Quantitative coronary angiography in the estimation of the functional significance of coronary stenosis: correlations with dobutamine-atropine stress test

Deep learning-based prediction of future myocardial infarction using invasive coronary angiography: a feasibility study

BACKGROUND

Angiographic parameters can facilitate the risk stratification of coronary lesions but remain insufficient in the prediction of future myocardial infarction (MI).

AIMS

We compared the ability of humans, angiographic parameters and deep learning (DL) to predict the lesion that would be responsible for a future MI in a population of patients with non-significant CAD at baseline.

METHODS

We retrospectively included patients who underwent invasive coronary angiography (ICA) for MI, in whom a previous angiogram had been performed within 5 years. The ability of human visual assessment, diameter stenosis, area stenosis, quantitative flow ratio (QFR) and DL to predict the future culprit lesion (FCL) was compared.

RESULTS

In total, 746 cropped ICA images of FCL and non-culprit lesions (NCL) were analysed. Predictive models for each modality were developed in a training set before validation in a test set. DL exhibited the best predictive performance with an area under the curve of 0.81, compared with diameter stenosis (0.62, p=0.04), area stenosis (0.58, p=0.05) and QFR (0.67, p=0.13). DL exhibited a significant net reclassification improvement (NRI) compared with area stenosis (0.75, p=0.03) and QFR (0.95, p=0.01), and a positive nonsignificant NRI when compared with diameter stenosis. Among all models, DL demonstrated the highest accuracy (0.78) followed by QFR (0.70) and area stenosis (0.68). Predictions based on human visual assessment and diameter stenosis had the lowest accuracy (0.58).

CONCLUSION

In this feasibility study, DL outperformed human visual assessment and established angiographic parameters in the prediction of FCLs. Larger studies are now required to confirm this finding.

Standardizing the Definition and Analysis Methodology for Complete Coronary Artery Revascularization

Guideline‐based medical therapy is the foundation of treatment for individuals with coronary artery disease. However, revascularization with either percutaneous coronary intervention or coronary artery bypass grafting may be beneficial in patients with acute coronary syndromes, refractory symptoms, or in other specific scenarios (eg, left main disease and heart failure). While the goal of percutaneous coronary intervention and coronary artery bypass grafting is to achieve complete revascularization, anatomical and ischemic definitions of complete revascularization and their methodology for assessment remain highly variable. Such lack of consensus invariably contributes to the absence of standardized approaches for invasive treatment of coronary artery disease. Herein, we propose a novel, comprehensive, yet pragmatic algorithm with both anatomical and ischemic parameters that aims to provide a systematic method to assess complete revascularization after percutaneous coronary intervention or coronary artery bypass grafting in both clinical practice and clinical trials.

Outcome of Liver Transplant Recipients With Revascularized Coronary Artery Disease: A Comparative Analysis With and Without Cardiovascular Risk Factors

BACKGROUND

Coronary artery disease (CAD) is a significant problem during evaluation for liver transplantation (LT). We aim to assess survival in LT recipients based on presence, severity, extent of CAD, and cardiac events within 90 days of LT.

METHODS

Eighty-seven LT recipients with history of pre-LT angiogram (December 2005 to December 2012) were compared with 2 control groups without prior angiogram, 72 LT recipients matched for cardiovascular risk factors (control group I), and 119 consecutive LT recipients without any CV risk factors (control group II). CAD was assessed by (1) vessel score (≥50% reduction in luminal diameter), and (2) Extent score (Reardon scoring system).

RESULTS

Of the 87 LT recipients (study group), 58 (66.7%) had none or less than 50% stenosis, 29 (33.3%) had obstructive CAD (≥50% stenosis), 7 (8%) with single-vessel disease, and 22 (25.3%) with multivessel disease. In the study group, irrespective of prerevascularization severity of CAD (P = 0.357), number of segments involved (0, 1-2, > 2 segments, P = 0.304) and extent of CAD based on Reardon score (0, 1-9, >10, P = 0.224), comparable posttransplant survival was noted. Overall, patient survival in the revascularized CAD group was comparable to angiogram group without obstructive CAD, and both control group I and control group II (P = 0.184, Log Rank). Postoperative cardiac events within 90 days of LT predicted poor survival in study group as well as control groups.

CONCLUSIONS

Severity or extent of CAD does not impact post-LT survival, if appropriately revascularized. Early postoperative cardiac events are associated with inferior survival in LT recipients, irrespective of underlying CAD.

Glucagon-like peptide-1 derived cardioprotection does not utilize a KATP-channel dependent pathway: mechanistic insights from human supply and demand ischemia studies

BACKGROUND

Glucagon-like peptide-1 (7-36) amide (GLP-1) protects against stunning and cumulative left ventricular dysfunction in humans. The mechanism remains uncertain but GLP-1 may act by opening mitochondrial K-ATP channels in a similar fashion to ischemic conditioning. We investigated whether blockade of K-ATP channels with glibenclamide abrogated the protective effect of GLP-1 in humans.

METHODS

Thirty-two non-diabetic patients awaiting stenting of the left anterior descending artery (LAD) were allocated into 4 groups (control, glibenclamide, GLP-1, and GLP-1 + glibenclamide). Glibenclamide was given orally prior to the procedure. A left ventricular conductance catheter recorded pressure-volume loops during a 1-min low-pressure balloon occlusion (BO1) of the LAD. GLP-1 or saline was then infused for 30-min followed by a further 1-min balloon occlusion (BO2). In a non-invasive study, 10 non-diabetic patients were randomized to receive two dobutamine stress echocardiograms (DSE) during GLP-1 infusion with or without oral glibenclamide pretreatment.

RESULTS

GLP-1 prevented stunning even with glibenclamide pretreatment; the Δ % dP/dtmax 30-min post-BO1 normalized to baseline after GLP-1: 0.3 ± 6.8 % (p = 0.02) and GLP-1 + glibenclamide: -0.8 ± 9.0 % (p = 0.04) compared to control: -11.5 ± 10.0 %. GLP-1 also reduced cumulative stunning after BO2: -12.8 ± 10.5 % (p = 0.02) as did GLP-1 + glibenclamide: -14.9 ± 9.2 % (p = 0.02) compared to control: -25.7 ± 9.6 %. Glibenclamide alone was no different to control. Glibenclamide pretreatment did not affect global or regional systolic function after GLP-1 at peak DSE stress (EF 74.6 ± 6.4 vs. 74.0 ± 8.0, p = 0.76) or recovery (EF 61.9 ± 5.7 vs. 61.4 ± 5.6, p = 0.74).

CONCLUSIONS

Glibenclamide pretreatment does not abrogate the protective effect of GLP-1 in human models of non-lethal myocardial ischemia. Trial registration Clinicaltrials.gov Unique Identifier: NCT02128022.

Type D Personality and Coronary Plaque Vulnerability in Patients With Coronary Artery Disease: An Optical Coherence Tomography Study

OBJECTIVE

To investigate the association between Type D personality and higher incidence of major adverse cardiac events, we used in vivo optical coherence tomography (OCT) to evaluate the association between Type D with coronary plaque characteristics.

METHODS

A total of 109 patients who had culprit coronary plaque (s) were included in the study. The Type D construct was analyzed using both the categorized and the continuous approaches. Plaque vulnerability of culprit lesions was measured by OCT.

RESULTS

After adjusting for demographic and clinical factors, multivariate analysis demonstrated that Type D was associated with lipid plaque (odds ratio [OR] = 4.87, 95% confidence interval [CI] = 1.41-11.14, p = .025), thin cap fibroatheroma (OR = 3.84, 95% CI = 1.36-10.85, p = .011), and fibrous cap thickness (β = -1.43, standard error = 0.04, p = .001) analyzed by categorical approach. When analyzing Type D as continuous variable, the negative affectivity component was significantly related to plaque vulnerability, including lipid plaque (OR = 3.43, 95% CI = 1.23-9.52, p = .018), thin cap fibroatheroma (OR = 2.20, 95% CI = 1.10-4.40, p = .026), and fibrous cap thickness (β = -0.05, standard error = 0.02, p = .030), whereas no associations between the negative affectivity by social inhibition interaction term with OCT indices were found.

