Abdulmassih S. Iskandrian’s research while affiliated with York College of Pennsylvania and other places

This study examined the imaging results and kinetics of technetium 99m teboroxime after its intracoronary injection during papaverine-induced coronary hyperemia in patients with one-vessel disease before and after coronary angioplasty. Thirteen patients with > or = 90% diameter stenosis of either the left anterior descending or the left circumflex coronary artery were included. Two patients were excluded because of ventricular tachycardia during papaverine injection in one patient and unsuccessful angioplasty in the second patient. One mCi of technetium 99m teboroxime was injected into the left main coronary artery during coronary hyperemia induced by intracoronary injection of papaverine. Dynamic acquisition in a frame mode (20 sec/frame) was performed for 5 minutes in the left anterior oblique projection with a multicrystal gamma camera before and after successful angioplasty. Ischemic:normal count ratio increased from 0.75 +/- 0.4 before to 1.00 +/- 0.50 after angioplasty (p < 0.1). The T 1/2 of teboroxime was 6.5 +/- 1.5 min in the normal zone and 7.2 +/- 1.9 min in the ischemic zone (p, NS). Perfusion defects were visible in the territory of the stenosed coronary artery in 9 of 11 patients before angioplasty and in 7 of 11 patients after angioplasty. The image quality was excellent in all studies. Thus this study shows that performing dynamic imaging with intracoronary injection of technetium 99m teboroxime is feasible. This technique may be useful to study the impact of angioplasty on coronary flow and tracer kinetics.

Myocardial hibernation is hypoperfused dysfunctional myocardium that has the potential to recover function after coronary revascularization. Although recovery of regional function after revascularization is the gold standard for assessing the diagnostic accuracy of various techniques, improvements of EF, symptoms, and survival are fundamental end points. Despite important differences in the markers of viability by positron-emission tomography, single-photon emission tomography, two-dimensional echocardiography, and magnetic resonance imaging, their positive and negative predictive values in nonrandomized studies are fairly comparable. Assessment of myocardial viability may be clinically important in many patients but especially in those with EF < 30% and congestive heart failure. The degree of improvement in EF after coronary revascularization depends on the extent of hibernation, the suitability of coronary structure for revascularization, the lack of perioperative infarction, the completeness of revascularization, and the long-term patency of grafts.

Previous studies show that stress perfusion imaging provides independent and incremental information in risk assessment. These studies, however, did not include quantitative methods. This study examined the predictors of prognosis using quantitative data from treadmill exercise, coronary angiography, and exercise SPECT thallium-201 imaging in medically treated patients with stable symptoms.There were 732 medically treated patients (excluded were patients with recent revascularization or acute ischemic syndromes) who had coronary angiography and exercise SPECT thallium imaging. There were 69 events (cardiac death or nonfatal MI) at a mean follow-up time of 41 ± 22 months. The prognostic values of the clinical characteristics, treadmill exercise score, Gensini score, and SPECT thallium score were examined by Cox survival analysis. Univariate analysis showed that the chi-square of SPECT (χ2 = 15, p = 0.0001) was higher than that of the Gensini score (χ2 = 5, p = 0.03) and the treadmill exercise score (χ2 = 1, p = NS). Actuarial life-table analysis showed that SPECT provided the best separation between groups at high and low risk. The event rates were 13% versus 4% (p = 0.001) by SPECT; 11% versus 7% (p = 0.05) by Gensini score, and 10% versus 7% (p = NS) by treadmill exercise score in groups at high and low risk, respectively. Further, SPECT contained most of the prognostic information provided by coronary angiography. The area under the ROC curve was significantly larger for SPECT than for the Gensini and treadmill exercise scores (p = 0.05).Thus in medically treated patients with stable symptoms, quantitative assessment of exercise perfusion defect size by SPECT is the most important predictor of prognosis; it is significantly more important than the Gensini score (which represents the extent and severity of coronary artery disease) and treadmill exercise score.

Because of their vascularity, lung tumors show uptake of sestamibi and 201Tl. In this patient the lung tumor could easily have been missed if the raw data were not reviewed.

Previous studies show that rest-redistribution thallium imaging is useful in the assessment of myocardial viability. The impact of such studies on patient outcome is not well defined. This study examined the prognostic value of tomographic rest-redistribution 201T1 imaging in 81 medically treated patients with coronary artery disease and left ventricular dysfunction. Rest-redistribution single-photon emission computed tomographic images were obtained and analyzed quantitatively. The segmental thallium uptake (20 segments per patient) was interpreted as normal, reversible defect, mild to moderate fixed defect, or severe fixed defect. The thallium images were abnormal in 80 patients, with no redistribution (no ischemia) in 43 patients and redistribution (ischemia) in 38 patients. The left ventricular ejection fraction was 27% +/- 8% in patients with no redistribution and 26% +/- 7% in patients with redistribution (difference not significant). In patients with no ischemia, there were 7 +/- 5 severe fixed defects and 5 +/- 4 mild to moderate fixed defects per patient. In patients with ischemia there were 7 +/- 4 reversible defects, 3 +/- 3 mild to moderate fixed defects, and 5 +/- 4 severe fixed defects per patient. The number of any abnormal segments was 11 +/- 5 in patients with no ischemia and 14 +/- 4 in patients with ischemia (p = 0.03). During a mean follow-up of 31 +/- 24 months, there were 11 cardiac deaths in patients with no ischemia (26%) and 22 in patients with ischemia (58%); the survival rate was worse in patients with than without ischemia (p < 0.05). Multivariate Cox survival analysis on important clinical, angiographic, and thallium variables showed that the presence of redistribution was an independent predictor of death (x2 = 5; p = 0.03). Patients with left ventricular dysfunction and redistribution on rest thallium imaging, a marker of hibernating myocardium, have a higher mortality rate with medical therapy than do patients with a comparable degree of left ventricular dysfunction but with fixed defects only. Thus observations similar to those made with positron emission tomography can be made in a much more straightforward, simple, and probably cost-effective manner with single-photon emission computed tomography.

