High-grade Coronary Artery Stenosis Research Articles

Coronary Artery Bypass Grafting: A Clinical Overview.

Coronary artery bypass grafting remains a viable and successful option for treating high-grade coronary artery stenosis. The postoperative recovery is individual for each patient, but when following long-standing guidelines and physician orders, outcomes are generally positive.

Economic Considerations for Coronary CT Angiography

In recent years, coronary CT angiography (CCTA) has emerged has a noninvasive anatomic imaging modality that demonstrates high diagnostic performance to detect and exclude high-grade coronary artery stenosis. Proponents of CCTA have advocated its use as an effective alternative to functional stress imaging, while critics have maintained that the benefits of CCTA use remain unproven and may promote unnecessary “layering” of imaging studies on top of conventional stress testing. In this review, we consider the clinical and economic data related to CCTA to date, and suggest future studies that may clarify the role of CCTA in daily clinical evaluation of patients with suspected or known coronary artery disease.

Quantitative Whole Heart Stress Perfusion CT Imaging as Noninvasive Assessment of Hemodynamics in Coronary Artery Stenosis

To quantify differences in regional myocardial perfusion in coronary artery stenosis by the use of dual source computed tomography (DSCT) in an animal model. In 5 pigs, an 80% stenosis of the left anterior descending artery was successfully induced by partial balloon occlusion (ischemia group). Five animals served as control group. All animals underwent contrast enhanced whole heart DSCT (Definition Flash, Siemens, Germany) perfusion imaging using a prototype electrocardiogram -triggered dynamic scan mode. Imaging was performed at rest as well as under stress conditions during continuous infusion of adenosine (240 mg/kg/min). For contrast enhancement 60 mL Iopromide 300 (Ultravist 300, Bayer-Schering Pharma, Berlin, Germany) were injected at a rate of 6 mL/s. Myocardial blood flow (MBF), first pass distribution volume, and intravascular blood volume were volumetrically quantified. In the control group MBF increased significantly from 98.2 mL/100 mL/min to 134.0 mL/100 mL/min if adenosine was administered (P = 0.0153). There were no significant differences in the perfusion parameters comparing the control and ischemia group at rest. In the ischemia group MBF under stress was 74.0 +/- 21.9 mL/100 mL/min in the poststenotic myocardium and 117.4 +/- 18.6 mL/100 mL/min in the remaining normal myocardium (P = 0.0024). DSCT permits quantitative whole heart perfusion imaging. As this technique is able to show the hemodynamic effect of high grade coronary artery stenosis, it exceeds the present key limitation of cardiac computed tomography, which currently only allows a morphologic assessment of coronary artery stenosis.

Clinical characteristics of patients with obstructive coronary lesions in the absence of coronary calcification: an evaluation by coronary CT angiography

Background:Multidetector CT allows detection of coronary artery calcium and, after contrast injection, visualisation of the coronary artery lumen. It is commonly assumed that the absence of coronary calcification makes the...

Diagnostic accuracy and image quality of cardiac dual-source computed tomography in patients with arrhythmia

Background Cardiac multi-detector computed tomography (MDCT) permits accurate visualization of high-grade coronary artery stenosis. However, in patients with heart rate irregularities, MDCT was found to have limitations. Thus, the aim of the present study was to evaluate the diagnostic accuracy of a new dual-source computed tomography (DSCT) scanner generation with 83 ms temporal resolution in patients without stable sinus rhythm. Methods 44 patients (31 men, mean age 67.5 ± 9.2 years) without stable sinus rhythm and scheduled for invasive coronary angiography (ICA) because of suspected ( n = 17) or known coronary artery disease (CAD, n = 27) were included in this study. All patients were examined with DSCT (Somatom Definition ™, Siemens). Besides assessment of total calcium score, all coronary segments were analyzed with regard to the presence of significant coronary artery lesions (> 50%). The findings were compared to ICA in a blinded fashion. Results During CT examination, heart rhythm was as follows: 25 patients (57%) atrial fibrillation, 7 patients (16%) ventricular extrasystoles (two of them with atrial fibrillation), 4 patients (9%) supraventricular extrasystoles, 10 patients (23%) sinus arrhythmia (heart rate variability > 10 bpm). Mean heart rate was 69 ± 14 bpm, median 65 bpm. Mean Agatston score equivalent (ASE) was 762, ranging from 0 to 4949.7 ASE. Prevalence of CAD was 68% (30/44). 155 segments (27%) showed “step-ladder” artifacts and 28 segments (5%) could not be visualized by DSCT. Only 70 segments (12%) were completely imaged without any artifacts. Based on a coronary segment model, sensitivity was 73%, specificity 91%, positive predictive value 63%, and negative predictive value 94% for the detection of significant lesions (≥ 50% diameter stenosis). Overall accuracy was 88%. Conclusions In patients with heart rate irregularities, including patients with atrial fibrillation and a high prevalence of coronary artery disease, the diagnostic yield of dual-source computed tomography is still hampered due to a high number of segments with “step-ladder” artifacts.