CONCLUSIONS

The results suggest that plaque characteristics in Type D have more features of plaque vulnerability. The negative affectivity component seems to drive the associations between Type D and vulnerable plaques. These findings provide new insights into the mechanism involved in the association between Type D and major adverse cardiac event.

Acute Beta Blockade at Peak Stress: Will It Alter the Sensitivity of Dobutamine Stress Echocardiography in Patients with Normal Resting Wall Motion?

BACKGROUND

We compared the accuracy of recovery phase images following administration of intravenous propranolol with peak stress images, for detection of coronary artery disease in patients with no resting wall motion abnormalities undergoing dobutamine stress echocardiography.

METHODS

We enrolled 100 consecutive patients with no resting wall motion abnormalities who underwent dobutamine stress echocardiography. Propranolol was injected after termination of dobutamine infusion. Positive peak stress images were defined as the induction of wall motion abnormalities at any stage before propranolol injection. Positive recovery phase images were defined as maintenance or worsening of wall motion abnormalities induced at peak stress, or the appearance of new wall motion abnormalities during recovery phase. Significant coronary stenosis was defined as ≥ 50% obstruction of ≥ 1 sizable artery by coronary angiography.

RESULTS

Seventy-two patients (72%) had significant coronary artery disease. Analysis of peak stress images revealed sensitivity, specificity, positive and negative predictive values of 80.6%, 85.7%, 93.5%, and 63.2%; the overall accuracy was 82%. Analysis of the recovery phase images revealed sensitivity, specificity, positive and negative predictive values of 91.7%, 75%, 90.4%, and 77.8%; here, the overall accuracy was 87%.

CONCLUSIONS

In patients with no resting wall motion abnormalities, acute beta blockade during dobutamine stress echocardiography improved the sensitivity of recovery phase images for detection of significant coronary artery disease versus peak stress images, but with reduced specificity.

KEY WORDS

Accuracy; Beta blocker; Coronary artery disease; Dobutamine stress echocardiography; Recovery phase images.

Atropine first is safer than conventional atropine administration in older people undergoing dobutamine stress echocardiography

OBJECTIVE

Early injection of atropine during dobutamine stress echocardiography (DSE) has been demonstrated in retrospective analyses to reduce the duration and dose of dobutamine infusion, while preserving a similar diagnostic accuracy with a lower incidence of adverse effects. This study explores the safety of using atropine as a start drug before dobutamine infusion (ADSE protocol) in comparison with the conventional protocol (DASE protocol) in older patients undergoing DSE for ischemia evaluation.

METHODS

One hundred consecutive older patients were prospectively enrolled. When eligible, they were randomly assigned to undergo either the DASE protocol (group A, 50 patients) or the ADSE protocol (group B, 50 patients) when atropine (1.0 mg) was first administered 3 min before dobutamine infusion followed by 0.5 mg increments (maximum 1.0 mg) thereafter. Patients were monitored for adverse drug effects. Test duration was calculated.

RESULTS

The mean age of the whole study cohort was 67.8±4.3 years and 58 (58%) were men. Patients in group A had longer test duration (21.8±1.3 versus 13.7±0.77 min, p<0.001) and higher mean dobutamine infusion rate (39±8.2 versus 28.2±9.5 μg/kg/min, p<0.001). The two groups received a similar total dose of atropine. Group A patients showed significantly higher incidence of extrasystoles, nonsustained ventricular tachycardia and severe hypotension (p<0.05).

CONCLUSION

In older patients undergoing DSE, using atropine as a start drug, that is, adopting the ADSE protocol, is associated with shorter test duration, lower mean dobutamine infusion rate and consequently fewer adverse effects.

Flow restoration post revascularization predicted by stenosis indexes: sensitivity to hemodynamic variability

The expected blood flow improvement following a coronary intervention is inversely related to the stenotic-to-normal flow ratio Qs/Qn. Since Qn cannot be measured prior to intervention, treatment decisions rely on stenosis-severity indexes, e.g., area stenosis (%AS), hyperemic stenosis resistance (HSR), and fractional flow reserve (FFR), where treatment cut-off levels have been established for each index based on presence of inducible ischemia. Here, we studied the dependence of these indexes-predicted Qs/Qn under physiological perturbations of stenosis features and of hemodynamic and mechanical conditions. Dynamic coronary flow was simulated based on measured coronary morphometric data and a physics-based computational model. Simulations were used to evaluate the relationship between each index level and Qs/Qn. Under each perturbation, an independence measure (IM) was calculated for each index based on the relative change in Qs/Qn associated with each perturbation. The results show that while %AS prediction of Qs/Qn is largely independent (IM > 90%) of physiological changes in heart rate, venous pressure, and lesion length and location on the epicardial tree, HSR is also independent of changes in left ventricle pressure. FFR-predicted Qs/Qn is also independent of changes in aortic pressure, blood hematocrit, and stenotic vessel stiffness. Nevertheless, independence of all indexes is substantially compromised (IM < 70%) under changes in vasculature stiffness. Specifically, a physiological stiffening elevates Qs/Qn value by 21% at the FFR cut-off value (0.75). These findings suggest that the current FFR cut-off value for treatment of stenotic lesions overestimates the benefit of coronary intervention in patients with a stiffer coronary vasculature (e.g., diabetics, hypertensives).

Liver transplantation outcome in patients with angiographically proven coronary artery disease: a multi-institutional study

Over the last decade the age of liver transplant (LT) recipients and the likelihood of coronary artery disease (CAD) in this population have increased. There are no multicenter studies that have examined the impact of CAD on LT outcomes. In this historical cohort study, we identified adult LT recipients who underwent angiography prior to transplantation at seven institutions over a 12-year period. For each patient we recorded demographic data, recipient and donor risk factors, duration of follow-up, the presence of angiographically proven obstructive CAD (≥50% stenosis) and post-LT survival. Obstructive CAD was present in 151 of 630 patients, the CAD(+) group. Nonobstructive CAD was found in 479 patients, the CAD(-) group. Patient survival was similar for the CAD(+) group (adjusted HR 1.13, CI = [0.79, 1.62], p = 0.493) compared to the CAD(-) group. The CAD(+) patients were further stratified into severe (CADsev, >70% stenosis, n = 96), and moderate CAD (CADmod, 50-70% stenosis, n = 55) groups. Survival for the CADsev (adjusted HR = 1.26, CI = [0.83, 1.91], p = 0.277) and CADmod (adjusted HR = 0.93, CI = [0.52, 1.66], p = 0.797) groups were similar to the CAD(-) group. We conclude that when current CAD treatment strategies are employed prior to transplant, post-LT survival is not significantly different between patients with and without obstructive CAD.

Imaging techniques in coronary atherosclerotic disease: dobutamine stress echocardiography--evidence and perspectives

Dobutamine stress echocardiography is the most widely disseminated noninvasive technique for the assessment of coronary artery disease. Its results are important for clinical decisions. It is a versatile technique with high sensitivity and specificity for detecting viable myocardium at jeopardy. More recently, strain rate imaging has been applied to stress echocardiography. This approach relies on tissue Doppler or two-dimensional strain imaging to quantify myocardial deformation. The application of contrast echocardiographic techniques to stress echocardiography enables left ventricular opacification for border enhancement and myocardial perfusion imaging. Thus, this application is not limited to stress echocardiography, but has utility whenever image quality adversely affects wall motion assessment. Recently, three-dimensional stress echocardiography imaging has been proposed as an alternative approach to assess myocardial ischemia.

