Right Coronary Territory Research Articles

Predictive Accuracy of Dobutamine Stress Echocardiography in Detection of Presence and Extent of Coronary Artery Disease

Introduction: Exercise tolerance test (ETT) is an established screening test for coronary artery disease (CAD), but not feasible in 30−40% of patients. Dobutamine stress echocardiography (DSE) is an excellent alternative. Traditionally, inducible worsening of wall motion by 1 grade from baseline provides an index of CAD; worsening by 2 grade or more theoretically represents a more severe perfusion abnormality. The present study represents the inaugural experience of DSE at the National Institute of Cardiovascular Disease, Dhaka.
 Objective: To assess the predictive accuracy of DSE results with the presence and extent of CAD in subjects with suspected stable angina pectoris.
 Materials and Methods: In this prospective observational study, 35 subjects with intermediate to high probability of CAD were subjected to DSE followed by coronary angiography (CAG) within one month. Comparison of DSE results and predicted coronary artery involvement with angiographic findings were done. Overall sensitivity, specificity, accuracy as well as accuracy by arterial territory involvement were calculated.
 Results: DSE identified 82 abnormal segments, 66 with 1 grade change in 23 subjects (Group A) and 16 with 2 grade change in 8 subjects (Group B). CAG detected 54 significant lesions, 23 (42.59%) in left circumflex (LCX), 18 (33.33%) in left anterior descending (LAD), 11 (20.37%) in right coronary (RCA) and 2 (3.7%) in left coronary (LCA) artery. DSE had a sensitivity of 93.1% and a specificity of 66.7%. The accuracy was 88.57% overall, 94.29% for LAD and 91.43% for both LCX and RCA territories. Group B subjects had significantly higher number of coronary stenosis per patient (2.63 versus 1.38, p<0.001), triple vessel (62.5% versus 8.6%, p=0.003) and lower single vessel CAD (0% versus 47.8%, p=0.005).
 Conclusion: This study shows that DSE is a reliable test for prediction of the presence and extent of CAD.
 J Enam Med Col 2019; 9(1): 16-24

Parametric quantification of myocardial ischaemia using real‐time perfusion adenosine stress echocardiography images, with SPECT as reference method

Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique, provides images for off-line parametric perfusion quantification using Qontrast software. From replenishment curves, this generates parametric images of peak signal intensity (A), myocardial blood flow velocity (beta) and myocardial blood flow (Axbeta) at rest and stress. This may be a tool for objective myocardial ischaemia evaluation. We assessed myocardial ischaemia by RTP-ASE Qontrast((R))-generated images, using 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) as reference. Sixty-seven patients admitted to SPECT underwent RTP-ASE (SONOS 5500) during Sonovue infusion, before and throughout adenosine stress, also used for SPECT. Quantitative off-line analyses of myocardial perfusion by RTP-ASE Qontrast-generated A, beta and Axbeta images, at different time points during rest and stress, were blindly compared to SPECT. We analysed 201 coronary territories [corresponding to the left anterior descendent (LAD), left circumflex (LCx) and right coronary (RCA) arteries] from 67 patients. SPECT showed ischaemia in 18 patients. Receiver operator characteristics and kappa values showed that A, beta and Axbeta image interpretation significantly identified ischaemia in all territories (area under the curve 0.66-0.80, P = 0.001-0.05). Combined A, beta and Axbeta image interpretation gave the best results and the closest agreement was seen in the LAD territory: 89% accuracy; kappa 0.63; P<0.001. Myocardial isachemia can be evaluated in the LAD territory using RTP-ASE Qontrast-generated images, especially by combined A, beta and Axbeta image interpretation. However, the technique needs improvements regarding the LCx and RCA territories.