New Frontiers in the Evaluation of Cardiac Patients for Noncardiac Surgery

New Frontiers in the Evaluation of Cardiac Patients for Noncardiac Surgery

Koronarkalkquantifizierung und Koronarangiographie mittels Mehrzeilendetektorspiral-CT - Klinische Erfahrungen

To report our clinical experience in calcium scoring and coronary angiography with multislice computer tomography (MSCT). Cardiac four-row MSCT (Siemens, Volume Zoom, Erlangen, Germany) was performed in 60 patients, comprising 45 patients without known coronary vessel disease (CVD) and falling in an intermediate risk (group I) by calcium scoring, and 15 patients with multivessel disease by the combination of calcium scoring and MSCT coronary angiography (group II). Group I underwent analysis of risk factors as well as patient management in the form of risk profile modulation, indication for invasive selective coronary angiography (SCA) and supplemental myocardial diagnostic evaluation (e. g., SPECT). Agatston and volume scores (Virtuoso, Siemens, Erlangen, Germany) were calculated for calcium scoring. Group II had the calcium scoring and diagnostic accuracy of MSCT in detecting coronary artery stenosis evaluated according to established American Heart Association (AHA) criteria. SCA was used as gold standard. In group I, calcium scoring was positive in 27/45 (60 %) patients, with 14/27 (52 %) consecutively referred to SCA and 2/27 (7 %) to SPECT. SCA revealed significant coronary stenosis (> 60 %) in 5/27 (19 %) patients and SPECT detected myocardial ischemia in 0/2 patients. Patients with obstructive coronary vessel disease showed a significantly increased calcium score of > 300 together with a high risk profile. Patients with negative calcium score showed significantly less risk factors (p < 0.05). The use of calcium scoring in therapeutic procedures in the form of increased modulation of risk factors was documented in 21/45 (47 %) patients. In group II, sensitivity, specificity and diagnostic accuracy for the detection of high grade coronary artery stenosis were 64 %, 99 % and 96 %, and the Agatston and Volume scores were 333 +/- 123 and 334 +/- 136, respectively. MSCT can be applied as risk profile module for coronary screening of patients with intermediate risk. As non-invasive alternative for the evaluation of coronary vessel disease, it can be useful in some cases by providing additional information.

Increased leukocyte activity as a predictor for flow-limiting coronary lesions in patients with angina pectoris

Myocardial ischemia initiates an acute inflammatory response, in which polymorphonuclear leukocytes (PMNs) are major participants. We investigated whether increased PMN activity in the peripheral blood is a marker for high-grade coronary artery stenosis in patients with angina pectoris. PMN activity was examined in 45 patients by measuring the luminol-dependent chemiluminescence (CL) response of the peripheral blood upon addition of phorbol myristate acetate (PMA). The CL of patients with angiographic filling delay was 1.6-fold higher than in patients without delay (480±54 vs. 302±33 counts/PMN, P<0.01). The CL of patients with a filling delay of the left anterior descending artery (LAD) was 1.7-fold higher than in patients without an LAD filling delay (537±79 vs. 317±27 counts/PMN, P<0.01). With the CL cut-off at 400 counts/PMN, the sensitivity and specificity for detecting an angiographic filling delay of the LAD were 69 and 75%, respectively. These data indicate that PMN activity in the peripheral blood is increased with the presence of a flow-limiting coronary lesion showing an angiographic filling delay. Measuring PMN activity may be a useful approach to assess indications for and timing of angiography and/or adjunctive invasive therapies in patients with angina pectoris.

Value of Transthoracic Echocardiography for the Detection of High-Grade Coronary Artery Stenosis: Prospective Evaluation in 50 Consecutive Patients Scheduled for Coronary Angiography

We prospectively evaluated the feasibility of direct, transthoracic evaluation of coronary arteries to diagnose flow-limiting lesions. Second harmonic mode in B-mode and fundamental mode for Doppler examinations was used. A stenosis was diagnosed when maximal flow velocity at least doubled in comparison with that of the adjacent segment or when local velocity was at least 2 m/s. Of the left anterior descending coronary artery segments assessed, 34 were proximal, 35 middle, and 34 distal segments. The corresponding figures for circumflex coronary artery segments were 17 proximal and 11 middle segments and for the right coronary artery, 14 proximal and 15 distal segments. No distal circumflex and only 1 mid right coronary artery segment was visualized. Twenty-eight stenoses were diagnosed. Specificity for stenosis detection was 96% to 100% and sensitivity was 62% to 66%. Echo-cardiography was unable to document occlusions. Transthoracic echocardiography allows for coronary artery assessment in a significant portion of patients scheduled for coronary angiography. It may be used to document the presence of coronary artery stenosis. With further technologic improvements, transthoracic echocardiography could enable the monitoring of the restenosis process after percutaneous transluminal coronary angioplasty/stent intervention and coronary artery luminal narrowing after heart transplantation. (J Am Soc Echocardiogr 2000;13:1091-9.)

