Prem Soman

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

Echocardiography-Guided Left Ventricular Lead Placement for Cardiac Resynchronization Therapy Results of the Speckle Tracking Assisted Resynchronization Therapy for Electrode Region Trial

Background— Cardiac resynchronization therapy improves mortality and morbidity in patients with heart failure (HF) with wide QRS complex and diminished left ventricular (LV) function, but response is variable. Methods and Results— The Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) was a prospective, double-blind, randomized controlled trial testing the hypothesis that an incremental benefit to cardiac resynchronization therapy would be gained by echo-guided (EG) transvenous LV lead placement versus a routine fluoroscopic approach. EG LV lead placement was attempted at the site of latest time to peak radial strain by speckle tracking echocardiography. The prespecified primary end point was first HF hospitalization or death. Of 187 New York Heart Association class II to IV patients with HF (62% ischemic; ejection fraction 26±6%; QRS 159±27 ms), 110 were randomized to EG and 77 to routine strategies. Primary events included 30 deaths and 37 HF hospitalizations over 1.8 years. Using intention-to-treat, patients randomized to an EG strategy had a significantly more favorable event-free survival (hazard ratio, 0.48; 95% confidence interval, 0.28–0.82; P =0.006). Exact or adjacent concordance of LV lead with latest site could be achieved in 85% of the EG group and occurred fortuitously in 66% of controls ( P =0.010) and was associated with an improvement in event-free survival (hazard ratio, 0.40; 95% confidence interval, 0.22–0.71; P =0.002). Conclusions— A strategy of EG LV lead placement for cardiac resynchronization therapy improved patient outcomes by reducing the combined risk of death or HF hospitalizations and has implications for delivery of cardiac resynchronization therapy. Clinical Trial Registration— URL: . Unique identifier: [NCT00156390][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00156390&atom=%2Fcirchf%2F6%2F3%2F427.atomBackground—Cardiac resynchronization therapy improves mortality and morbidity in patients with heart failure (HF) with wide QRS complex and diminished left ventricular (LV) function, but response is variable. Methods and Results—The Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) was a prospective, double-blind, randomized controlled trial testing the hypothesis that an incremental benefit to cardiac resynchronization therapy would be gained by echo-guided (EG) transvenous LV lead placement versus a routine fluoroscopic approach. EG LV lead placement was attempted at the site of latest time to peak radial strain by speckle tracking echocardiography. The prespecified primary end point was first HF hospitalization or death. Of 187 New York Heart Association class II to IV patients with HF (62% ischemic; ejection fraction 26±6%; QRS 159±27 ms), 110 were randomized to EG and 77 to routine strategies. Primary events included 30 deaths and 37 HF hospitalizations over 1.8 years. Using intention-to-treat, patients randomized to an EG strategy had a significantly more favorable event-free survival (hazard ratio, 0.48; 95% confidence interval, 0.28–0.82; P=0.006). Exact or adjacent concordance of LV lead with latest site could be achieved in 85% of the EG group and occurred fortuitously in 66% of controls (P=0.010) and was associated with an improvement in event-free survival (hazard ratio, 0.40; 95% confidence interval, 0.22–0.71; P=0.002). Conclusions—A strategy of EG LV lead placement for cardiac resynchronization therapy improved patient outcomes by reducing the combined risk of death or HF hospitalizations and has implications for delivery of cardiac resynchronization therapy. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00156390.

Impact of scar burden by single-photon emission computed tomography myocardial perfusion imaging on patient outcomes following cardiac resynchronization therapy.

AIMS Ischaemic heart disease negatively impacts response to cardiac resynchronization therapy (CRT), yet the impact of infarct scar burden on clinical outcomes and its interaction with mechanical dyssynchrony have not been well described. METHODS AND RESULTS We studied 620 NYHA classes III-IV heart failure patients with ejection fraction (EF) ≤ 35% and QRS duration ≥120 ms referred for CRT. Included were 190 ischaemic cardiomyopathy (ICM) CRT recipients with scar burden quantified by rest-redistribution Tl(201) myocardial perfusion imaging using a 17-segment (0 = normal to 4 = absence of uptake) summed rest score (SRS). Non-ICM (NICM) CRT recipients (n = 380) and 50 patients referred for CRT with unsuccessful LV lead implant comprised the comparison groups. Echocardiographic dyssynchrony analysis was performed in a subgroup of 150 patients. Follow-up left ventricular EF (LVEF) and volumes were examined at 7 ± 3 months in 143 patients. The outcome of death, cardiac transplant, or mechanical circulatory support was assessed in all. Over 2.1 ± 1.6 years, ICM patients had significantly worse survival and less LVEF improvement than NICM patients (P < 0.01). Ischaemic cardiomyopathy patients with low scar burden (SRS < 27) had favourable survival and LVEF improvement, similar to NICM patients. A high scar burden (SRS ≥ 27) was associated with reduced survival and lack of LV functional improvement (P ≤ 0.01), similar to those with unsuccessful LV lead implant, whereas baseline dyssynchrony was not predictive of outcome in these patients. CONCLUSION Extensive scar burden in ICM patients unfavourably affected clinical and LV functional outcomes after CRT, regardless of baseline dyssynchrony measures. Patients with ICM and lower scar burden had significantly better outcomes, similar to NICM patients.

