Patient management after noninvasive cardiac imaging results from SPARC (Study of myocardial perfusion and coronary anatomy imaging roles in coronary artery disease).

OBJECTIVES: This study examined short-term cardiac catheterization rates and medication changes after cardiac imaging. BACKGROUND: Noninvasive cardiac imaging is widely used in coronary artery disease, but its effects on subsequent patient management are unclear. METHODS: We assessed the 90-day post-test rates of catheterization and medication changes in a prospective registry of 1,703 patients without a documented history of coronary artery disease and an intermediate to high likelihood of coronary artery disease undergoing cardiac single-photon emission computed tomography, positron emission tomography, or 64-slice coronary computed tomography angiography. RESULTS: Baseline medication use was relatively infrequent. At 90 days, 9.6% of patients underwent catheterization. The rates of catheterization and medication changes increased in proportion to test abnormality findings. Among patients with the most severe test result findings, 38% to 61% were not referred to catheterization, 20% to 30% were not receiving aspirin, 35% to 44% were not receiving a beta-blocker, and 20% to 25% were not receiving a lipid-lowering agent at 90 days after the index test. Risk-adjusted analyses revealed that compared with stress single-photon emission computed tomography or positron emission tomography, changes in aspirin and lipid-lowering agent use was greater after computed tomography angiography, as was the 90-day catheterization referral rate in the setting of normal/nonobstructive and mildly abnormal test results. CONCLUSIONS: Overall, noninvasive testing had only a modest impact on clinical management of patients referred for clinical testing. Although post-imaging use of cardiac catheterization and medical therapy increased in proportion to the degree of abnormality findings, the frequency of catheterization and medication change suggests possible undertreatment of higher risk patients. Patients were more likely to undergo cardiac catheterization after computed tomography angiography than after single-photon emission computed tomography or positron emission tomography after normal/nonobstructive and mildly abnormal study findings. (Study of Perfusion and Anatomy's Role in Coronary Artery [CAD] [SPARC]; NCT00321399).

Reproducibility and accuracy of quantitative myocardial blood flow assessment with (82)Rb PET: comparison with (13)N-ammonia PET.

UNLABELLED: (82)Rb cardiac PET allows the assessment of myocardial perfusion with a column generator in clinics that lack a cyclotron. There is evidence that the quantitation of myocardial blood flow (MBF) and coronary flow reserve (CFR) with dynamic (82)Rb PET is feasible. The objectives of this study were to determine the accuracy and reproducibility of MBF estimates from dynamic (82)Rb PET by using our methodology for generalized factor analysis (generalized factor analysis of dynamic sequences [GFADS]) and compartment analysis. METHODS: Reproducibility was evaluated in 22 subjects undergoing dynamic rest and dipyridamole stress (82)Rb PET studies at a 2-wk interval. The inter- and intraobserver variability of MBF quantitation with dynamic (82)Rb PET was assessed with 4 repeated estimations by each of 4 observers. Accuracy was evaluated in 20 subjects undergoing dynamic rest and dipyridamole stress PET studies with (82)Rb and (13)N-ammonia, respectively. The left ventricular and right ventricular blood pool and left ventricular tissue time-activity curves were estimated by GFADS. MBF was estimated by fitting the blood pool and tissue time-activity curves to a 2-compartment kinetic model for (82)Rb and to a 3-compartment model for (13)N-ammonia. CFR was estimated as the ratio of peak MBF to baseline MBF. RESULTS: The reproducibility of the MBF estimates in repeated (82)Rb studies was very good at rest and during peak stress (R(2)= 0.935), as was the reproducibility of the CFR estimates (R(2) = 0.841). The slope of the correlation line was very close to one for the estimation of MBF (0.986) and CFR (0.960) in repeated (82)Rb studies. The intraobserver reliability was less than 3% for the estimation of MBF at rest and during peak stress as well as for the estimation of CFR. The interobserver reliabilities were 0.950 at rest and 0.975 at peak stress. The correlation between myocardial flow estimates obtained at rest and those obtained during peak stress in (82)Rb and (13)N-ammonia studies was very good (R(2) = 0.857). Bland-Altman plots comparing CFR estimated with (82)Rb and CFR estimated with (13)N-ammonia revealed an underestimation of CFR with (82)Rb compared with (13)N-ammonia; the underestimation was within +/-1.96 SD. CONCLUSION: MBF quantitation with GFADS and dynamic (82)Rb PET demonstrated excellent reproducibility as well as intra- and interobserver reliability. The accuracy of the absolute quantitation of MBF with factor and compartment analyses and dynamic (82)Rb PET was very good, compared with that achieved with (13)N-ammonia, for MBF of up to 2.5 mL/g/min.

Delayed heart rate recovery after adenosine stress testing with supplemental arm exercise predicts mortality.

BACKGROUND: Delayed heart rate (HR) recovery after treadmill exercise testing predicts mortality. Patients with suspected ischemic heart disease who cannot perform adequate treadmill exercise are typically evaluated with pharmacological stress myocardial perfusion imaging (MPI) studies, but little prognostic significance has been attributed to the hemodynamic response to vasodilator stress testing with low-level exercise. We hypothesized that a delay in HR recovery after adenosine stress testing with arm exercise is associated with increased mortality. METHODS AND RESULTS: Technetium 99m-Sestamibi MPI was performed in 1,455 consecutive patients (70 +/- 12 years, 50.2% men) with adenosine stress and supplemental arm exercise. HRs were recorded at rest, continuously during infusion, and then 5 minutes post-infusion. Delayed HR recovery was defined as a decline of < or = 12 bpm from peak HR at 5 minutes after discontinuation of the infusion. Of 1,356 patients during 5 years of follow up, there were 135 deaths (10%). Delayed HR recovery was strongly predictive of all-cause mortality (16.5% vs 5.3% in those with normal HR recovery, P < .001) with an adjusted hazard ratio of 2.5 (95% CI, 1.7-3.6; P < .001). CONCLUSION: Delayed HR recovery after adenosine stress testing with arm exercise is a readily available and powerful predictor of all-cause mortality.