Interaction of left ventricular geometry and myocardial ischemia in the response of myocardial deformation to stress

Myocardial deformation parameters are sensitive markers of global left ventricular (LV) systolic function, but their interaction with LV geometry is unknown. We sought to investigate the effect of LV geometry on myocardial deformation and its interaction with coronary artery disease (CAD). A total of 126 patients with normal resting LV function who underwent dobutamine stress echocardiography subsequently underwent coronary angiography within 6 months. Longitudinal myocardial deformation was calculated using tissue Doppler echocardiography. The extent of CAD was identified by quantitative coronary angiography. Patients with an increased relative wall thickness had a significantly lower peak strain rate (SR) and a smaller change in SR with stress, with no differences in the at rest values. Those with CAD, had significantly lower peak SR values and change in SR with no difference in resting measures. A linear regression model showed that the relative wall thickness and extent of CAD were the strongest predictors of change in SR. An increasing extent of CAD caused a steady degradation in the peak SR and change in peak SR. Markers of longitudinal myocardial deformation at peak stress reflect both myocardial and interstitial properties. In conclusion, a major determinant of subendocardial function is the wall thickness, as measured by the relative wall thickness, and not LV hypertrophy.

Methodological Analysis of Diagnostic Dobutamine Stress Echocardiography Studies

BACKGROUND

Dobutamine stress echocardiography (DSE) is an accepted test for the diagnosis of coronary artery disease (CAD), despite its wide diagnostic accuracy.

AIM

Which factors cause test variability of DSE for the diagnosis of CAD.

METHODS

In a retrospective analysis of 46 studies in 5,353 patients, the potential causes of diagnostic variability were systematically analyzed, including patient selection, definition of CAD, chest pain characteristics, confounding factors for DSE (left ventricular hypertrophy, left bundle branch block, female gender), work-up bias (present when patient's chance to undergo coronary angiography is influenced by the result of DSE), review bias (present when DSE is interpreted in relation to CAG), DSE protocol and definition of a positive DSE.

RESULTS

Diagnostic variability was related to definition of a positive test, but not related to the definition of CAD or DSE protocol. However, only three of eight methodological standards for research design found general compliance. Differences in the selection of the study population (quality of echocardiographic window, angina pectoris), handling of confounding factors and analysis of disease in individual coronary arteries were observed. Lack of data on analysis of relevant chest pain syndromes and handling of nondiagnostic test results hampered further evaluation of these standards.

CONCLUSION

Methodological problems may explain the wide range in diagnostic variability of DSE. An improvement of clinical relevance of DSE testing is possible by stronger adherence to common and new methodological standards.

Factors affecting sensitivity and specificity of diagnostic testing: dobutamine stress echocardiography

BACKGROUND

Clinical characteristics of patients, angiographic referral bias, and several technical factors may all affect the reported diagnostic accuracy of tests. The aim of this study was to assess their influence on the diagnostic accuracy of dobutamine stress echocardiography (DSE).

METHODS

The medical literature from 1991 to 2006 was searched for diagnostic studies using DSE and meta-analysis was applied to the 62 studies thus retrieved, including 6881 patients. These studies were analyzed for patient characteristics, angiographic referral bias, and several technical factors.

RESULTS

The sensitivity of DSE was significantly related to the inclusion of patients with prior myocardial infarctions (0.834 vs 0.740, P < .01) and defining the results of DSE as already positive in case of resting wall motion abnormalities rather than obligatory myocardial ischemia (0.786 vs 0.864, P < .01). Specificity tended to be lower when patients with resting wall motion abnormalities were included in a study (0.812 vs 0.877, P < .10). The presence of referral bias adversely affected the specificity of DSE (0.771 vs 0.842, P < .01).

CONCLUSION

This analysis suggests that the reported sensitivity of DSE is likely higher and the specificity lower than expected in routine clinical practice because of the inappropriate inclusion of patients with prior myocardial infarctions, the definition of positive results on DSE, and the negative influence of referral bias. However, in the patient subset that will be sent to coronary angiography, the opposite results can be expected.

Quantitative analysis of myocardial contrast enhancement by first-pass 64-multidetector computed tomography in patients with coronary heart disease

BACKGROUND

Although multidetector computed tomography (MDCT) allows non-invasive assessment of coronary artery stenosis, the presence of calcified lesions often lead to an overestimation of the stenosis. The present study was an evaluation of whether enhancement of first-pass myocardial data can improve the diagnostic accuracy of 64-MDCT.

METHODS AND RESULTS

Data from 70 patients with single-vessel disease who underwent 64-MDCT followed by catheter-based coronary angiography (CAG) were analyzed. Myocardial enhancement was quantified by exaimining the signal densities at diastole. Among a total of 83 plaque segments, 35 calcified plaque segments were detected and 46 segments were found to have more than 50% coronary stenosis on catheter-based CAG. The average diameter stenosis was 75.2+/-12.8%. Diagnosis by 64-MDCT of significant stenosis (segment-based analysis) had a sensitivity, specificity and accuracy for segments without calcified lesions of 92%, 100% and 99.7%, respectively, and 95.2%, 50%, and 77.1%, respectively, for calcified lesions. Taking into account the myocardial enhancement by calculating the decrease of the standardized signal densities in percent, these parameters could be improved to 95.2%, 85.7% and 91.4%, respectively, for segments with calcified lesions.

CONCLUSIONS

The diagnostic accuracy of 64-MDCT for stenosis with calcified lesions in particular can be improved by taking into account the myocardial enhancement data.

Comparison of quantitative coronary angiography and first-pass perfusion magnetic resonance imaging for the detection of an impaired coronary perfusion in nonsevere coronary stenosis

PURPOSE

To compare quantitative coronary angiography (QCA) and first-pass perfusion magnetic resonance imaging (FPP-MRI) in symptomatic patients with nonsevere coronary stenosis to detect a reduced coronary flow velocity reserve (CFVR).

MATERIALS AND METHODS

In 35 patients, FPP-MRI and CFVR measurements were performed in 40 coronary arteries with a diameter stenosis (DS) <70% by QCA. From FPP-MRI a myocardial perfusion reserve index (MPRI) was calculated. CFVR was calculated as the ratio of the average peak flow velocity during infusion of adenosine and at rest and was considered reduced if <2. Diagnostic performance of MPRI and DS to detect a reduced CFVR was compared by receiver operating characteristic (ROC) curve analysis.

RESULTS

CFVR was reduced in 16 coronary arteries (40%). Mean DS did not differ in coronary arteries with a reduced CFVR (41.0% +/- 13.3) and a normal CFVR (36.5% +/- 12.3; P = 0.281). Mean MPRI was lower in coronary arteries with a reduced CFVR (1.12 +/- 0.12) compared to a normal CFVR (1.33 +/- 0.2; P < 0.001). Sensitivity, specificity, and area under the ROC curve (AUC) were higher for MPRI (81%, 79%, 0.84) than for DS (56%, 58%, 0.60).

CONCLUSION

FPP-MRI detects impaired CFVR in symptomatic patients with nonsevere coronary stenosis more accurately than QCA and can identify patients with symptomatic ischemia.

Predictive value of dobutamine stress echocardiography for coronary artery disease detection in liver transplant candidates

Patients with obstructive coronary artery disease (CAD) undergoing orthotopic liver transplantation (OLT) are at increased risk of poor outcomes. The accuracy of dobutamine stress echocardiography (DSE) to detect obstructive CAD is not well established in this population. We retrospectively identified patients with end-stage liver disease who underwent both DSE and coronary angiography as part of risk stratification prior to OLT. One hundred and five patients had both DSE and angiography, of whom 14 had known CAD and 27 failed to reach target heart rate during DSE. Among the remaining 64 patients (45 men; average age 61 +/- 8 years) DSE had a low sensitivity (13%), high specificity (85%), low positive predictive value (PPV) (22%) and intermediate negative predictive value (NPV) (75%) for obstructive CAD. DSE as a screening test for obstructive CAD in OLT candidates has a poor sensitivity. The frequent chronotropic incompetence and low sensitivity in patients who achieve target heart rate, even in those with multiple cardiovascular disease risk factors, suggest that alternative or additional methods of risk stratification are necessary.

