Mylan C. Cohen

Single photon-emission computed tomography

The current document is an update of an earlier version of single photon emission tomography (SPECT) guidelines that was developed by the American Society of Nuclear Cardiology. Although that document was only published a few years ago, there have been significant advances in camera technology, imaging protocols, and reconstruction algorithms that prompted the need for a revised document. This publication is designed to provide imaging guidelines for physicians and technologists who are qualified to practice nuclear cardiology. While the information supplied in this document has been carefully reviewed by experts in the field, the document should not be considered medical advice or a professional service. We are cognizant that SPECT technology is evolving rapidly and that these recommendations may need further revision in the near future. Hence, the imaging guidelines described in this publication should not be used in clinical studies until they have been reviewed and approved by qualified physicians and technologists from their own particular institutions. 2. INSTRUMENTATION QUALITY ASSURANCE AND PERFORMANCE

Nonuniform Nighttime Distribution of Acute Cardiac Events A Possible Effect of Sleep States

BACKGROUND Although 250,000 myocardial infarctions and 38,000 sudden cardiac deaths occur at night annually, this public health problem is underappreciated and poorly understood. We examined whether the incidence of myocardial infarction, sudden cardiac death, and automatic implantable cardioverter-defibrillator (AICD) discharge was nonuniform, a result that may implicate physiological triggers such as sleep-state dependent changes in autonomic nervous system activity. METHODS AND RESULTS We conducted a review of the circadian pattern of the onset of myocardial infarction (n=19), sudden cardiac death (n=12), and AICD discharge (n=7). The nighttime period was chosen a priori as midnight to 5:59 AM. These reports documented 11,633 nocturnal myocardial infarctions (20% of the total myocardial infarctions), 1981 nocturnal sudden cardiac deaths (14.6% of the total sudden cardiac deaths), and 1200 nocturnal AICD discharges (15.0% of the total discharges). The distributions of myocardial infarction, sudden cardiac death, and AICD discharge were each significantly nonuniform (P<.001). The peak incidence of myocardial infarction and AICD discharge occurred between midnight and 0:59 AM, whereas the peak incidence of sudden cardiac death was between 1:00 and 1:59 AM. The trough in incidence occurred between 4:00 and 4:59 AM for sudden cardiac death and between 3:00 and 3:59 AM for myocardial infarction and AICD discharge. CONCLUSIONS Nocturnal myocardial infarction, sudden cardiac death, and AICD discharge exhibit nonuniform distributions. This finding is consistent with the hypothesis that sleep-state dependent fluctuations in autonomic nervous system activity may trigger the onset of major cardiovascular events and provides further impetus for more directly testing this hypothesis at population, individual, and mechanistic levels. A better understanding of nocturnal triggers may make it possible to reduce the incidence of myocardial infarction, ventricular tachyarrhythmias, and sudden cardiac death during the nocturnal period.

ACCF/AHA Clinical Competence Statement on Cardiac Imaging With Computed Tomography and Magnetic Resonance A Report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence and Training: Developed in Collaboration With the American Society of Echocardiography, American Society of Nuclear Cardiology, Society of Atherosclerosis Imaging, and the Society for Cardiovascular Angiography & Interventions: Endorsed by the Society of Cardiovascular Computed Tomography

ACCF/AHA Clinical Competence Statement on Cardiac Imaging With Computed Tomography and Magnetic Resonance A Report of the American College of Cardiology Foundation/ American Heart Association/American College of Physicians Task Force on Clinical Competence and Training Developed in Collaboration With the American Society of Echocardiography, American Society of Nuclear Cardiology, Society of Atherosclerosis Imaging, and the Society for Cardiovascular Angiography & Interventions Endorsed by the Society of Cardiovascular Computed Tomography

Long-term prognostic value of preoperative dipyridamole thallium imaging and clinical indexes in patients with diabetes mellitus undergoing peripheral vascular surgery

The objective of this study is to assess the prognostic impact of preoperative dipyridamole thallium imaging and clinical variables on the long-term outcome of diabetic patients undergoing peripheral vascular surgery. Complete follow-up was obtained in 101 consecutive patients with diabetes mellitus undergoing routine dipyridamole thallium scintigraphy before vascular surgery (mean 4.2 +/- 3.2 years, range 1 month to 11 years). Low risk was defined by diabetes alone with a normal resting electrocardiogram. High risk was defined as a history of angina, myocardial infarction, congestive heart failure, or resting electrocardiogram abnormalities. There were 71 deaths in 98 patients discharged alive from the hospital (median survival 4.4 years). Age, the presence of resting electrocardiogram abnormalities, and an abnormal thallium scan were independent predictors of late death. After adjusting for age >70 years and thallium abnormalities, high-risk patients had a death rate 4.8 times (95% confidence interval 1.7 to 13.4, p <0.002) greater than low-risk patients. The presence of >2 reversible thallium defects was useful in further risk stratification of both low- and high-risk patients. Low-risk patients with >2 reversible defects had a median survival of 4.0 years compared with 9.4 years in those with < or =2 reversible defects (p <0.001). Similarly, high-risk patients with < or =2 reversible defects had an intermediate median survival rate of 4.7 years compared with 1.8 years in the group with >2 reversible defects (p <0.001). Therefore, advanced age and the presence of resting electrocardiographic or thallium abnormalities identifies a subset of diabetic patients with a poor long-term outcome after vascular surgery. Combined clinical and thallium variables may identify a population in whom intensive medical or surgical interventions may be warranted to reduce both perioperative and late cardiac events.

