Danai Kitkungvan

Optimal Adenosine Stress for Maximum Stress Perfusion, Coronary Flow Reserve, and Pixel Distribution of Coronary Flow Capacity by Kolmogorov-Smirnov Analysis.

Background— Different adenosine stress imaging protocols have not been systemically validated for absolute myocardial perfusion and coronary flow reserve (CFR) by positron emission tomography, where submaximal stress precludes assessing physiological severity of coronary artery disease. Methods and Results— In 127 volunteers, serial rest–stress positron emission tomography scans using rubidium-82 with various adenosine infusion protocols identified (1) the protocol with maximum stress perfusion and CFR, (2) test–retest precision in same subject, (3) stress perfusion and CFR after adenosine compared with dipyridamole, (4) heterogeneity of coronary flow capacity combining stress perfusion and CFR, and (5) potential relevance for patients with risk factors or coronary artery disease. The adenosine 6-minute infusion with rubidium-82 injection at 3 minutes caused CFR that was significantly 15.7% higher than the 4-minute adenosine infusion with rubidium-82 injection at 2 minutes and significantly more homogeneous by Kolmogorov–Smirnov analysis for histograms of 1344 pixel range of perfusion in paired positron emission tomographies. In a coronary artery disease cohort separate from volunteers of this study, compared with the 3/6-minute protocol, the 2/4-minute adenosine protocol would potentially have changed 332 of 1732 (19%) positron emission tomographies at low-risk physiological severity CFR ≥2.3 to CFR <2.0, thereby implying high-risk quantitative severity potentially appropriate for interventions but because of suboptimal stress of the 2/4 protocol in some patients. Conclusions— The 6-minute adenosine infusion with rubidium-82 activation at 3 minutes produced CFR that averaged 15.7% higher than that in the 2/4-minute protocol, thereby potentially providing essential information for personalized management in some patients.

Clinical Utility of Enhanced Relative Activity Recovery on Systolic Myocardial Perfusion SPECT: Lessons from PET

SPECT and PET myocardial perfusion images show greater myocardial intensity and homogeneity in systole than diastole because of greater systolic myocardial thickness, less partial volume loss, and enhanced activity recovery. Consequently, conventional myocardial perfusion images obtained from whole cardiac cycles have lower myocardial intensity and greater heterogeneity than systolic images. Considering relative activity distribution on SPECT systolic images may add clinical utility to whole-cycle images and wall motion. Methods: Patients undergoing coronary angiogram within 4 mo after SPECT myocardial perfusion imaging were reviewed. Images were interpreted by 2 masked interpreters using a 17-segment, 5-point scale to determine summed rest scores (SSS), summed stress scores, and summed difference scores on conventional and systolic images in 603 patients (55.6% no coronary artery disease [no-CAD] and 44.4% CAD). Studies were considered normal when the SSS was less than 4 and summed difference score was less than 2. Results: In the no-CAD group, systolic SSS was lower than SSS from conventional images (2 ± 2.3 vs. 3 ± 2.6, P < 0.001). In contrast, SSS derived from systolic and conventional images were not different in the obstructive CAD group (9.1 ± 7.6 vs. 9.2 ± 7.4, P = 0.559). When systolic images were considered, true-negative studies increased from 27.2% to 43.3% (P < 0.001) whereas false-positive studies decreased from 28.4% to 12.3% (P < 0.001). True-positive (38% vs. 37.2%, P = 0.505) and false-negative studies (6.5% vs. 7%, P = 0.450) were not significantly changed. Diagnostic accuracy increased from 65.2% to 80.8% (P < 0.001). Conclusion: For gated SPECT myocardial perfusion imaging, when relative activity distribution on systolic images was considered, false-positive studies were reduced and diagnostic accuracy was improved.