Comparison of coronary minimal lumen area quantification by sixty-four-slice computed tomography versus intravascular ultrasound for intermediate stenosis

The present study assessed 64-slice computed tomographic accuracy to quantify minimal lumen area (MLA) and determine lesion severity in intermediate stenosis by angiography compared with intravascular ultrasound (IVUS). Sixty-four-slice computed tomography (CT) has been shown to be effective in coronary stenotic assessment by visual estimation compared with angiography. However, angiography is not an accurate gold standard for intermediate stenotic quantification compared with IVUS. Forty patients (54 lesions) with 30% to 70% coronary stenosis by angiography in a major coronary branch were included. All patients underwent quantitative angiography, retrospective electrocardiographically gated 64-slice CT (Siemens), and IVUS (40-MHz Atlantis; Boston Scientific). MLA was manually traced by 2 blinded and independent operators on 64-slice computed tomographic cross-sectional reconstruction and compared with IVUS MLA. A lesion was considered significant if the MLA was <or=6 mm(2) for the left main coronary artery and <or=4 mm(2) for another epicardial vessel with CT and IVUS. The correlation between IVUS MLA and computed tomographic MLA was r = 0.88 (p <0.001). Interobserver variabilities (mean +/- SD) were 1.2 mm(2) for CT and 1.1 mm(2) for CT versus IVUS. Bland-Altman analysis showed a 95% confidence interval of -42% to +44% for computed tomographic measurement using IVUS as a reference. Sensitivity, specificity, accuracy, and Cohen's kappa coefficient for significant lesion classification using CT were 87%, 72%, 80%, and 0.6, respectively (p <0.0001). In conclusion, when using MLA, 64-slice CT was able to quantify coronary stenosis with good correlation compared with IVUS and determine lesion severity in patients with intermediate lesions by angiography.

16-MDCT Coronary Angiography Versus Invasive Coronary Angiography in Acute Chest Pain Syndrome: A Blinded Prospective Study

OBJECTIVE

The purpose of our study was to prospectively evaluate the usefulness of CT coronary angiography versus invasive coronary angiography for the detection of clinically significant coronary artery disease in patients hospitalized for acute chest pain syndrome.

SUBJECTS AND METHODS

Sixty-six consecutive patients (52 men and 14 women; average age, 57 +/- 11 [SD] years) who were hospitalized for acute chest pain syndrome underwent CT coronary angiography and invasive coronary angiography within an average time interval of 4 days. ECG-gated CT coronary angiography was performed with a 16-MDCT scanner (0.42-sec rotation time, 16 x 0.75 mm detector collimation). Beta-blockers were not administered routinely, and thus the average heart rate was 71 +/- 11 beats per minute. CT coronary angiographic images were evaluated concurrently by two radiologists, who were blinded to invasive coronary angiography results, for stenoses having a diameter of 50% or more, using a 15-segment classification, including all segments 2 mm or more in diameter. The consensus interpretation was compared with results of invasive coronary angiography.

RESULTS

CT coronary angiography was technically successful in 59 patients (89%). After exclusion of 20 (3.1%) of 649 coronary segments, which were classified as nonevaluable by CT coronary angiography, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT coronary angiography for identifying significant coronary artery disease in the remaining 629 coronary segments were 80% (68/85), 89% (482/544), 52% (68/130), 97% (482/499), and 87% (550/629), respectively. The overall accuracy for the main vessels (left main, left anterior descending, left circumflex, and right coronary arteries) was 93%, 88%, 86%, and 86%, respectively.

CONCLUSION

CT coronary angiography using a 16-MDCT scanner enables accurate noninvasive detection of significant coronary artery disease in patients hospitalized for acute chest pain syndrome. Furthermore, relative high sensitivity and specificity of CT coronary angiography can be achieved without pharmacologic manipulation of patient heart rates.

Comparison of lumens of intermediate coronary stenosis using 16-slice computed tomography versus intravascular ultrasound

We aimed to quantify ambiguous coronary stenosis using the minimal lumen area with 16-slice computed tomography compared with intravascular ultrasound. The sensitivity, specificity, and accuracy for significant lesion classification was 68%, 86%, and 78%, respectively. The correlation between intravascular ultrasound and CT minimal lumen area was r = 0.73 (p <0.001), and the 95% confidence interval for CT measurement was -72% to +56%.

Novel stress echocardiographic model incorporating the extent and severity of wall motion abnormality for risk stratification and prognosis

The prognostic value of stress echocardiography to predict future cardiac events using the extent and severity of wall motion abnormalities is not well defined. The objective of this study was to develop and validate a prognostic model for interpretation of stress echocardiographic studies by using the extent and severity of wall motion abnormalities. We evaluated 1,500 patients (59 +/- 13 years old; 51% men) who underwent stress echocardiography (34% on the treadmill exercise and 66% on dobutamine). Left ventricular regional wall motion was assessed by consensus of 2 experienced echocardiographers. Follow-up periods (mean 2.7 +/- 1.0 years) for confirmed myocardial infarction (n = 31) and cardiac death (n = 44) were identified. Multivariate regression analysis identified 2 independent predictors of cardiac events: the number of left ventricular wall segments with new wall motion abnormalities (an index of the extent of ischemia) and the maximal magnitude of new wall motion abnormalities (an index of the severity of ischemia). The ischemic extent (chi-square 48.7, p <0.0001) and maximal severity (chi-square 52.0, p <0.0001) were exponentially correlated with an increase in event rate. On the basis of these data, a prognostic model was defined that uses ischemic extent and maximal severity as stress-dependent orthogonal variables. With this 3-dimensional model, the predicted event rate ranged over sevenfold, from a low of 0.9%/year in patients without any wall motion abnormalities to a high of 6.7%/year in patients with extensive and severe wall motion abnormalities. The extent and severity of wall motion abnormalities by stress echocardiography are independent and cumulative predictors of prognosis in patients who have suspected or known ischemic heart disease.

Incremental Benefit of Myocardial Contrast to Combined Dipyridamole-Exercise Stress Echocardiography for the Assessment of Coronary Artery Disease

Background— Although assessment of myocardial perfusion by myocardial contrast echocardiography (MCE) is feasible, its incremental benefit to stress echocardiography is not well defined. We examined whether the addition of MCE to combined dipyridamole-exercise echocardiography (DExE) provides incremental benefit for evaluation of coronary artery disease (CAD).

Methods and Results— MCE was combined with DExE in 85 patients, 70 of whom were undergoing quantitative coronary angiography and 15 patients with a low probability of CAD. MCE was acquired by low-mechanical-index imaging in 3 apical views after acquisition of standard resting and poststress images. Wall motion, left ventricular opacification, and MCE components of the study were interpreted sequentially, blinded to other data. Significant (>50%) stenoses were present in 43 patients and involved 69 coronary territories. The addition of qualitative MCE improved sensitivity for the detection of CAD (91% versus 74%, P =0.02) and accurate recognition of disease extent (87% versus 65% of territories, P =0.003), with a nonsignificant reduction in specificity.

Conclusions— The addition of low-mechanical-index MCE to standard imaging during DExE improves detection of CAD and enables a more accurate determination of disease extent.

Magnetic resonance imaging versus Doppler guide wire in the assessment of coronary flow reserve in patients with coronary artery disease

BACKGROUND

Coronary flow velocity reserve (CFVR), defined as the ratio of maximal hyperaemic to baseline flow velocity, has been validated as a marker of physiological significance of a coronary lesion. Clinically, this parameter is measured invasively during X-ray angiography using the Doppler guide wire. With magnetic resonance (MR) imaging it is possible to quantify CFVR non-invasively.

DESIGN

The purpose of the study was to compare CFVR, acquired with MR imaging and the Doppler guide wire in patients with coronary artery disease.

METHODS

Twenty-two patients suffering from one- or two-vessel coronary artery disease as derived from diagnostic X-ray coronary angiography were included. Coronary flow velocity reserve was measured at baseline and during maximal hyperaemia, obtained by intravenous administration of adenosine using MR phase contrast velocity quantification. Within 2 weeks CFVR was measured invasively with a Doppler guide wire.