Parametric quantification of myocardial ischaemia using real-time perfusion adenosine stress echocardiography images, with SPECT as reference method

Background: Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique, provides images for off-line parametric perfusion quantification using Qontrast® software. From replenishment curves, this generates parametric images of peak signal intensity (A), myocardial blood flow velocity (β) and myocardial blood flow (Axβ) at rest and stress. This may be a tool for objective myocardial ischaemia evaluation. We assessed myocardial ischaemia by RTP-ASE Qontrast®-generated images, using 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) as reference. Methods: Sixty-seven patients admitted to SPECT underwent RTP-ASE (SONOS 5500) during Sonovue® infusion, before and throughout adenosine stress, also used for SPECT. Quantitative off-line analyses of myocardial perfusion by RTP-ASE Qontrast®-generated A, β and Axβ images, at different time points during rest and stress, were blindly compared to SPECT. Results: We analysed 201 coronary territories [corresponding to the left anterior descendent (LAD), left circumflex (LCx) and right coronary (RCA) arteries] from 67 patients. SPECT showed ischaemia in 18 patients. Receiver operator characteristics and kappa values showed that A, β and Axβ image interpretation significantly identified ischaemia in all territories (area under the curve 0·66–0·80, P = 0·001–0·05). Combined A, β and Axβ image interpretation gave the best results and the closest agreement was seen in the LAD territory: 89% accuracy; kappa 0·63; P<0·001. Conclusion: Myocardial isachemia can be evaluated in the LAD territory using RTP-ASE Qontrast®-generated images, especially by combined A, β and Axβ image interpretation. However, the technique needs improvements regarding the LCx and RCA territories.

Effect of Ischemia on Implantable Defibrillator Intracardiac Shock Electrograms

Few attempts have been made to extract information from the ventricular electrogram (EGM) recorded by implantable cardioverter defibrillators (ICD) aside from the discrimination of supraventricular tachycardia and ventricular tachycardia. The current study aims to examine the effect of ischemia in the major coronary artery distributions on the shock EGM from ICDs. Domestic crossbred pigs (n = 10, 20-40 kg) were implanted with a dual-coil right ventricular defibrillation system. Through the femoral approach, percutaneous balloon occlusion of the major coronary arteries was performed. The left anterior descending (LAD), left circumflex (LCx), and right coronary (RCA) arteries were occluded in random order for 3-5 minutes with 30-minute periods of reperfusion in between and the shock EGMs were recorded and analyzed. During peak ischemia, R wave amplitude increased by a mean of 204.3% (P = 0.003), increased by a mean of 73.8% (P = 0.0009), and decreased by a mean of 28.0% (P = 0.109) in the LAD, LCx, and RCA territories, respectively. During peak ischemia ST segments elevated by a mean of 105.3% (P = 0.041), elevated by a mean of 114.9% (P = 0.064), and decreased by a mean of 584.5% (P = 0.006) in the LAD, LCx, and RCA territories, respectively. Ischemia affects ICD shock EGMs in a manner that appears to vary depending on the culprit vessel. Our data demonstrate the feasibility of ischemia detection from ICD shock EGMs.

Hypertension and Smoking Are Associated With Reduced Regional Left Ventricular Function in Asymptomatic Individuals: The Multi-Ethnic Study of Atherosclerosis

This study sought to test the hypothesis that reduced regional left ventricular (LV) function is associated with traditional risk factors including hypertension, hypercholesterolemia, and smoking in asymptomatic individuals. Coronary artery disease is the main etiology of congestive heart failure in the U.S. and Europe. However, the relationship between risk factors for coronary artery disease and decreased myocardial function has not been studied systematically in asymptomatic individuals. The Multi-Ethnic Study of Atherosclerosis (MESA) is a cohort study designed to investigate the nature of atherosclerosis in asymptomatic individuals. A total of 1,184 participants (45 to 84 years old) underwent tagged cardiac magnetic resonance imaging. Regional LV function was quantified by analyzing peak systolic circumferential strain (Ecc) in regions corresponding to the left anterior descending (LAD), circumflex (LCX), and right coronary (RCA) territories. The association between risk factors and strains was studied using multiple linear regression. Higher diastolic blood pressure (DBP) was associated with lower Ecc (p < or = 0.002). The Ecc's in the LAD territory of participants with DBP <80, 80 to 84, 85 to 89, and > or =90 mm Hg were -15.6%, -14.8%, -14.2%, and -13.7%, respectively (p < 0.001). Similar results were documented in other territories and after multivariable analysis. Smokers had lower Ecc in the LAD and RCA regions compared with nonsmokers. Furthermore, dose response relationship between cigarette consumption measured in pack-years and regional LV dysfunction by Ecc was noted (p < or = 0.01 in LAD and RCA territories). Finally, combined diastolic hypertension and smoking was associated with a greater reduction of regional LV function. Higher diastolic blood pressure and smoking are associated with decreased regional LV function in asymptomatic individuals.