Asystole following regadenoson infusion in stable outpatients.

Regadenoson is a selective A2A receptor agonist approved for use as a pharmacologic stress agent for myocardial perfusion imaging after several multicenter trials demonstrated its equivalence in diagnostic accuracy for the detection of coronary artery disease and a decreased incidence of serious side effects as compared to adenosine. Recently, the FDA released a safety announcement advising of the rare but serious risk of heart attack and death associated with regadenoson and adenosine in cardiac stress testing, particularly in patients with unstable angina or cardiovascular instability. We report two cases of asystole with hemodynamic collapse in stable outpatients soon after receiving a standard regadenoson injection. The prevalence of potentially life threatening bradycardia, including asystole, associated with the use of regadenoson may be greater than previously expected. These cases highlight the need for cardiac stress labs to anticipate the potential for serious side effects with all patients during the administration of coronary vasodilators.

Routine Perioperative Dipyridamole 2O1TI Imaging in Diabetic Patients Undergoing Vascular Surgery: Is it necessary?

OBJECTIVE To assess the utility of dipyridamole thallium testing in symptomatic and asymptomatic patients with diabetes undergoing vascular surgery. RESEARCH DESIGN AND METHODS Dipyridamole 201Tl myocardial scmtigraphy was performed preoperatively in 93 consecutive patients with diabetes undergoing peripheral vascular procedures. The utility of clinical and thallium variables in predicting cardiovascular complications was assessed. RESULTS Two groups of patients were identified: group A (36 patients) without clinical evidence of cardiac disease and group B (57 patients) with clinical evidence of cardiac disease. Dipyridamole thallium scans were abnormal in 21 of 36 (58%) of group A patients compared with 53 of 57 (93%) of group B patients (P < 0.0001). Compared with group B patients with perfusion defects, group A patients with perfusion abnormalities tended to have fewer defects per scan (2.7 ± 1.5 vs. 3.6 ± 1.9, P = 0.05). No perioperative cardiac complications occurred in group A patients while perioperative cardiac complications occurred in 9 of 57 (16%, 95% CI 7-28%) group B patients (P = 0.01). For the entire study population, the complication rate was 10%. CONCLUSIONS Diabetic individuals without clinical markers for coronary artery disease appear to be at low risk for adverse postoperative cardiac events after vascular surgery. Preoperative myocardial perfusion imaging may add little to cardiovascular risk assessment in this subgroup of patients with diabetes.

Perioperative and long-term prognostic value of dipyridamole Tc-99m sestamibi myocardial tomography in patients evaluated for elective vascular surgery.

BackgroundPatients with peripheral vascular disease are at increased risk for perioperative and long-term cardiac morbidity and mortality. Substantial data exist supporting the use of preoperative clinical risk stratification and planar thallium myocardial scintigraphy. Only limited data are available assessing the role of technetium-99m (Tc-99m) single photon emission computed tomography (SPECT) for preoperative evaluation in this population.>/<Methods and ResultsIn our study 153 patients who underwent peripheral vascular surgery were followed up for up to 4 years after preoperative dipyridamole Tc-99m sestamibi SPECT to determine clinical and SPECT predictors of perioperative and long-term adverse cardiac events by multivariate analysis. There were no statistically significant clinical or SPECT predictors of perioperative risk, although no perioperative events occurred in patients with normal scans. Abnormality in the left anterior descending (LAD) territory (risk ratio = 3.1; 95% confidence interval, 1.4–7.1) was the only statistically significant univariate predictor of long-term death or myocardial infarction. Only abnormality in the LAD territory appeared to improve model fit beyond clinical risk (risk ratio = 2.9; 95% confidence interval, 1.2–7.3; P = .02).>/<ConclusionsPatients with normal preoperative scans have a low risk of perioperative cardiac events and may safely undergo peripheral vascular surgery without further coronary intervention. However, scan abnormality in the LAD distribution confers poor long-term prognosis, suggesting that patients with this finding before peripheral vascular surgery should receive aggressive medical therapy and possibly invasive intervention to improve long-term survival.>/<

Cardiac Screening in the Noncardiac Surgery Patient

This article will address common cardiac conditions that require evaluation prior to noncardiac surgery, characterization of urgency and the risk associated with surgical procedures, calculation of preoperative risk assessment, indications for diagnostic testing to quantify cardiac risk, and perioperative strategies to minimize the risk of cardiac complications.

