Anthony Wassef

Radiation Dose Reduction in the Cardiac Catheterization Laboratory Utilizing a Novel Protocol

OBJECTIVES This study reports the results a novel radiation reduction protocol (RRP) system for coronary angiography and interventional procedures and the determinants of radiation dose. BACKGROUND The cardiac catheterization laboratory is an important source of radiation and should be kept in good working order with dose-reduction and monitoring capabilities. METHODS All diagnostic coronary angiograms and percutaneous coronary interventions from a single catheterization laboratory were analyzed 2 months before and after RRP implementation. The primary outcome was the relative dose reduction at the interventional reference point. Separate analyses were done for conventional 15 frames/s (FPS) and at reduced 7.5 FPS post-RRP groups. RESULTS A total of 605 patients underwent coronary angiography (309 before RRP and 296 after RRP), with 129 (42%) and 122 (41%) undergoing percutaneous coronary interventions before and after RRP, respectively. With RRP, a 48% dose reduction (1.07 ± 0.05 Gy vs. 0.56 ± 0.03 Gy, p < 0.0001) was obtained, 35% with 15 FPS RRP (0.70 ± 0.05 Gy, p < 0.0001) and 62% with 7.5 FPS RRP (0.41 ± 0.03 Gy, p < 0.001). Similar dose reductions for diagnostic angiograms and percutaneous coronary interventions were noted. There was no change in the number of stents placed or vessels intervened on. Increased dose was associated with male sex, radial approach, increasing body mass index, cine runs, and frame rates. Using a multivariable model, a 48% relative risk with RRP (p < 0.001), 44% with 15 FPS RRP and 68% with 7.5 FPS RRP was obtained. CONCLUSIONS We demonstrate a highly significant 48.5% adjusted radiation dose reduction using a novel algorithm, which needs strong consideration among interventional cardiology practice.

To Transmit or Not to Transmit: How Good Are Emergency Medical Personnel in Detecting STEMI in Patients With Chest Pain?

BACKGROUND There is growing use of prehospital electrocardiograms (ECGs) in establishing early diagnosis of ST segment myocardial infarction (STEMI) to facilitate early reperfusion. This study aimed to determine the predictive value of prehospital ECGs interpreted by nonphysician emergency medical services (EMS) in chest pain presentations. METHODS In our city of 658,700 people, EMS/paramedics received 21 hours of instruction on STEMI management, ECG acquisition, and interpretation. Suspected STEMI ECGs were wirelessly transmitted to and discussed with a physician for possible therapy. ECGs deemed negative for STEMI by EMS were not transmitted; patients were transported to the closest hospital without prehospital physician involvement. RESULTS From July 21, 2008 to July 21, 2010, there were 5426 chest pain calls to EMS, 380 were suspected STEMI cases. The remaining ECGs were deemed negative for STEMI by EMS. To audit the nontransmitted ECGs we analyzed 323 consecutive patients over 2 selected months (January and June 2010) for comparison. Of nontransmitted cases there was 1 missed and 2 STEMIs that developed subsequently. Based on 380 transmitted and 323 nontransmitted cases, the sensitivity and specificity of EMS detecting STEMI were 99.6% and 67.6%, respectively. The positive and negative predictive values for STEMI were 59.5% and 99.7%, respectively. CONCLUSIONS Our findings demonstrate nonphysician EMS interpretation of STEMI on prehospital ECG has excellent sensitivity and high negative predictive value. This finding supports the use of prehospital ECGs interpreted by EMS to help identify and facilitate treatment of STEMI. These results may have broad implications on staffing models for first responder/EMS units.

The Role of Three-Dimensional Echocardiography in the Assessment of Right Ventricular Dysfunction after a Half Marathon: Comparison with Cardiac Magnetic Resonance Imaging

BACKGROUND Although marathon running is associated with transient right ventricular (RV) systolic dysfunction as detected by two-dimensional transthoracic echocardiography, quantitative assessment of the right ventricle is difficult because of its complex geometry. Little is known about the use of real-time three-dimensional echocardiography (RT3DE) in the detection of cardiac dysfunction after a half marathon. The aim of this study was to assess the extent of RV dysfunction after the completion of a half marathon using cardiac biomarkers, RT3DE, and cardiac magnetic resonance imaging (CMR). METHODS A prospective study was performed in 15 individuals in 2009 participating in the Manitoba Half Marathon. Cardiac biomarkers (myoglobin, creatine kinase-MB and cardiac troponin T) were assessed and RT3DE and CMR were performed 1 week before, immediately after, and 1 week after the race. RESULTS At baseline, cardiac biomarkers and ventricular function were within normal limits. Immediately following the half marathon, all patients demonstrated elevated cardiac troponin T levels, with a median value of 0.37 ng/mL. RV ejection fraction, as assessed by RT3DE, decreased from 59 ± 4% at baseline to 45 ± 5% immediately following the race (P < .05). On CMR, RV end-diastolic volume increased after the half marathon, and the RV ejection fraction was reduced, at 47 ± 5% compared with 60 ± 2% at baseline (P < .05). There were strong linear correlations between RV ejection fraction assessed by RT3DE and CMR at baseline and after the half marathon (r = 0.69 and r = 0.87, P < .01, respectively). CONCLUSIONS Compared with CMR, RT3DE is a feasible and reproducible method of assessing transient RV dysfunction in athletes completing a half marathon.