RESULTS

In 26 coronary arteries CFVR was acquired with both techniques. Mean CFVR in the stenosed and healthy reference arteries was 1.5 +/- 0.7 and 2.7 +/- 1.0 (P < 0.01) respectively for MR measurements and 1.9 +/- 0.7 and 3.1 +/- 0.6 (P < 0.01) respectively for Doppler measurements. Bland-Altman analysis revealed a non-significant mean difference between the two techniques of 0.4 +/- 1.2.

CONCLUSION

In a selected group of stable patients with coronary artery disease MR flow velocity quantification provides non-invasive data equivalent to the invasive Doppler guide wire data. Variability in both the MR and Doppler ultrasound measurement resulted in a significant scatter of data without systematic difference.

Comparison between visual assessment and quantitative angiography versus fractional flow reserve for native coronary narrowings of moderate severity

We tested the hypothesis that experienced interventional cardiologists can identify patients with fractional flow reserve (FFR) <0.75 either by visual assessment of the angiogram or by quantitative coronary angiography (QCA). Estimation of the significance of moderate lesions is difficult. FFR can determine the physiologic significance of a stenosis. Data comparing visual assessment and QCA of moderate lesions with FFR are limited. FFR was measured in 83 moderate lesions defined as having a 40% to 70% stenosis by visual inspection. An FFR <0.75 was considered "significant." Lesions were visually assessed by 3 experienced interventional cardiologists and their significance estimated. QCA was performed. Both analyses were compared with FFR. FFR averaged 0.82 +/- 0.11 and was <0.75 in 15 of 83 lesions (18%). The reviewers' classification was concordant with the FFR in about half the lesions. Concordance between reviewers was poor (Spearman's rho = 0.36). Visual assessment resulted in good sensitivity (80%) and negative predictive value (91%), but poor specificity (47%) and positive predictive value (25%) compared with FFR. By QCA, no patient with stenosis <60% or minimal luminal diameter >1.4 mm had FFR <0.75. QCA did not discriminate the significance of lesions outside of these parameters. Thus, neither visual assessment of an angiogram by experienced interventional cardiologists nor QCA can accurately predict the significance of most moderate narrowings.

Use of stress echocardiography to predict mortality in patients with diabetes and known or suspected coronary artery disease

OBJECTIVE

This study sought to determine whether stress echocardiography using exercise (when feasible) or dobutamine echo could be used to predict mortality in patients with diabetes.

RESEARCH DESIGN AND METHODS

Stress echo was performed in 937 patients with diabetes (aged 59 +/- 13 years, 529 men) for symptom evaluation (42%) and follow-up of known coronary artery disease (CAD) (58%). Stress echocardiography using exercise was performed in 333 patients able to exercise maximally, and dobutamine echo using a standard dobutamine stress was used in 604 patients. Patients were followed for < or = 9 years (mean 3.9 +/- 2.3) for all-cause mortality.

RESULTS

Normal studies were obtained in 567 (60%) patients; 29% had resting left ventricular (LV) dysfunction, and 25% had ischemia. Abnormalities were confined to one territory in 183 (20%) patients and to multiple territories in 187 (20%) patients. Death (in 275 [29%] patients) was predicted by referral for pharmacologic stress (hazard ratio [HR] 3.94, P < 0.0001), ischemia (1.77, P < 0.0001), age (1.02, P = 0.002), and heart failure (1.54, P = 0.01). The risk of death in patients with a normal scan was 4% per year, and this was associated with age and selection for pharmacologic stress testing. In stepwise models replicating the sequence of clinical evaluation, the predictive power of independent clinical predictors (age, selection for pharmacologic stress, previous infarction, and heart failure; model chi(2) = 104.8) was significantly enhanced by addition of stress echo data (model chi(2) = 122.9).

CONCLUSIONS

The results of stress echo are independent predictors of death in diabetic patients with known or suspected CAD. Ischemia adds risk that is incremental to clinical risks and LV dysfunction.

Adequate patient selection for coronary revascularization: an overview of current methods used in daily clinical practice

Widely used non-invasive stress modalities, like exercise ECG, MPS and stress-echocardiography, are the tests of first choice for the diagnosis of CAD. It has been shown in numerous studies that non-invasive assessment of perfusion abnormalities is an adequate strategy for risk stratification. Moreover, non-invasive stress testing should be performed before a diagnostic cardiac catheterization to document the presence of myocardial ischemia, as a prerequisite for coronary revascularization. Coronary angiography is the gold standard for identifying CAD; however this technique is limited in assessing functional severity of coronary narrowings ('illusion of luminology'; see also Figure 5). The recently introduced i.c. hemodynamic parameters (CFVR and FFR) can identify functional severity of specific lesions and have shown a good agreement with the results of non-invasive stress test in validation studies. Furthermore, there is accumulating evidence that it is safe to defer a PTCA procedure, based on normal FFR and CFVR values. As these indices are derived during an invasive cardiac catheterization procedure, its use is recommended during a so called 'ad hoc' PTCA setting. Furthermore, they are particularly useful for clinical decision making in patients with documented multivessel CAD, as both indices allow selective evaluation of coronary narrowings in different arteries. Revascularization procedures are costly and always have a potential risk. It is important to be aware that, using above mentioned methods, unnecessary interventions (lacking potential benefit) may be avoided.

Improved identification of viable myocardium using second harmonic imaging during dobutamine stress echocardiography

OBJECTIVE

To determine whether, compared with fundamental imaging, second harmonic imaging can improve the accuracy of dobutamine stress echocardiography for identifying viable myocardium, using nuclear imaging as a reference.

PATIENTS

30 patients with chronic left ventricular dysfunction (mean (SD) age, 60 (8) years; 22 men).

METHODS

Dobutamine stress echocardiography was carried out in all patients using both fundamental and second harmonic imaging. All patients underwent dual isotope simultaneous acquisition single photon emission computed tomography (DISA-SPECT) with (99m)technetium-tetrofosmin/(18)F-fluorodeoxyglucose on a separate day. Myocardial viability was considered present by dobutamine stress echocardiography when segments with severe dysfunction showed a biphasic sustained improvement or an ischaemic response. Viability criteria on DISA-SPECT were normal or mildly reduced perfusion and metabolism, or perfusion/metabolism mismatch.

RESULTS

Using fundamental imaging, 330 segments showed severe dysfunction at baseline; 144 (44%) were considered viable. The agreement between dobutamine stress echocardiography by fundamental imaging and DISA-SPECT was 78%, kappa = 0.56. Using second harmonic imaging, 288 segments showed severe dysfunction; 138 (48%) were viable. The agreement between dobutamine stress echocardiography and DISA-SPECT was significantly better when second harmonic imaging was used (89%, kappa = 0.77, p = 0.001 v fundamental imaging).

CONCLUSIONS

Second harmonic imaging applied during dobutamine stress echocardiography increases the agreement with DISA-SPECT for detecting myocardial viability.

Early dobutamine echocardiography for the assessment of coronary stenosis after first Q-wave myocardial infarction

We assessed the accuracy of early dobutamine stress echocardiography to detect infarct-related coronary artery and multivessel disease in patients with first Q wave myocardial infarction after withdrawal of cardioactive drugs. Dobutamine-atropine echocardiography was performed in 91 consecutive patients (mean age 59+/-6 years) 7+/-4 days after myocardial infarction. Dobutamine was infused at incremental doses of 5, 10, 20, 30 to 40 microg/kg/min each one dose for 3 min. Peak heart rate was 134+/-17 bpm. All patients underwent coronary angiography before discharge. Sensitivity, specificity and accuracy of ischemic and biphasic response to detect residual stenosis of infarct-related coronary artery were 70, 92 and 73%, respectively. The sensitivity, specificity and accuracy of ischemic or biphasic response were similar in the vascular territories of left anterior descending (74, 86 and 75%, respectively), right (67, 100 and 70%, respectively) and circumflex coronary arteries (64, 100, and 69%, respectively). Sensitivity, specificity and accuracy of heterozonal wall motion abnormalities for multivessel coronary artery disease were 64, 82 and 76%, respectively. Dobutamine stress echocardiography is sensitive and specific in detecting residual coronary stenosis and multivessel disease in patients with first Q-wave myocardial infarction. The test is safe even without pharmacological protection.