Combined supine and prone imaging acquisition in cardiac SPECT: A turn for the better

Imagine the following scenario. You are called one afternoon by your colleague in the catheterization laboratory. Your colleague sheepishly informs you that there is good news and bad news about the 65-year-old obese man whom you referred for coronary angiography because of somewhat atypical chest discomfort but a concerning inferior wall defect on pharmacologic hyperemia myocardial single-photon emission-computed tomography (SPECT). The good news is that the patient’s coronary arteries are normal. The bad news is that the patient suffered a complication of the procedure that will necessitate observation in the hospital for a day or two. You wonder whether there was anything that could have been done that may have improved the accuracy of the SPECT and obviated the need for the catheterization that resulted in an unnecessary complication. Now imagine that with a simple maneuver, without exposure to additional radiation, without additional cost to the patient, and without any new special equipment in your nuclear cardiology laboratory, you could have reduced that risk by over 50%. Would you have done it? In this issue of the Journal of Nuclear Cardiology, Taasan and coauthors report the results of a retrospective study of 934 males at a Veterans Administration Medical Center (VAMC) who underwent rest and regadenoson stress Tc-99 tetrofosmin myocardial perfusion imaging (MPI) with either supine (597 patients) or combined supine and prone image acquisition (337 patients), the laboratory routinely alternating between the two protocols. Combined supine and prone imaging increased diagnostic certainty compared with supineonly imaging, reducing the proportion of equivocal studies from 13% to 4% between the two groups (P\ .001), most equivocal studies being due to diaphragmatic attenuation. Inferior artifact size was reduced in the combined supine and prone imaging group. The appearance of prone-specific artifacts in the anterior, anteroseptal, and anterolateral walls were ‘‘small in size, mild in severity, and easy to recognize.’’ Perhaps the most important findings of the study, however, came from the subset of 116 patients who went on to have coronary angiography within 6 months of SPECT. Accuracy was increased with combined supine and prone imaging compared to supine imaging alone (area under the receiver operating curves: 0.8 ± 0.06 vs 0.57 ± 0.05, P = .004) The false-positive rate attributable to inferior wall artifacts in the combined supine and prone imaging group was less than half that of the supine-only imaging group (27% vs 64%, P\ .001). False-positive rates were 40% higher in supine-only imaging in obese patients compared to 20% higher in non-obese patients though the difference did not quite reach statistical significance (P = .06), likely related to small sample size in the subsets. The authors are to be congratulated on this study. Though not the first to demonstrate the benefit of prone imaging in combination with supine imaging, the investigation is unique in that patients were protocoled for either supine-only or combined supine and prone imaging independent of criteria such as obesity or the presence of artifact on supine imaging. Groups were compared rather than patients serving as their own controls. Though it is true that all of the patients were male as a function of the study being performed at a VAMC, which is unique, this might be considered a See related article, doi:10.1007/s12350015-0358-2.

SPECT vs CT: CT is not the first line test for the diagnosis and prognosis of stable coronary artery disease

Cardiovascular diseases have a profound impact on global health, with more people dying annually from cardiovascular diseases than from any other cause. In 2008, an estimated 7.3 million deaths globally were attributed to coronary artery disease (CAD) and this trend is expected to continue. Cardiac imaging has become an essential component in the diagnosis and management of heart disease and with the increased prevalence of heart disease, there has been a subsequent increase in the utilization of advanced cardiac imaging. In the United States, Medicare Part B data reveals that utilization increased steadily until it peaked in 2006 with the subsequent decline likely attributable, at least in part, to strategies employed to control costs (Figure 1). The utilization of cardiac-computed tomography angiography (CCTA) has also increased from 0.31 per 1,000 Medicare patients in 2000 to 1.21 in 2005. As singlephoton emission computed tomography (SPECT) became mainstream in the late 1980s, myocardial perfusion imaging has been widely regarded as the best test for the evaluation of cardiac ischemia in appropriately selected patients. More recently, however, this idea has been challenged and there is a small but growing body of literature declaring that CCTA is superior to SPECT. We contend that SPECT retains its superiority over CCTA as the first line imaging modality for establishing the diagnosis and prognosis in stable CAD. There are multiple key factors that must be considered when determining the best modality for the diagnosis and prognosis of stable CAD. The best test should be accurate and prognostic. It should be clinically relevant with the ability to guide management. The best test should be able to assess response to therapy and lead to better outcomes. It should also be widely available, applicable to a broad patient population, and safe. Finally, the best test needs to be cost-effective and add value to the system.