Cardiac Outcomes Through Digital Evaluation (CODE) STEMI Project: Prehospital Digitally-Assisted Reperfusion Strategies

BACKGROUND Guidelines for reperfusion in ST-elevation myocardial infarction (STEMI) were recently adopted by the Canadian Cardiovascular Society. We have developed a blended model of prehospital thrombolytic (PHL) therapy or primary percutaneous coronary intervention (PPCI) activation, in order to achieve guideline times. METHODS In our urban centre of 658,700 people, emergency medical services (EMS) were trained to perform and screen electrocardiograms (ECGs) for suspected STEMI. Suspected ECGs were transmitted to a physicians hand-held device. If the physician confirmed the diagnosis they coordinated initiation of either PHL or PPCI. In cases where physicians found the prehospital ECG negative for STEMI (PHENST), patients were transported to the closest emergency room. RESULTS From July 21, 2008 to July 21, 2010, the Cardiac Outcomes Through Digital Evaluation (CODE) STEMI project received 380 transmitted calls. There were 226 confirmed STEMI by the on-call physician, 158 (70%) received PPCI, 48 (21%) received PHL, and 20 (9%) had angiography but no revascularization. The PPCI, median time from first medical contact to reperfusion was 76 minutes (interquartile range [IQR], 64-93). For PHL, median time from first medical contact to needle was 32 minutes (IQR, 29-39). The overall mortality rate for the STEMI patients was 8% (PHL = 4 [8.3%], PPCI = 8 [5%], medical therapy = 7 [35%]). There were 154 PHENST patients, 44% later diagnosed with acute coronary syndrome. The mortality rate for PHENST was 14%. CONCLUSIONS Through a model of EMS prehospital ECG interpretation, digital transmission, direct communication with a physician, and rapid coordinated service, we demonstrate that benchmark reperfusion times in STEMI can be achieved.

Functional Mitral Regurgitation: Current Understanding and Approach to Management

Functional mitral regurgitation (FMR) is a challenging clinical entity that frequently complicates ischemic and nonischemic cardiomyopathy. The underlying pathophysiology of FMR is caused primarily by ventricular and subvalvular apparatus dysfunction which causes failure of proper leaflet coaptation. Echocardiography is the primary modality used in diagnosis and characterization of FMR. Echocardiography allows for assessment of valvular and ventricular structures and their interaction. FMR portends a poor prognosis, because it is frequently associated with increased morbidity and mortality. The optimal management of FMR involves an individualized approach that incorporates medical therapy and consideration of surgical, percutaneous, and resynchronization therapies according to the severity of regurgitation, presence of symptoms, option for revascularization, and the degree of ventricular remodelling.

The Utility of Systolic and Diastolic Echocardiographic Parameters for Predicting Coronary Artery Disease Burden as Defined by the SYNTAX Score

Early identification of high‐grade ischemia based on echocardiographic diastolic abnormalities may be clinically useful in the acute coronary syndrome (ACS) setting. This could provide the clinician with an awareness of the burden of coronary artery disease (CAD) before angiography is performed to allow for early intervention of suspected ischemic lesions. The objective of the study was to assess whether 2D transthoracic echocardiography (TTE)‐derived tissue Doppler imaging parameters can predict the severity of CAD in comparison with the cardiac catheterization‐derived SYNTAX score.

Novel high-sensitivity troponin assay requires higher cut-off value to separate acute myocardial infarction from non-acute myocardial infarction in a high-risk population1

PURPOSE The novel high-sensitivity troponin T assay (hs-cTnT) has been validated for diagnosing AMI in the emergency room. However its utility in high-risk in-patient populations is unknown. METHODS We retrospectively reviewed admissions to a general cardiology unit that had 2 hs-cTnT measurements in the first 12 h of presentation. We assessed 8 diagnostic algorithms that used hs-cTnT concentration and changes in concentration (including the 99th percentile cut-off of 14 ng/L) for their diagnostic utility in separating AMI patients from cardiac/nonACS and non-cardiac chest-pain patients. UA was excluded. RESULTS There were 233 patients (mean age 67 years, 153 were males (66%)) admitted over a 2 month period, with AMI diagnosed in 118 of these patients (51%). The recommended 99th percentile cut-off had modest accuracy (65%), good sensitivity (88%), and poor specificity (25%); a higher cut-off of 75 ng/L had a better diagnostic accuracy of 73%, p < 0.05. While some hs-cTnT algorithms were either highly sensitive or specific, none were both. CONCLUSION In high-risk cardiology in-patients, no hs-cTnT concentration cut-off or change more accurately diagnosed and excluded AMI, although higher cut-offs had better diagnostic utility.