The establishment of "best clinical practices" founded upon evidence-based medicine has become an increasingly important priority. Frequently, management guidelines are derived from published research data and disseminated among practitioners to help optimize patient care. The ultimate clinical impact of these guidelines in the "real world," however, is often clouded by an incomplete assessment of patient outcomes throughout the continuum of health-care delivery models. In order to address this gap in clinical outcome assessment, we propose to establish the Connecticut Cardiovascular Consortium. The Consortium will consist of a collaborative partnership among all 31 Connecticut hospitals working in concert with Connecticut Office of Health Care Access (OHCA). The primary objective of the Consortium will be to assess, compare, and optimize clinical outcomes among Connecticut residents with cardiovascular disease. As an initial goal for the Consortium, we further propose to undertake a prospective, observational study of Connecticut residents who present with ST Segment Elevation Acute Myocardial Infarction (STEMI). Recent advances in pharmacologic and mechanical reperfusion for STEMI have resulted in a need to define the optimal use of these therapies in the community at large. The primary purpose of this study will be to determine the relative merits of different treatment patterns for STEMI with regard to the use of fibrinolytic therapy and percutaneous coronary intervention (PCI). Particular emphasis will be placed on assessing the relative benefits of urgent mechanical revascularization performed at the state's seven tertiary facilities with PCI capability compared to all other treatment modalities. Successful completion of this unique collaborative endeavor is expected to have significant impact on improved patient care and on current health-care policy for medical resource allocation. Moreover, continued collaboration of health-care providers within the Connecticut Cardiovascular Consortium infrastructure should serve as a useful mechanism for ongoing improvements in evidence-based cardiovascular medicine and clinical research in the state of Connecticut.

Regional and global left ventricular dysfunction caused by coronary artery disease may be reversible in a significant proportion of cases. This fact has important clinical implications. Apart from symptoms of angina and angiographic severity of coronary artery disease, potential for an improvement in left ventricular dysfunction should be taken into account when considering revascularization for the management of patients with coronary artery disease. Because left ventricular function is an important determinant of long-term prognosis in patients with coronary artery disease, identification and appropriate treatment of reversible left ventricular dysfunction may improve prognosis in many patients with significant left ventricular dysfunction. Table 1 describes the impact of myocardial viability in relation to the clinical objectives in various groups of patients with coronary artery disease. The choice of the optimal technique for the detection of myocardial viability is a matter of ongoing debate. There is no consensus in the literature for an optimal investigative approach to predict an improvement in left ventricular function following revascularization. Most of the studies in this field are based on small numbers of patients. Further studies in larger patient populations are needed. This debate is further complicated by the fact that none of the available technologies provides a quantitative estimate of viable myocardium or the extent of improvement that can be expected following revascularization. Currently the choice of technique depends on the clinical question to be answered, the local availability of the technique, and local expertise. Obviously, cost considerations may also play an important role in choice of technique. In patients with chronic stable coronary artery disease in whom reversibility of stress-induced perfusion abnormalities is the question, stress-redistribution-rest Tl-201 imaging may be the preferred modality. In patients with congestive heart failure, in whom reversibility of left ventricular function is the issue, PET imaging or rest Tl-201 imaging may provide the appropriate answer. In post-infarction patients, choice of test may depend on whether detection of residual ischemia or stunned myocardium is the issue.

UNLABELLEDTechnetium-99m-tetrofosmin is a 99mTc-labeled perfusion tracer demonstrating promise for myocardial perfusion imaging. To determine if 99mTc-tetrofosmin tracks myocardial flow over a pathophysiologic range, the initial myocardial uptake and clearance of 99mTc-tetrofosmin relative to microsphere flow were evaluated in a canine model of ischemia during pharmacological vasodilatation.METHODSSix open-chest dogs were subjected to complete left anterior descending coronary artery occlusion. Dogs were injected with 99mTc-tetrofosmin and radiolabeled microspheres during pharmacological stress. Coincident with radiotracer injection, dynamic planar imaging and arterial sampling were performed to assess 99mTc-tetrofosmin clearance from blood, myocardium, lung and liver. Fifteen minutes after injection, hearts were excised for well counting of myocardial 99mTc-tetrofosmin activity and flow.RESULTSMyocardial 99mTc-tetrofosmin activity correlated linearly with microsphere flow (r = 0.84). Relative 99mTc-tetrofosmin activity underestimated flow at higher flow ranges (> 2.0 ml/min/g) and overestimated flow in low flow ranges (< 0.2 ml/min/g). Technetium-99m-tetrofosmin cleared rapidly from the blood and was retained in the myocardium. Resting target-to-background activity ratios (heart:lung = 3.57 +/- 1.01; heart:liver = 0.58 +/- 0.04) were acceptable 10 min after injection.CONCLUSIONOur experimental data support both the validity of 99mTc-tetrofosmin as a myocardial perfusion tracer and the use of early poststress 99mTc-tetrofosmin imaging for the assessment of myocardial perfusion in man.

Background. The purpose of this study was to determine the relative image quality and interobserver variability among four readers for Tl-201 and 99mTc-labeled tetrofosmin myocardial perfusion images. 99mTc-labeled perfusion agents, with near-optimal physical characteristics for gamma camera imaging, may allow for superior image quality and improved consistency of interpretation. However, most studies to date have demonstrated only similarity in the diagnostic accuracy between technetium agents and thallium. Tetrofosmin is a recently developed 99mTc-labeled agent that has shown promising results in early clinical trials.Methods and Results. A multicenter, open-label trial was performed during which treadmill exercise thallium and tetrofosmin scintigraphy was performed within a 2-week period of each other in 216 subjects. Image quality was evaluated subjectively and scans were interpreted in a blinded, independent fashion by four readers. Perfusion abnormalities were graded as consistent with ischemia, infarction, or mixed and were described both globally and regionally. Interobserver variability was assessed by use of the kappa statistic, and receiver-operator curves were compared for each observer for the diagnostic accuracy of each agent. More tetrofosmin images were of excellent quality than with thallium (52% vs 28%; p < 0.05), and when differences in quality were noted between the agents, tetrofosmin was more often superior (p < 0.0001). The interobserver variability was lower with tetrofosmin scintigraphy because generally higher kappa values were noted, especially in the lateral wall. Higher receiver-operator curve areas indicative of improved diagnostic accuracy were noted among the four readers for tetrofosmin in 80% of vascular territories.Conclusions. 99mTc-labeled tetrofosmin scintigraphy yields images of improved quality compared with thallium, and there is an overall improvement in the consistency of image analysis associated with the use of tetrofosmin.

Evaluation of Ventricular FunctionBasic TechniquesCardiac performance, or ventricular function, can be assessed with radionuclide techniques by either of two methods. The first involves analyzing the initial transit of an intravenously administered radionuclide bolus as it traverses the central circulation. This has been called first-pass radionuclide angiocardiography, and it involves sampling for only the first 15 to 30 seconds after the injection92. The high-frequency components of the time-activity curve of radioactivity during this period are analyzed quantitatively. The radioactive indicator mixes with the blood to such an extent that the count rates of radioactivity are proportional to changes . . .