Noninvasive Coronary Angiography With MultisliceComputed Tomography

Hoffmann MHK, Shi H, Schmitz BL, et al. JAMA 2005;293:2471–8.

Study Question: What are the accuracy and robustness levelsof multislice computed tomography (MSCT) versus thestandard of invasive coronary angiography for detection ofobstructive coronary artery disease (CAD)?Methods: This prospective, single-center study included103 consecutive patients (mean age 61.5�9.7 y) fromNovember 2003 to August 2004 who underwent bothinvasive coronary angiography and MSCT using a scannerwith 16-detector rows. Blinded results for both modalitieswere compared using the patient as the primary unit ofanalysis, with supplementary segment and vessel-basedanalyses.Results: A total of 1384 segments (�1.5-mm diameter)were identified by invasive coronary angiography; non-diagnostic image quality of MSCT was identified for only88 (6.4%) of these segments, mainly due to faster heartrates. Compared with invasive coronary angiography fordetection of significant lesions (�50% stenosis), seg-ment-based sensitivity, specificity and positive and neg-ative predictive values of MSCT were 95%, 98%, 87%and 99%, respectively. Quantitative comparison ofMSCT and invasive coronary angiography showed goodcorrelation (r�0.87; p�0.001), with MSCT systemati-cally measuring greater-percentage stenoses (bias,�12%). In the patient-based analysis, the area under thereceiver operating characteristic curve was 0.97 (95%confidence interval, 0.90 –1.00), indicating high dis-criminative power to identify patients who might becandidates for revascularization (�50% left main arterystenosis and/or �70% stenosis in any other epicardialvessel). Threshold optimization allowed either detectionof these patients with 100% sensitivity at a reasonablefalse-positive rate (specificity, 76.5%; MSCT stenosis,�66%) or optimization of both the sensitivity and spec-ificity (�90%; MSCT stenosis, �76%).Conclusions: The researchers concluded that MSCT pro-vides high accuracy for noninvasive detection of suspectedobstructive CAD.Perspective: The study demonstrated that MSCT shows rea-sonably high accuracy for detecting significant obstructiveCAD in most patients. The appeal of MSCT compared withconventional coronary angiography is that it is noninvasive,avoiding most catheter-associated risks and discomfortswith the exception of exposure to iodinated contrast agentsand radiation. Other limitations include the potential con-founding from the extent and severity of coronary calcifica-tions, problems with in-stent visualization and compromiseof image resolution in severely obese patients. Despite these

existing limitations, an important segment of the population isat risk for heart disease in whom MSCT angiography couldprovide coronary anatomic information with sufficient diag-nostic quality. With rapidly improving technology, and avail-ability of 64-, 128- and 256-detector row computed tomogra-phy scanners, MSCT may well evolve from a usefulcomplement to invasive angiography to a clinically viablealternative. The growing enthusiasm for MSCT needs to bematched with mechanisms to ensure adequate training forphysicians, proper credentialing and utilization only in appro-priately indicated patients. Debabrata Mukherjee

Prognostic Valve of Lung Sestamibi Uptake inMyocardial Perfusion Imaging of Patients WithKnown or Suspected Coronary Artery Disease

Leslie WD, Tully SA, Yogendran MS, Ward LM, Nour KA,Metge CJ. J Am Coll Cardiol 2005;45:1676 – 82.

Study Question: Abnormal lung uptake of thallium-201 atthe time of myocardial perfusion imaging (MPI) confers anadverse prognosis. The objective of this study was to assesswhether lung uptake of technetium-99m (99mTc) providessimilar prognostic information.Methods: 99mTc MPI was performed in 718 patients. Lung-to-heart ratio (LHR) was assessed at rest and stress (sLHR)and compared to standard parameters of MPI. Patients werefollowed for outcomes of death or acute myocardial infarc-tion (D–MI).Results: Patients were followed for 5.6�1.1 years, duringwhich 114 (16%) experienced D–MI. The sLHR was0.36�0.08 in those with an event versus 0.31�0.06 inthose without (p�0.00001), and the increased risk associ-ated with sLHR was seen in subjects with normal, mild,moderate and severe MPI stress defects. Multivariable anal-ysis identified age, previous MI, diabetes, pharmacologic(vs. exercise) stress, LV volume at stress and sLHR asindependent predictors of outcome. The sLHR providedincremental information to clinical and other stress vari-ables.Conclusions: Similar to thallium-201 lung uptake, increasedsLHR with 99mTc provides prognostic information incre-mental to that seen with other MPI variables.Perspective: Previous work has demonstrated that in-creased lung uptake with thallium MPI conferred anadverse prognosis. Though the diagnostic accuracy of99mTc has been shown to be equivalent to that of thalli-um—and other variables such as MPI scores provideequivalent prognostic information—the value of in-creased lung uptake with this isotope had not previouslybeen demonstrated. It appears, based on this study andothers that have evaluated the diagnostic performance of99mTc, that this isotope when used for MPI provides

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Noninvasive CardiologyAbstracts