopes (-12 +/- 1% vs + 2 +/- 2%, p less than 0.0001). Thus, the ST/HR slope is both sensitive and specific for the identification of 3-vessel CAD, and high ST/HR slopes in patients with less extensive anatomic disease may predict functionally severe ischemia.     

Prevalence of high-risk thallium-201 scintigraphic findings in left main coronary artery stenosis: comparison with patients with multiple- and single-vessel coronary artery disease

To determine the prevalence of high-risk thallium-201 (Tl-201) scintigraphic findings in patients with left main (LM) coronary artery disease (CAD), quantitative exercise Tl-201 scintigrams were analyzed in 295 consecutive patients with angiographic (greater than or equal to 50% stenosis) CAD, of which 43 (14%) had greater than or equal to 50% LM stenosis. A high-risk scintigram was defined as one that demonstrated (1) a LMCAD scintigraphic pattern (greater than or equal to 25% homogeneous decrease in Tl-201 activity in the middle and upper septal and posterolateral walls on the 45 degree left anterior oblique projection); (2) abnormal Tl-201 uptake or washout in multiple vascular scan segments indicative of multivessel disease; and (3) increased lung Tl-201 uptake on the initial anterior projection image. Of the 43 patients with LMCAD, 41 (95%) had an abnormal scintigram. Thirty-three (77%) had 1 or more high-risk scintigraphic findings, including 29 (67%) with a multivessel CAD scan pattern, of which 6 (14%) demonstrated a typical LMCAD pattern; and 18 (42%) with abnormal lung Tl-201 uptake. The prevalence of a high-risk scintigram in patients with LMCAD was significantly greater than that in 53 patients with 3-vessel disease (58%) (p = 0.05), 99 patients with 2-vessel disease (60%) (p = 0.04) and 100 patients with 1-vessel disease (41%) (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Usefulness of topography of coronary calcium by electron-beam computed tomography in predicting the natural history of coronary atherosclerosis

Electron-beam computed tomography (EBCT) allows for accurate noninvasive detection and quantification of coronary calcium that is representative of underlying atherosclerotic disease. The present study quantitatively analyzes the topography and establishes the natural history of coronary calcium in patients with variable degrees of coronary atherosclerosis. EBCT was performed in 330 consecutive patients aged 56 +/- 12 years (70% men) with recent (<3 months) onset of signs or symptoms of coronary artery disease (CAD) or who were evaluated because of a presumed high risk. Total calcium scores, computed by the Agatston method, were positive in 269 patients (82%) (mean age 58 +/- 11 years, 73% men). These patients were classified into 4 groups, with total calcium scores ranging between 1 and 30, >30 and 100, >100 and 400, and >400, respectively. The presence and amount of calcium was additionally assessed in 10 major segments of the coronary arterial tree, including the major coronary arteries. Of the 72 patients with calcium of only 1 of the major coronary arteries, the left anterior descending coronary artery was involved in 39 patients (54%) and the right coronary artery in 18 patients (25%). Left main stem calcium was observed in only 10 of 139 patients (7%) with 1- or 2-vessel calcium and in 17 of 77 patients (23%) with 3-vessel calcium. Calcium was consistent most frequently in the proximal left anterior descending coronary artery, followed by the proximal left circumflex and right coronary artery segments. A significant decrease of frequency and amount of calcium from the proximal to distal segments was observed in the left coronary system but not in the right coronary artery, where the distribution was more even. With increasing total calcium scores, segmental scores in the more distal segments were enhanced, but the increase was most pronounced in the proximal segments and particularly in the proximal left anterior descending coronary artery. EBCT-derived coronary calcium shows an axial distribution that appears comparable to that of atherosclerotic lesions observed in pathologic and angiographic studies, highlighting the potential role of EBCT for studying the natural history of CAD.     