Second harmonic imaging improves sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease

OBJECTIVE

Our purpose was to assess the value of second harmonic imaging compared with fundamental imaging for the diagnosis of coronary artery disease during dobutamine stress echocardiography.

PATIENTS AND METHODS

Sixty-four patients underwent dobutamine stress echocardiography with both fundamental imaging and second harmonic imaging. Coronary angiography was performed within 3 months. Ischemia was defined as new or worsening wall motion abnormalities in > or = 1 segment during dobutamine stress echocardiography. Coronary artery disease was defined as a > or = 70% luminal diameter stenosis in > or = 1 coronary artery by coronary angiography.

RESULTS

There was a higher prevalence of segments with invisible border with fundamental compared with second harmonic imaging both at rest (11% vs 8%, P < .05) and at peak stress (17% vs 10%, P < .001). Significant coronary artery disease was present in 49 (77%) patients. The sensitivity of dobutamine stress echocardiography for detection of coronary artery disease by fundamental and second harmonic imaging was, respectively, 78% and 94% (P < .05), whereas specificity was similar (73% vs 73%). Second harmonic imaging had a particularly higher sensitivity for the diagnosis of 1-vessel disease (93% vs 50%, P < .05).

CONCLUSION

The use of second harmonic imaging improves the sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease compared with fundamental imaging, particularly for 1-vessel coronary artery disease, whereas specificity remains unchanged.

Impact of hypertension on the accuracy of exercise stress myocardial perfusion imaging for the diagnosis of coronary artery disease

AIM

To compare the accuracy of exercise stress myocardial perfusion single photon emission computed tomography (SPECT) imaging for the diagnosis of coronary artery disease in patients with and without hypertension.

METHODS

A symptom limited bicycle exercise stress test in conjunction with 99m technetium sestamibi or tetrofosmin SPECT imaging was performed in 332 patients (mean (SD) age, 57 (10) years; 257 men, 75 women) without previous myocardial infarction who underwent coronary angiography. Of these, 137 (41%) had hypertension. Rest SPECT images were acquired 24 hours after the stress test. An abnormal scan was defined as one with reversible or fixed perfusion defects.

RESULTS

In hypertensive patients, myocardial perfusion abnormalities were detected in 79 of 102 patients with significant coronary artery disease and in nine of 35 patients without. In normotensive patients, myocardial perfusion abnormalities were detected in 104 of 138 patients with significant coronary artery disease and in 16 of 57 patients without. There were no differences between normotensive and hypertensive patients in sensitivity (77% (95% confidence interval (CI) 69% to 86%) v 75% (95% CI 68% to 83%)), specificity (74% (95% CI 60% to 89%) v 72% (95% CI 60% to 84%)), and accuracy (77% (95% CI 70% to 84%) v 74% (95% CI 68% to 80%)) of exercise SPECT for diagnosing coronary artery disease. The accuracy of SPECT was greater than electrocardiography, both in hypertensive patients (p = 0.005) and in normotensive patients (p = 0.0001). For the detection of coronary artery disease in individual vessels, sensitivity was 58% (95% CI 51% to 65%) v 57% (95% CI 51% to 64%), specificity was 86% (95% CI 82% to 90%) v 85% (95% CI 81% to 89%), and accuracy was 74% (95% CI 70% to 78%) v 74% (95% CI 70% to 78%) in patients with and without hypertension (NS).

CONCLUSIONS

In the usual clinical setting, the value of exercise myocardial perfusion scintigraphy for diagnosing coronary artery disease is not degraded by the presence of hypertension.

Non-invasive prediction of angiographic progression of coronary artery disease by dipyridamole-stress echocardiography

BACKGROUND

Coronary angiography is the currently accepted standard means for assessing progression of coronary artery disease. A dipyridamole-echocardiography test (DET) might provide an alternative non-invasive functional imaging method for this purpose.

OBJECTIVE

To assess whether variations in results of serial DET match variations in angiographic assessments of coronary artery disease.

METHODS

From the Pisa Institute of Clinical Physiology stress-echocardiography data bank (1983-1998), we selected 60 patients satisfying the inclusion criteria of coronary angiography and DET having each been performed and interpreted twice independently and within 1 week. The second angiographic and stress-echocardiographic assessment was performed 45+/-31 months after the initial one. Angiographic progressors were defined a priori as patients with any progression of stenosis to occlusion and those with any stenosis > 30% with > 20% progression of stenosis measured by visual and quantitative coronary angiography. Stress-echocardiography progressors were defined as those patients who had previously had a negative test of a test having a positive result and those patients who had positive results of tests both in initial testing and in a second session of testing with the latter having a peak wall-motion-score index > 0.12 (on a scale of 1, normal to 4, dyskinetic in a 16-segment model) larger than the former.

RESULTS

Of the 60 patients, 44 were angiographic 'progressors' and 16 were 'non progressors'. Stress-echocardiographic responses were concordant with angiographic identification for 39 of 44 progressors and 15 of 16 non-progressors, with an overall concordance of 90%.

CONCLUSIONS

Measurement of dipyridamole-stress-echocardiographic response allows one to separate angiographic progressors and non-progressors efficiently, simply by taking into account the presence, extent and severity of stress-induced abnormalities of wall motion.

Intermediate coronary artery stenosis: evidence-based decisions in interventions to avoid the oculostenotic reflex

The prevalence of intermediate coronary artery stenosis (defined as a diameter stenosis of 40% to 70%) is quite large in patients undergoing PTCA. The coronary angiogram is considered the 'gold standard' for the definition of coronary anatomy, in spite of various limitations associated with its use. In recent years, sensor tipped guidewire based methods of physiologic assessment of stenosis severity, like myocardial fractional flow reserve, and poststenotic coronary flow reserve had established their role in the decision making in catheterization laboratory. The decision making should combine morphologic and physiologic assessment as better evidence based approach in guiding therapy to avoid the 'oculostenotic reflex'.

Value of transesophageal dobutamine stress echocardiography in assessing coronary artery disease

The introduction of digital echocardiography has significantly enhanced our ability to select the best set of frames for analysis. However, despite the beneficial attributes of transthoracic dobutamine stress echocardiography, poor quality 2-dimensional images continue to be a significant limiting factor in patients with chest deformities, severe chronic obstructive lung disease, marked obesity, and previous chest surgery. Transesophageal echocardiography provides a new window to monitor left ventricular contractility without the interference of bone and air-filled structures of the thoracic cage. The transesophageal dobutamine stress test is a logical but poorly explored modality to image/stress the heart in certain patients with known or suspected myocardial ischemia. Overall sensitivity (< or = 85%) and specificity (< or = 95-100%) of transesophageal dobutamine stress echocardiography appear to be similar to that of previous transthoracic studies, although no direct comparison has been accomplished between transthoracic and transesophageal stress images. False negative transesophageal dobutamine stress echocardiography results have been described in patients with single-vessel disease in whom ischemic regions may not have been visualized throughout the entire study. False positive study results may be present in patients with hypertension and myocardial hypertrophy that may have signs and symptoms of myocardial ischemia in absence of obstructive disease of the epicardial coronary arteries, presumably related to either microvascular disease or impaired vasodilatory reserve. The proportion of patients with coronary artery disease who need a transesophageal examination for reliable assessment of echocardiographic response to stress varies depending on the operators' skills, the interpreters' experience, and the use of videotape or digitizing systems for image analysis. Although clinically useful in its present transthoracic and transesophageal form, a major limitation of dobutamine stress echocardiographic study is the subjective visual interpretation of endocardial motion and wall thickening, which is only semiquantitative. Color kinesis and tissue Doppler imaging (TDI) are 2 novel echocardiographic techniques that color code endocardial motion and myocardial velocity online and have the potential to objectively quantify regional left ventricular function. Quantitative standardization of transthoracic and transesophageal data interpretation, such as establishing endocardial motion by color kinesis or velocity thresholds by TDI for an abnormal segmental response to stress, has the potential to decrease interobserver variability and increase interinstitutional agreement.