Comprehensive assessment of myocardial perfusion defects, regional wall motion, and left ventricular function by using 64-section multidetector CT.

PURPOSE: To evaluate the accuracy of 64-section multidetector computed tomography (CT) for the assessment of perfusion defects (PDs), regional wall motion (RWM), and global left ventricular (LV) function. MATERIALS AND METHODS: All myocardial infarction (MI) patients signed informed consent. The IRB approved the study and it was HIPAA-compliant. Cardiac multidetector CT was performed in 102 patients (34 with recent acute MI and 68 without). Multidetector CT images were analyzed for myocardial PD, RWM abnormalities, and LV function. Global LV function and RWM were compared with transthoracic echocardiography (TTE) by using multidetector CT. PD was detected by using multidetector CT and was correlated with cardiac biomarkers and single photon emission CT (SPECT) myocardial perfusion imaging. Multidetector CT diagnosis of acute MI was made on the basis of matching the presence of PD with RWM abnormalities compared with clinical evaluation. RESULTS: Correlation between multidetector CT and TTE for global function (r = 0.68) and RWM (kappa = 0.79) was good. The size of PD on multidetector CT had a moderate correlation against SPECT (r = 0.48, -7% +/- 9). There was good to excellent correlation between cardiac biomarkers and the percentage infarct size by using multidetector CT (r = 0.82 for creatinine phosphokinase, r = 0.76 for creatinine phosphokinase of the muscle band, and r = 0.75 for troponin). For detection of acute MI in patients, multidetector CT sensitivity was 94% (32 of 34) and specificity was 97% (66 of 68). Multidetector CT had an excellent interobserver reliability for ejection fraction quantification (r = 0.83), as compared with TTE (r = 0.68). CONCLUSION: Patients with acute MI can be identified by using multidetector CT on the basis of RWM abnormalities and PD.

Importance of systematic review of rotating projection images from Tc99m-sestamibi cardiac perfusion imaging for noncardiac findings.

PURPOSE: To test the hypothesis that the observed incidence of important noncardiac findings (NCFs) on myocardial perfusion imaging increases significantly when readers systematically review all rotating projectional images. METHODS: We prospectively studied NCF reported from a population of 7658 stress cardiac perfusion studies using a single-agent same-day protocol by a review of rotating projectional images. The incidence of NCF was evaluated for both an ensemble of general clinical readers and for a subset of readers who systematically review all rotating projectional images. The clinical validation of NCF was determined first from an evaluation of the electronic medical record and then after direct communication with the primary physicians. RESULTS: NCF incidence for general clinical readers was 0.08%, increasing significantly to 0.82% for readers who systematically review all rotating projectional images (P=0.0013). The spectrum of pathology was diverse, particularly including significant findings such as previously unknown cancers. A total of 53 NCFs were detected, of which clinical follow-up found a corresponding diagnosis in 35 cases (66%). Of these, 43% were previously known, 20% new, and 37% false positives. Thirty-four percent of all NCF had no follow-up, mainly because of lack of additional diagnostic tests. CONCLUSION: NCFs are infrequent but often clinically important findings, whose detection is significantly enhanced by systematic reviews of all rotating projectional images.

Potential indications for coronary angiography by computed tomography.

Recent advances in computed tomography technology have made possible angiographic images of relatively small, moving vascular structures such as the coronary arteries. Computed tomographic coronary angiography is an exciting modality which has several obvious advantages over invasive catheterization, such as its relatively noninvasive nature and rapid speed of acquisition. However, significant drawbacks still exist, including limitations of spatial and temporal resolution and radiation exposure. Computed tomographic coronary angiography appears best suited as a diagnostic modality for the patient population with a low-to-moderate pretest probability of coronary artery disease, and for specific indications such as the imaging of coronary anomalies and bypass grafts and before biventricular pacemaker placement and atrial fibrillation ablation.

Integration of clinical and imaging data to predict the presence of coronary artery disease with the use of neural networks.

AIM: To establish proof of the principle that a computer-based neural network method can be employed that will enhance diagnostic accuracy vis-a-vis image analysis alone in the interpretation of treadmill exercise tests performed in conjunction with myocardial perfusion imaging. MATERIALS AND METHODS: One-hundred-and-two patients underwent myocardial perfusion imaging in association with the standard Bruce protocol. Twenty objective parameters describing each patient's exercise physiology, general clinical status and image appearance were used to train an artificial neural network. Classification accuracy of the neural network and clinical interpretation was determined by coronary angiography. We evaluated the ability of the neural network to integrate clinical, exercise and imaging data to determine the likelihood of coronary artery disease and compared these results with an optimized method of clinical image interpretation, which made use of all available clinical, angiographic and stress test data. RESULTS: The artificial neural network had a sensitivity of 88% and a specificity of 65% for detection of ischemic heart disease and was comparable to that of the optimized clinical method (sensitivity 80%, specificity 69%). Incorporation of clinical and exercise data significantly improved the predictive accuracy of the network compared to a network based on image data alone (P<0.05). CONCLUSION: The results show a computer-based neural network can perform as well as expert readers working under optimal conditions including full knowledge of the patient's clinical, prior angiographic and stress test data. Thus, the method is promising as a diagnostic aid to the recognition of ischemic heart disease in the clinical setting of treadmill exercise testing in conjunction with myocardial perfusion imaging.