Localization of coronary artery narrowings by applying R-wave amplitude correction to exercise-induced ST depression in angina pectoris and single-vessel coronary artery narrowing

This study investigated whether coronary artery narrowings can be localized by applying R-wave amplitude correction to exercise-induced ST depression in multiple unipolar precordial lead electrocardiography using 20 electrodes covering the left chest wall. Ten normal subjects and 29 patients with stable angina pectoris and single-vessel coronary artery narrowing (greater than or equal to 75% luminal diameter stenosis in only 1-vessel) participated. Of the 29 patients, 5 had left main coronary artery disease (CAD), 14 had left anterior descending CAD, 4 had right CAD and 6 had left circumflex CAD. The exercise-induced ST depression with R-wave amplitude correction was defined as the exercise-induced ST depression divided by the R-wave amplitude. The 20 points of the lead system were divided into 4 areas: the left main, left anterior descending, right and left circumflex coronary arteries. Coronary artery narrowing was supposed to be in an artery corresponding to the area where the maximal value of the exercise-induced ST depression with and without R-wave amplitude correction was situated. By applying R-wave amplitude correction, the diagnostic ability of localization of coronary artery narrowings was improved significantly from 52% to 86% (p less than 0.005). In particular, localization of the left main coronary artery narrowing was correctly diagnosed in 100% (5 of 5) of angina pectoris patients with left main CAD.     

Clinical and angiographic profile and follow-up of myocardial bridges: a study of 21 cases

Myocardial bridging describes an angiographic entity, which is any degree of systolic narrowing of a coronary artery observed in at least one angiographic projection. Among the cineangiograms of 3200 patients reviewed, there were 21 cases (19 males) of myocardial bridges--incidence of 0.6 percent. Of these, seven had hypertrophic cardiomyopathy, six had atherosclerotic coronary artery disease and remaining eight had no evidence of either. All 21 patients had myocardial bridges in proximal or mid left anterior descending coronary artery. In addition, one case of hypertrophic cardiomyopathy had whole posterior descending coronary artery under a myocardial bridge. Another case of hypertrophic cardiomyopathy had a short normal segment of 5 mm inside a long myocardial bridge of 35 mm (tandem myocardial bridges). The length of the bridges varied from 10 to 35 mm (mean 24.5 +/- 4.5 mm) and diameter stenosis during systole varied from 40-90 percent (mean 70 +/- 8%). Two patients had large saccular coronary aneurysms proximal to the muscle bridge. Four of the eight patients who had neither hypertrophic cardiomyopathy nor coronary artery disease presented with acute anterior wall myocardial infarction and three of them had regional wall motion abnormality of left descending territory. Of the six patients who had coronary artery disease, one had 60 percent left descending artery lesion and two had recanalized segments proximal to the bridge. Five of the above six patients had significant stenosis of other coronary vessels. Four patients were lost to follow-up (mean period 3.4 +/- 2 years). In the coronary artery disease group, one patient underwent coronary artery bypass graft surgery for 3-vessel disease including graft to left descending artery and one developed inferior wall myocardial infarction. The patients in the hypertrophic cardiomyopathy group and "no hypertrophic cardiomyopathy-no coronary artery disease" group were free of events at last follow-up. Long-term prognosis of isolated myocardial bridges appears to be excellent. Degree of systolic narrowing or length of myocardial bridge does not correlate with event rates on follow-up.     

Comparison of specificity of quantitative myocardial contrast echocardiography for diagnosis of coronary artery disease in patients with versus without diabetes mellitus

Impaired coronary flow reserve is widely reported in diabetes mellitus (DM) but its effect on myocardial contrast echocardiography (MCE) is unclear. We sought to identify whether DM influences the accuracy of qualitative and quantitative assessment of coronary artery disease (CAD) using MCE in 83 patients who underwent coronary angiography (60 men, 27 with DM; 56 +/- 11 years;). Destruction replenishment imaging was performed at rest and after combined dipyridamole-exercise stress testing. Ischemia was identified by the development of new wall motion abnormalities, qualitative MCE (new perfusion defects apparent 1 second after flash during hyperemia), and quantitative MCE (myocardial blood flow reserve <2.0 in the anterior circulation). Qualitative and quantitative assessment of perfusion was feasible in 100% and 92% of patients, respectively. Significant left anterior descending coronary stenosis (>50% by quantitative angiography) was present in 28 patients (including 8 with DM); 55 patients had no CAD (including 19 with DM). The myocardial blood flow reserve was reduced in patients with coronary stenosis compared with those with no CAD (1.6 +/- 1.1 vs 3.8 +/- 2.5, p <0.001). Among patients with no CAD, those with DM had an impaired flow reserve compared with control patients without DM (2.4 +/- 1.0 vs 4.5 +/- 2.8, p = 0.003). In conclusion, DM significantly influenced the quantitative, but not the qualitative, assessment of MCE, with a marked reduction in specificity in patients with DM.