Does the lack of hyperkinesis during dobutamine stress echocardiography predict the functional significance of coronary arterial stenosis?

The clinical implication of the lack of hyperkinesis during dobutamine stress echocardiography (DSE) has not been determined. We hypothesized that a lack of hyperkinesis during graded doses of dobutamine infusion would reflect the severity of coronary flow abnormality distal to the stenosis and provide the functional significance of coronary arterial stenosis. The aim of the present study was to investigate the prevalence of the lack of hyperkinesis in patients with normal coronary arteries and to determine its value in patients with single-vessel disease. A total of 63 consecutive patients who subsequently revealed angiographically normal coronary arteries underwent DSE. Thirty-one consecutive patients with angina and single-vessel disease also underwent both DSE and exercise thallium single-photon emission computed tomography (SPECT). According to the response of wall motion during low and peak doses of dobutamine infusion, patients were divided into three groups (group A, hyperkinesis was present during both low dose and peak stress; group B, hyperkinesis was present only during low dose; group C, no hyperkinesis). SPECT images were divided into 16 segments, and thallium uptake at each segment was scored from 0 (normal) to 3 (severe defect). Thallium uptake score index (TSI) was calculated as total thallium score divided by 16 at stress and delayed image. The prevalence of group A, B and C was 56 (89%), 3 (5%), and 4 (6%) in patients with normal coronary arteries. The corresponding values were 11 (35%), 8 (26%), and 12 (39%) in patients with single-vessel disease (P < 0.0001). In patients with single-vessel disease, there was no significant difference in percent diameter stenosis (group A, 59% +/- 8%; group B, 69% +/- 16%; group C, 67% +/- 13%) and the prevalence of proximal stenosis (45%, 25%, and 42%) among three groups. However, TSI at stress image was significantly lower in group A (0.21 +/- 0.14) than in group B (0.45 +/- 0.20, P < 0.05) and group C (0.53 +/- 0.27, P < 0.01). TSI at delayed image was also significantly lower in group A (0.07 +/- 0. 11) than in group C (0.18 +/- 0.15, P < 0.05). Because the lack of hyperkinesis during DSE was observed in 11% of patients with normal coronary arteries, it does not always predict the presence of significant coronary artery stenosis. However, this finding related to the severity of perfusion abnormality by exercise thallium SPECT in patients with single-vessel disease. These results suggest that the lack of hyperkinesis during dobutamine infusion would predict functional significance of coronary arterial stenosis and provide myocardial perfusion status distal to the stenosis in patients with single-vessel disease.

Accuracy of dobutamine tetrofosmin myocardial perfusion imaging for the noninvasive diagnosis of transplant coronary artery stenosis

BACKGROUND

Exercise stress myocardial perfusion scintigraphy has been used for the diagnosis of transplant coronary artery stenosis (TCAS) in cardiac allograft recipients. However, the role of pharmacologic stress myocardial perfusion imaging has not been evaluated. Aim of the study is to assess the accuracy of dobutamine stress 99m technetium tetrofosmin myocardial perfusion imaging for the diagnosis of TCAS in heart transplant recipients.

PATIENTS AND METHODS

We studied 50 patients (age 56 +/- 8 year, 45 men) at a mean of 6.4 +/- 2.8 years after cardiac transplant with dobutamine (up to 40 ìg/kg/min) stress 99m technetium tetrofosmin SPECT. Resting images were acquired 24 hours after the stress study. Significant TCAS was defined as > or =50% luminal diameter stenosis by coronary angiography.

RESULTS

Significant TCAS was detected in 30 patients (60%). Myocardial perfusion abnormalities (reversible and/or fixed defects) were detected in 27 of the 30 patients with and in 9 of the 20 patients without significant TCAS (sensitivity = 90%, CI 82-98, specificity = 55% CI 41-69, positive predictive value = 75%, CI 63-87, negative predictive value = 79%, CI 67-90 and accuracy = 76%, CI 64-88). Patients with multivessel TCAS had a larger stress perfusion defect score (5.6 +/- 3.1 vs 3.2 +/- 2.4, p < 0.05) compared to patients with single vessel TCAS. Among patients with abnormal perfusion who had no significant TCAS, 2 had lesions <50%, 2 had luminal irregularities and 5 had no abnormalities at angiography. Therefore specificity was 62% (8/13) in patients without any detectable angiographic abnormalities.

CONCLUSIONS

Dobutamine stress tetrofosmin myocardial perfusion imaging is a highly sensitive method for the detection of TCAS in recipients of cardiac allografts. The high negative predictive value of the test indicates that patients who demonstrate normal perfusion by this method may be excluded from further invasive studies.

Can dobutamine stress echocardiography predict cardiac events in nonrevascularized diabetic patients following acute myocardial infarction?

STUDY OBJECTIVE

To determine whether the prognostic value of dobutamine stress echocardiography (DSE) performed early after acute myocardial infarction (AMI) is as high in diabetic patients as in nondiabetic patients.

DESIGN

Inception cohort study.

SETTING

Tertiary cardiac referral center.

PATIENTS AND INTERVENTIONS

Three hundred thirty-eight patients (116 diabetic and 222 nondiabetic) who underwent DSE after AMI were followed up for cardiac events.

MEASUREMENTS AND RESULTS

Outcome events were as follows: "hard" events consisted of cardiac death and nonfatal reinfarction, while "all events" included hard events and unstable angina. The mean follow-up duration was 21 +/- 9 months. DSE results were positive in 69 diabetic patients (59.5%) and 129 nondiabetic patients (58.1%; p = 0.817). During the follow-up period, there were 25 cardiac deaths, 16 cases of nonfatal reinfarction, and 55 cases of unstable angina. The Kaplan-Meier life table showed that a positive DSE result was associated with a lower event-free survival rate in nondiabetic but not in diabetic patients in terms of hard and all events. By multivariate analysis, a positive DSE result was the strongest independent predictor of future cardiac events in nondiabetic patients. However, in diabetics, a shorter dobutamine time, rather than a positive DSE result, independently predicted cardiac events.

CONCLUSIONS

Our preliminary data suggest that different DSE variables should be considered when assessing the likelihood of future events in diabetic and nondiabetic patients after AMI. The observation of shorter dobutamine time, instead of DSE positivity, has a higher prognostic value in diabetics. In diabetic patients, the only significant role of DSE positivity is for predicting future unstable angina; however, its predictive value is not as good as in nondiabetic patients.

Advances in Exercise Echocardiography Can This Technique Still Thrive in the Era of Pharmacologic Stress Testing?

In the current literature, pharmacologic stress techniques are the focus of interest and excitement regarding new technologies and new indications such as the diagnosis of viable myocardium. In contrast, exercise echocardiography has evolved less and is less amenable to the introduction of new technologies. This article reviews the indications for exercise echocardiography (especially in contrast to pharmacologic stress), its accuracy relative to other testing, and application to clinical decision making. Exercise echocardiography remains to be well accepted as a diagnostic and risk-assessment technique, and in some clinical situations it provides valuable data that are not available during pharmacologic stress testing.

Stress echocardiography in women

The diagnosis of coronary heart disease in women has been thought to be more difficult than in men, owing to the overall lower prevalence and severity of disease in women, as well as more subtle clinical presentations. Exercise electrocardiography is associated with a high rate of false-positive results. In contrast, exercise and pharmacologic stress echocardiography have been shown to have high sensitivity, specificity, and prognostic value in women, comparable to that obtained in a male population. Although exercise thallium provides high f disease accuracy, due to its cost, availability, and radiation exposure, it may not be the ideal initial test in women. Thus, compared with other modalities, the advantages of stress echocardiography include its lower cost, availability, and high diagnostic accuracy. In the evaluation of women with chest pain, the initial step should involve clinical stratification into low, moderate, or high-probability groups based on symptoms, age, and cardiovascular risk factors. In women with atypical chest pain and a low probability of coronary heart disease, further testing should be avoided because any positive result is likely to be falsely positive. In those women with a moderate likelihood of disease, the most efficient and cost-effective strategy includes stress echocardiography as the initial test. This approach avoids the high rate of false-positive results with subsequent unnecessary angiography generated by exercise electrocardiography, as well as minimalizing false-negative results, which would lead to delays and potential increase in morbidity and mortality from untreated coronary heart disease. The optimal strategy for women at high clinical risk may be either exercise echocardiography or cardiac catheterization as the initial test. Although the diagnosis of CAD in women is different than in men, it is not necessarily more difficult. Astute clinical evaluation, in conjunction with judicious use of diagnostic testing, yields excellent results.