Risk Prediction Model for Permanent Pacemaker Implantation after Transcatheter Aortic Valve Replacement

ABSTRACT Background: Atrioventricular conduction disturbance requiring permanent pacemaker (PPM) implantation is the most common complication after transcatheter aortic valve replacement (TAVR). Improved risk stratification for potential need for post-procedure PPM implant prior to the TAVR procedure is warranted. The aim of this study was to develop and validate a risk-prediction model for PPM implantation after TAVR. Methods: This PPM risk assessment model was developed using the 2012&2013 National Inpatient Sample (NIS). A logistic regression model was built to identify the predictors of PPM placement. The performance of the model was validated using the NIS 2014 dataset. Results: Of 18,400 patients in the development cohort, 1,825 (9.9%) patients required PPM implantation after TAVR. After multivariate analysis, final predictive covariates of PPM implantation included left or right bundle branch block, bradycardia, 2nd-degree AV block and transfemoral approach. The estimated regression coefficients associated with these predictors were used to develop a scoring system. The proposed scoring system showed good discrimination in both development and validation cohorts, with c-statistics of 0.754 (95% CI: 0.726–0.782) and 0.746 (95% CI: 0.721–0.772) respectively. Calibration analysis indicated a good agreement between the observed rate of PPM and predicted risks of PPM by the risk score. Conclusions: This PPM risk prediction model derived using the NIS database is a simple tool that can estimate individual risk of PPM prior to TAVR procedure. The model displayed good discrimination and calibration indices. This risk score can provide valuable information for patients’ counseling and also help identify high-risk patients who need close monitoring immediately after the TAVR procedure.

Echocardiographic measures associated with the presence of left ventricular thrombus in patients with chemotherapy-related cardiac dysfunction

Previous studies have not evaluated the prevalence and specific risk factors for the development of left ventricular (LV) thrombus in patients with severely reduced left ventricular dysfunction due to chemotherapy‐related cardiomyopathy. We sought to evaluate the prevalence and potential markers of LV thrombus in this patient population.

Museum Image: Multimodality Imaging of a Cardiac Pseudotumor.

A 77-year-old asymptomatic female who had recently undergone 2-vessel coronary artery bypass surgery was referred from another hospital for surgical removal of a left atrial mass that was found on a recent transthoracic echocardiogram (TTE). Cardiac magnetic resonance imaging was obtained for further anatomical evaluation and tissue characterization. Cine-steady state free precession imaging demonstrated a large, wellcircumscribed mass involving the posterolateral mitral annulus without surrounding tissue invasion or compromise to mitral valvular function. T1 turbo spin-echo and T2 turbo spin-echo with fat suppression images showed the mass to be hypointense to myocardium (A and B, arrows), indicating an absence of significant fat or fluid. Absence of resting first-pass perfusion with gadolinium contrast administration indicated a lack of vascularity (C, arrow). Delayed hyperenhancement imaging showed a characteristic pattern of peripheral rim hyperenhancement consistent with a fibrous cap and a dark avascular core (D, arrow). These findings are most consistent with caseous mitral annular calcification. This was then verified with noncontrast cardiac computed tomography that demonstrated a large, hyperdense, calcified mass (F, arrow). Once TTE images could be obtained, review of the outside images (apical 4-chamber) similarly demonstrated a large, round, echodense mass at the posterior mitral annulus (E, arrow). Mitral valve function was normal without evidence of either mitral regurgitation or mitral stenosis. The patient was reassured of its benign prognosis, and conservative management/observation was advised.

PREVALENCE AND RISK FACTORS OF LEFT VENTRICULAR THROMBUS IN NONISCHEMIC CARDIOMYOPATHY PATIENTS WITH SEVERE LEFT VENTRICULAR SYSTOLIC DYSFUNCTION

Previous studies have not evaluated the prevalence and the presence of specific risk factors for the development of left ventricular thrombus (LVT) among chemotherapy related cardiomyopathy (CRC) patients who develop severe left ventricular (LV) systolic dysfunction. We used echocardiographic and