Exercise-Induced Symptomatic and Asymptomatic Myocardial Ischemia in Patients with Severe Coronary Artery Disease: Focus on the Efficacy and Safety of Gallopamil

Symptomatic and asymptomatic episodes of transient myocardial ischemia are well-known risk factors in patients with coronary artery disease. In a single-blind, randomized, and placebo-controlled study, the efficacy and safety of gallopamil was studied during a 1-week treatment period in 25 patients with high-grade coronary artery stenosis and frequent, exercise-induced episodes of myocardial ischemia. Eighteen patients were men, and seven patients were women; the mean age +/- SD was 59 +/- 7 years. After a 1-week run-in period (days 1-7), all patients were treated with gallopamil 50 mg t.i.d. (days 8-14) and placebo t.i.d. (days 15-21) or vice versa. Twenty-four-hour Holter monitoring, exercise testing, and adverse effects were controlled at days 7, 14, and 21. During the run-in period, all patients suffered a mean of 5.9 +/- 2.9 episodes of transient myocardial ischemia, mean ischemic duration was 38 +/- 29 min/day. Gallopamil increased exercise tolerance from 7.9 to 9.8 min (+24%, p < 0.05) and resulted in reduction of the weekly usage of short-acting nitrates by 45% compared to placebo. During 24-h Holter monitoring, mean heart rate at the onset of ST-segment depression increased from 106 to 118 beats/min (p < 0.05). The frequency of daily ischemic episodes was reduced after gallopamil administration from 6.1 to 3.9 episodes/day (-37%, p < 0.05), the total ischemic burden decreased for symptomatic episodes by -54% (p < 0.05) and for asymptomatic episodes by 29% (p < 0.05). Gallopamil modified the circadian distribution of ischemic episodes by modifying the morning peak of transient myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Southwestern Internal Medicine Conference: Evolving Concepts in the Treatment of Acute Myocardial Infarction

Recent studies in patients with transmural acute myocardial infarction have demonstrated that intravenous thrombolytic therapy with streptokinase or tissue plasminogen activator improves left ventricular function and reduces mortality. To accomplish this, these agents must be infused early, ie, within 3 to 4 hours of the onset of chest pain; later administration of the agents exerts no significant beneficial effect. Tissue plasminogen activator appears to be the most effective and safest of the available thrombolytic agents: its intravenous administration is followed by coronary reperfusion in about 70% of patients, and its use is not associated with allergic reactions, a systemic fibrinolytic state, or a prolonged fibrinolytic effect. Once reperfusion has been established with an intravenous thrombolytic agent, intravenous heparin is given for several days, followed by oral aspirin to prevent reocclusion. Since many of these patients have a residual high-grade coronary artery stenosis in the infarct-related artery, mechanical alleviation of the residual stenosis with angioplasty or bypass surgery is an attractive therapy 2 to 4 days after reperfusion, and preliminary data indicate that elective coronary angioplasty 3 days after thrombolytic therapy is beneficial. However, further studies are needed to assess more definitively the use of such an aggressive therapeutic strategy.

Coronary artery thrombosis in patients with unstable angina.

This report describes the clinical course, coronary artery anatomy, and ventricular function of 16 patients in whom coronary artery thrombosis was detected at the time of cardiac catheterisation. All patients had an unstable clinical course in which accelerated angina occurred a mean of four weeks (range four days to 12 weeks) before catheterisation, and four patients had recent subendocardial myocardial infarction. In all patients severe coronary artery disease was documented at catheterisation. Fifteen patients had segmental wall motion abnormalities involving the left ventricular wall that was supplied by the coronary artery in which there was thrombus. Three patterns of coronary artery thrombus were noted: (1) Thrombus proximal to high-grade coronary artery stenosis; (2) thrombus distal to high-grade coronary artery stenosis; and (3) thrombus in segments of the arterial tree in which there was no high-grade coronary artery stenosis. Though the precise cause of the coronary artery thrombosis in our patients is unknown, it may have been a result of stasis, a ruptured atherosclerotic plaque, or coronary spasm. The common clinical course with unstable angina of acute onset suggests the possibility that the thrombus may have been responsible for the abrupt change in clinical condition or may have been a contributing factor in the patients' course.

Coronary flow measurements with cine densitometry. II. Quantitative determinations of flow velocities and flow volumes through severe coronary stenoses during rest (author's transl)

The normal flow values through healthy or moderately narrowed coronary arteries, which had been determined by a new method of cine radiography, together with a computer, were published in this Journal in 1976. In the present paper we report the results of further studies of flow velocity and flow volume through high-grade coronary artery stenosis of severity III and III--IV. Compared with the results obtained on normal and mildly stenosed arteries, measurements at rest through severely stenosed coronaries showed an almost constant flow. The first results on aorto-coronary vein graft measurement are described.