Integrated evaluation of relation between coronary lesion features and stress echocardiography results: the importance of coronary lesion morphology

OBJECTIVES

The aim of this study was to analyze, in the same group of patients, the relationship between multiple variables of coronary lesion and results of exercise, dobutamine and dipyridamole stress echocardiography tests.

BACKGROUND

Integrated evaluation of the relation between stress echocardiography results and angiographic variables should include not only the assessment of stenosis severity but also evaluation of other quantitative and qualitative features of coronary stenosis.

METHODS

Study population consisted of 168 (138 male, 30 female, mean age 51+/-9 years) patients, on whom exercise (Bruce treadmill protocol), dobutamine (up to 40 mcg/kg/min) and dipyridamole (0.84 mg/kg over 10 min) stress echocardiography tests were performed. Stress echocardiography test was considered positive for myocardial ischemia when a new wall motion abnormality was observed. One-vessel coronary stenosis ranging from mild stenosis to complete obstruction of the vessel was present in 153 patients, and 15 patients had normal coronary arteries. The observed angiographic variables included particular coronary vessel, stenosis location, the presence of collaterals, plaque morphology according to Ambrose classification, percent diameter stenosis and obstruction diameter as assessed by quantitative coronary arteriography.

RESULTS

Covariates significantly associated with the results of physical and pharmacological stress tests included for all three stress modalities presence of collateral circulation, percent diameter stenosis and obstruction diameter, as well as lesion morphology (p < 0.05 for all, except collaterals for dobutamine stress test, p = 0.06). By stepwise multiple logistic regression analysis, the strongest predictor of the outcome of exercise echocardiography test was only percent diameter stenosis (p = 0.0002). However, both dobutamine and particularly dipyridamole stress echocardiography results were associated not only with stenosis severity - percent diameter stenosis (dobutamine, p = 0.04; dipyridamole, p = 0.003) - but also, and even more strongly, with lesion morphology (dobutamine, p = 0.006; dipyridamole, p = 0.0009). As all of stress echocardiography results were significantly associated with percent diameter stenosis, the best angiographic cutoff in relation to the results of stress echocardiography test was: exercise, 54%; dobutamine, 58% and dipyridamole, 60% (p < 0.05 vs. exercise).

CONCLUSIONS

Integrated evaluation of angiographic variables have shown that the results of dobutamine and dipyridamole stress echocardiography are not only influenced by stenosis severity but also, and even more importantly, by plaque morphology. The results of exercise stress echocardiography, although separately influenced by plaque morphology, are predominantly influenced by stenosis severity, due to a stronger exercise capacity in provoking myocardial ischemia in milder forms of coronary stenosis.

Dobutamine stress echocardiography in the prediction of acute or chronic myocardial infarction

BACKGROUND

We assessed the value of dobutamine stress echocardiography (DSE) in predicting cardiac events in patients with acute or chronic myocardial infarction (MI), and we studied the association between DSE and these events.

METHODS AND RESULTS

Two hundred sixty-six patients (mean [+/-SD] age 65.3 +/- 11.4 years) with acute (n = 139) or chronic (n = 127) MI were recruited from March 1995 through April 1997. Both groups underwent DSE and were followed up for an average of 14.1 +/- 8.0 months. DSE was positive in 111 (79.9%) patients with acute MI and 65 (51.2%) patients with chronic MI (P <.0001 ). Positive DSE results were associated with a higher rate of all cardiac events (cardiac mortality rate, reinfarction, and unstable angina) than negative DSE results in both patients with acute MI and patients with chronic MI (44 in 111 patients vs 6 in 28 patients, P =.052, and 31 in 65 patients vs 10 in 62 patients, P <.0001, respectively). Among patients with acute MI, the positive and negative predictive values of DSE for all cardiac events were 39.6% (95% confidence interval [CI] 30.5% to 48. 7%) and 78.6% (95% CI 63.4% to 93.8%), respectively. In chronic MI, the positive and negative predictive values were 47.7% (95% CI 35.5% to 59.8%) and 83.9% (95% CI 74.7% to 93.0%), respectively. In both acute (P =.03) and chronic (P <.0001 ) MI, positive DSE findings were independent predictors of all cardiac events.

CONCLUSIONS

DSE is useful for predicting cardiac events. A positive finding on DSE is an independent predictor of cardiac events after both acute and chronic MI, whereas a negative DSE result predicts a low likelihood of subsequent cardiac events.

Optimal criteria for the diagnosis of coronary artery disease by dobutamine stress echocardiography

The diagnosis of coronary artery disease (CAD) on the basis of inducible ischemia in > or = 2, rather than 1, segments was suggested to improve specificity of dobutamine stress echocardiography (DSE). However, the impact of using these criteria on the sensitivity and accuracy of DSE was not studied. We studied the accuracy of DSE (up to 40 microg/kg/min) for the diagnosis of CAD in 290 patients with suspected myocardial ischemia using the criteria of > or = 1 and > or = 2 ischemic segments. Ischemia was defined as new or worsening wall motion abnormalities using a 16-segment model. Among the 85 patients without previous myocardial infarction, significant CAD was detected in 51 (60%). Sensitivity, specificity, and accuracy of DSE using > or = 1 ischemic segment were 73%, 85%, and 78%, respectively. Those using > or = 2 segments were 67%, 94%, and 78%, respectively (p = NS). Regional specificity improved by using > or = 2 segments (91% vs 96%, p <0.05) at the expense of an equivalent reduction in regional sensitivity (60% vs 44%, p <0.05), whereas the regional accuracy was similar (80% vs 79% for > or = 1 and > or = 2 segments, respectively). In the 205 patients with previous myocardial infarction, the criterion of ischemia in > or = 1 segment had a higher sensitivity and accuracy for overall diagnosis of CAD (75% vs 64%, p <0.05; 77% vs 68%, p <0.05), infarct-related CAD (64% vs 47%, p <0.005; 70% vs 57%, p <0.01), and remote CAD (74% vs 57%, p <0.005; 78% vs 69%, p <0.05) than the criterion of > or = 2 segments, respectively. It is concluded that in patients without previous myocardial infarction, the use of > or = 2 ischemic segments by DSE for the diagnosis of CAD does not improve the accuracy of DSE compared with the criterion of > or = 1 ischemic segment. Conversely, in patients with previous infarction the use of > or = 2 segments reduces the overall and regional sensitivity and accuracy without a significant improvement in specificity.

Ultrasonic tissue characterization in predicting residual ischemia and myocardial viability for patients with acute myocardial infarction

The identification of viable myocardium and residual ischemia in patients with acute myocardial infarction has important prognostic implications. The ultrasonic tissue characterization with integrated backscatter and dobutamine-atropine stress echocardiography were performed 8.3+/-3 days after AMI in 30 patients. After coronary angioplasty for the residual stenosis of infarct-related artery, both modalities were repeated. The parameter obtained from ultrasonic tissue characterization, phase-weighted variation, could differentiate the myocardium with residual coronary stenosis or nonviable myocardium from the viable myocardium without residual coronary stenosis (p < 0.001). Using the cutoff value of 5.8 dB, the sensitivity, specificity and accuracy for detecting viable myocardium without residual coronary stenosis were 75%, 100% and 90.2%, respectively. The phase-weighted variation of the viable infarction zone restored after the coronary stenosis was relieved. In contrast, the nonviable myocardium had a small phase-weighted variation that was irrelevant to the patency of the infarct-related artery. The ultrasonic tissue characterization may be used in identifying patients with acute myocardial infarction whose infarction zones are viable without residual ischemia.