During a mean follow-up of 19 months, 40 of 269 patients with severe left ventricular dysfunction died from cardiac causes after coronary artery bypass grafting (19 in the perioperative period and 21 in the follow-up period). Better screening to identify high-risk patients as well as those who may benefit the most from coronary artery bypass grafting is necessary.

Objectives: This study sought to evaluate the efficacy and safety of arbutamine when used in conjunction with thallium-201 single-photon emission computed tomography (SPECT) in a multicenter trial and to compare arbutamine stress and treadmill exercise thallium-201 SPECT for diagnostic sensitivity and myocardial perfusion pattern. Background: Arbutamine is a potent beta-agonist developed specifically for pharmacologic stress testing. Methods: Arbutamine was administered by a novel computerized closed-loop device that measures heart rate and adjusts arbutamine infusion to achieve a selected rate of heart rate increase toward a predetermined limit. The cohort included 184 patients who underwent arbutamine stress testing, of whom 122 (catheterization group) had angiographically defined coronary artery disease ( > or = 50% diameter stenosis of a major coronary artery), and 62 had a low pretest likelihood of coronary artery disease (low likelihood group). A subset of 69 patients from the catheterization group underwent both arbutamine and exercise stress testing. Results: Hemodynamic responses during arbutamine and exercise stress testing demonstrated no significant difference in percent increase in heart rate (81% vs. 76%) or systolic blood pressure (26% vs. 30%). The sensitivity for detecting coronary artery disease ( > or = 50% stenosis) using arbutamine thallium-201 SPECT was 87% (95% for detecting > or = 70% stenoses), and the normalcy rate in the low likelihood group was 90%. In patients completing both arbutamine and exercise stress testing, thallium-201 SPECT sensitivity for detecting coronary artery disease ( > or = 50% stenosis) was 94% and 97% (p = NS), respectively Furthermore, SPECT segmental visual score agreement (defect vs. no defect) showed a concordance of 92% between arbutamine and exercise results (kappa 0.80, p < 0.001). The stress thallium-201 SPECT segmental scores showed 83% exact agreement (kappa 0.69, p < 0.001), and analysis of the reversibility of segments with stress perfusion defects demonstrated 86% exact agreement (kappa 0.68, p < 0.001). In general, side effects associated with arbutamine were well tolerated and resolved with discontinuation of infusion. Conclusions: Arbutamine, administered by a closed-loop feed-back system was shown to be a safe and effective pharmacologic stress agent. Arbutamine stress thallium-201 SPECT appears to be accurate for the diagnosis of coronary artery disease with a diagnostic efficacy similar to that of treadmill exercise thallium-201 studies.

During the Mueller maneuver, there is a decrease in intrathoracic pressure and an increase in transmural left ventricular pressure. The changes in loading conditions cause transient left ventricular dysfunction. This study examined the effects of the Mueller maneuver on left ventricular performance using tantalum (Ta)-178 (half-life 9.3 min) and a multiwire gamma camera. First-pass radionuclide angiograms were obtained at baseline and during Mueller maneuver in 41 patients aged 58 +/- 10 years. In 34 patients, stress single photon emission computed tomography (SPECT) myocardial perfusion imaging with thallium-201 or sestamibi was also performed. Hemodynamic measurements during the Mueller maneuver (n = 10) showed a decrease in systemic pressure (139 +/- 25 mm Hg vs 123 +/- 24 mm Hg, p < 0.001) and pulmonary artery pressure (24 +/- 6 mm Hg vs 14 +/- 12 mm Hg, p = 0.01) and an increase in heart rate (67 +/- 10 bpm vs 75 +/- 14 beats/min, p = 0.001). Among the 34 patients who had perfusion imaging, the left ventricular ejection fraction remained unchanged or increased in 17 patients (group 1) (48% +/- 19% vs 49% +/- 21%, p not significant) and decreased (> or = 5%) in 17 patients (group 2) (55% +/- 13% vs 40% +/- 16%, p = 0.001). The stress SPECT images showed no or only fixed defects in 11 (65%) patients in group 1 and 3 (18%) patients in group 2 (p = 0.02), and reversible defects in 6 (35%) patients in group 1 and 14 (82%) patients in group 2 (p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)