Noninvasive Coronary Angiography With Multislice Computed Tomography

Noninvasive Cardiology

existing limitations, an important segment of the population is at risk for heart disease in whom MSCT angiography could provide coronary anatomic information with sufficient diagnostic quality. With rapidly improving technology, and availability of 64-, 128- and 256-detector row computed tomography scanners, MSCT may well evolve from a useful complement to invasive angiography to a clinically viable alternative. The growing enthusiasm for MSCT needs to be matched with mechanisms to ensure adequate training for physicians, proper credentialing and utilization only in appropriately indicated patients. Debabrata Mukherjee

Abstracts Noninvasive Coronary Angiography With Multislice Computed Tomography Hoffmann MHK, Shi H, Schmitz BL, et al. JAMA 2005;293:2471– 8. Study Question: What are the accuracy and robustness levels of multislice computed tomography (MSCT) versus the standard of invasive coronary angiography for detection of obstructive coronary artery disease (CAD)? Methods: This prospective, single-center study included 103 consecutive patients (mean age 61.5⫾9.7 y) from November 2003 to August 2004 who underwent both invasive coronary angiography and MSCT using a scanner with 16-detector rows. Blinded results for both modalities were compared using the patient as the primary unit of analysis, with supplementary segment and vessel-based analyses. Results: A total of 1384 segments (ⱖ1.5-mm diameter) were identified by invasive coronary angiography; nondiagnostic image quality of MSCT was identified for only 88 (6.4%) of these segments, mainly due to faster heart rates. Compared with invasive coronary angiography for detection of significant lesions (⬎50% stenosis), segment-based sensitivity, specificity and positive and negative predictive values of MSCT were 95%, 98%, 87% and 99%, respectively. Quantitative comparison of MSCT and invasive coronary angiography showed good correlation (r⫽0.87; p⬍0.001), with MSCT systematically measuring greater-percentage stenoses (bias, ⫹12%). In the patient-based analysis, the area under the receiver operating characteristic curve was 0.97 (95% confidence interval, 0.90 –1.00), indicating high discriminative power to identify patients who might be candidates for revascularization (⬎50% left main artery stenosis and/or ⬎70% stenosis in any other epicardial vessel). Threshold optimization allowed either detection of these patients with 100% sensitivity at a reasonable false-positive rate (specificity, 76.5%; MSCT stenosis, ⬎66%) or optimization of both the sensitivity and specificity (⬎90%; MSCT stenosis, ⬎76%). Conclusions: The researchers concluded that MSCT provides high accuracy for noninvasive detection of suspected obstructive CAD. Perspective: The study demonstrated that MSCT shows reasonably high accuracy for detecting significant obstructive CAD in most patients. The appeal of MSCT compared with conventional coronary angiography is that it is noninvasive, avoiding most catheter-associated risks and discomforts with the exception of exposure to iodinated contrast agents and radiation. Other limitations include the potential confounding from the extent and severity of coronary calcifications, problems with in-stent visualization and compromise of image resolution in severely obese patients. Despite these

Prognostic Valve of Lung Sestamibi Uptake in Myocardial Perfusion Imaging of Patients With Known 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 at the time of myocardial perfusion imaging (MPI) confers an adverse prognosis. The objective of this study was to assess whether lung uptake of technetium-99m (99mTc) provides similar prognostic information. Methods: 99mTc MPI was performed in 718 patients. Lungto-heart ratio (LHR) was assessed at rest and stress (sLHR) and compared to standard parameters of MPI. Patients were followed for outcomes of death or acute myocardial infarction (D–MI). Results: Patients were followed for 5.6⫾1.1 years, during which 114 (16%) experienced D–MI. The sLHR was 0.36⫾0.08 in those with an event versus 0.31⫾0.06 in those without (p⬍0.00001), and the increased risk associated with sLHR was seen in subjects with normal, mild, moderate and severe MPI stress defects. Multivariable analysis identified age, previous MI, diabetes, pharmacologic (vs. exercise) stress, LV volume at stress and sLHR as independent predictors of outcome. The sLHR provided incremental information to clinical and other stress variables. Conclusions: Similar to thallium-201 lung uptake, increased sLHR with 99mTc provides prognostic information incremental to that seen with other MPI variables. Perspective: Previous work has demonstrated that increased lung uptake with thallium MPI conferred an adverse prognosis. Though the diagnostic accuracy of 99m Tc has been shown to be equivalent to that of thallium—and other variables such as MPI scores provide equivalent prognostic information—the value of increased lung uptake with this isotope had not previously been demonstrated. It appears, based on this study and others that have evaluated the diagnostic performance of 99m Tc, that this isotope when used for MPI provides

ACC CURRENT JOURNAL REVIEW September 2005

31