MD Conference Express ACC 2012 - (Page 28)
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which ensures high quality images and low radiation exposure. Importantly, this preparation is not possible in all patients, and those with insufficient heart rate control cannot be adequately evaluated with this modality. Also, not all patients will benefit from CCTA, Dr. Karlsberg emphasized. CCTA is not appropriate for patients with high-risk ACS, known obstructive disease, renal impairment, an uncontrolled heart rate after beta-blockers or arrhythmias, an allergy to contrast medium, or severe coronary calcium or when patients are not cooperative and cannot hold their breath. Furthermore, there are some patients in whom, based on clinical judgment, absolutely no further testing is required. An optimal pathway has not been established yet, but a large group of low-to-intermediate risk patients may substantially benefit from this new approach. Consequently, this recently released research paves the way for appropriate and more widely adopted implementation of CCTA in the ED for rapid evaluation of chest pain. Figure 1. CCTA from a 70-Year-Old Man with Chest Pain, Modest Risk Factors, and No Known Previous CAD.
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Heart Institute, Ottawa, Ontario, Canada. A recent metaanalysis found an average sensitivity of 98% across several single-center studies [Paech DC et al. BMC Cardiovasc Disord 2011]. The first results from multicenter trials showed variable operating characteristics, with a lower mean sensitivity (90%). Dr. Chow pointed out that one study showed that sensitivity and negative predictive value vary widely according to center and that this highlights the need for individual centers to perform validation testing. More recent multicenter studies have demonstrated the independent and incremental value of CCTA in predicting all-cause mortality among symptomatic patients with CAD [Min JK et al. JACC 2007; Ostrom MP et al. JACC 2008]. Increasing severity of disease on CCTA has consistently been associated with worse outcomes, and the risk for death is extremely low for patients with no evidence of CAD on CCTA. In his own study, Dr. Chow and colleagues analyzed data from an international multicenter registry (CONFIRM) in 27,125 patients and found that CCTA conveys prognostic information above left ventricular ejection fraction [Chow BJ et al. Circ Cardiovasc Imaging 2011]. The annual mortality for patients with no evidence of CAD on CCTA was 0.65%, compared with an annualized mortality rate of 1.14% for patients with nonobstructive CAD and 2.63% for patients with high-risk CAD. These data confirm the results of prior studies that have shown a similar association between burden of CAD and outcomes using other imaging modalities (eg, coronary angiography, nuclear imaging). Coronary Artery Calcium (CAC) In light of the value of CCTA, is there still a role for CAC testing? Although CCTA is the noninvasive test of choice in many cases, the test is more expensive and time-intensive, requires greater skill for interpretation, and uses higher doses of radiation, according to Khurram Nasir, MD, MPH, Yale University School of Medicine, New Haven, Connecticut, USA. Dr. Nasir said that CAC testing has a role in testing asymptomatic and symptomatic patients with varying levels of risk and is of little value for people who are at very high risk for CAD. An important feature of CAC is that the absence of CAC indicates a very low risk for CAD. Large studies have shown that the rate of CV disease events or death at 4 to 5 years is less than 1% for patients with a CAC score of 0 [Sarwar A et al. JACC Imaging 2009; Budoff M et al. Am Heart J 2009]. The results of a 2011 study that involved the CONFIRM registry showed that among
CCTA was performed, and hours later, a minimal troponin leak was determined. CCTA defined the Hounsfield Units (HU) characteristic of the contrast agent 425 HU, dense calcified plaque 928 HU, noncalcified plaque 115 HU, and low-density (potentially vulnerable) plaque 45 HU. Positive remodeling, another characteristic of vulnerability, was present. The culprit narrowing was 5.5 mm from the left main, providing an invasive coronary angiography strategy for subsequent successful stenting of the proximal left anterior descending coronary artery, which was expediently performed (Cedars Sinai Medical Center, Los Angeles California). With permission from RP Karlsberg, MD.
Prognostic Value of CCTA In addition to its high negative predictive value, CCTA has high sensitivity, said Benjamin Chow, MD, FRCPC, FACC, FASNC, FSCCT, Co-Director of Cardiac Radiology and Director of Cardiovascular CT, University of Ottawa
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May 2012
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Table of Contents for the Digital Edition of MD Conference Express ACC 2012
MD Conference Express ACC 2012
Table of Contents
Treatment of AMI in the Post-Herrick Era
The State of Hypertension Guidelines: 2012
ACRIN PA 4005: Coronary CTA in the ED Identifies Low-Risk Patients and Shortens Length of Stay
One-Year STAMPEDE Trial Results
TAVR Associated with Increased Late Mortality from Paravalvular Regurgitation
The CABG Surgery Off- or On- Pump- Revascularization Study (CORONARY)
The Moderate PE Treated with Thrombolysis Study (MOPETT)
Pacemaker Therapy In Patients With Neurally Mediated Syncope and Documented Asystole
Outcomes from the BRIDGE-ACS Trial
ROMICAT II: More Data Evaluating CT-First for Acute Chest Pain ED Triage
Elective PCI at Community Hospitals With Versus Without On-Site Surgery
Results from the TRA 2P-TIMI 50 Trial
The HOST-ASSURE Randomized Trial
New Monoclonal Antibody to PCSK9 Markedly Lowers LDL-C in Patients on Atorvastatin
Oral Rivaroxaban Alone for Symptomatic PE
Neutral Outcomes But Important Insights From FOCUS-CCTRN
Imaging
STEMI
Acute Coronary Syndrome
Antiplatelet Therapy
New Anti-Diabetes Agents Offer Promise in the Fight Against CVD
The New Hypertrophic Cardiomyopathy Practice Guidelines
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