Echocardiography-Guided Left Ventricular Lead Placement for Cardiac Resynchronization TherapyClinical Perspective

Background— Cardiac resynchronization therapy improves mortality and morbidity in patients with heart failure (HF) with wide QRS complex and diminished left ventricular (LV) function, but response is variable. Methods and Results— The Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) was a prospective, double-blind, randomized controlled trial testing the hypothesis that an incremental benefit to cardiac resynchronization therapy would be gained by echo-guided (EG) transvenous LV lead placement versus a routine fluoroscopic approach. EG LV lead placement was attempted at the site of latest time to peak radial strain by speckle tracking echocardiography. The prespecified primary end point was first HF hospitalization or death. Of 187 New York Heart Association class II to IV patients with HF (62% ischemic; ejection fraction 26±6%; QRS 159±27 ms), 110 were randomized to EG and 77 to routine strategies. Primary events included 30 deaths and 37 HF hospitalizations over 1.8 years. Using intention-to-treat, patients randomized to an EG strategy had a significantly more favorable event-free survival (hazard ratio, 0.48; 95% confidence interval, 0.28–0.82; P =0.006). Exact or adjacent concordance of LV lead with latest site could be achieved in 85% of the EG group and occurred fortuitously in 66% of controls ( P =0.010) and was associated with an improvement in event-free survival (hazard ratio, 0.40; 95% confidence interval, 0.22–0.71; P =0.002). Conclusions— A strategy of EG LV lead placement for cardiac resynchronization therapy improved patient outcomes by reducing the combined risk of death or HF hospitalizations and has implications for delivery of cardiac resynchronization therapy. Clinical Trial Registration— URL: . Unique identifier: [NCT00156390][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00156390&atom=%2Fcirchf%2F6%2F3%2F427.atomBackground—Cardiac resynchronization therapy improves mortality and morbidity in patients with heart failure (HF) with wide QRS complex and diminished left ventricular (LV) function, but response is variable. Methods and Results—The Speckle Tracking Assisted Resynchronization Therapy for Electrode Region (STARTER) was a prospective, double-blind, randomized controlled trial testing the hypothesis that an incremental benefit to cardiac resynchronization therapy would be gained by echo-guided (EG) transvenous LV lead placement versus a routine fluoroscopic approach. EG LV lead placement was attempted at the site of latest time to peak radial strain by speckle tracking echocardiography. The prespecified primary end point was first HF hospitalization or death. Of 187 New York Heart Association class II to IV patients with HF (62% ischemic; ejection fraction 26±6%; QRS 159±27 ms), 110 were randomized to EG and 77 to routine strategies. Primary events included 30 deaths and 37 HF hospitalizations over 1.8 years. Using intention-to-treat, patients randomized to an EG strategy had a significantly more favorable event-free survival (hazard ratio, 0.48; 95% confidence interval, 0.28–0.82; P=0.006). Exact or adjacent concordance of LV lead with latest site could be achieved in 85% of the EG group and occurred fortuitously in 66% of controls (P=0.010) and was associated with an improvement in event-free survival (hazard ratio, 0.40; 95% confidence interval, 0.22–0.71; P=0.002). Conclusions—A strategy of EG LV lead placement for cardiac resynchronization therapy improved patient outcomes by reducing the combined risk of death or HF hospitalizations and has implications for delivery of cardiac resynchronization therapy. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00156390.

2013 ACCF/ACR/ASE/ASNC/SCCT/SCMR appropriate utilization of cardiovascular imaging in heart failure: A joint report of the American college of radiology appropriateness criteria committee and the American college of cardiology foundation appropriate use criteria task force

Peter Alagona, MD[⁎][1] Gerard Aurigemma, MD[‡][2] Javed Butler, MD, MPH[§][3] Don Casey, MD, MPH, MBA[∥][4] Ricardo Cury, MD[#][5] Scott Flamm, MD[¶][6] Tim Gardner, MD[⁎⁎][7] Rajesh Krishnamurthy, MD[††][8] Joseph Messer, MD[⁎][1] Michael W. Rich, MD[‡‡][9] Henry

A prospective pilot study to evaluate the relationship between acute change in left ventricular synchrony after cardiac resynchronization therapy and patient outcome using a single-injection gated SPECT protocol.

Background— There are ongoing efforts to optimize patient selection criteria for cardiac resynchronization therapy (CRT). In this regard, the relationship between acute change in left ventricular synchrony (LV) after CRT and patient outcome remains undefined. Methods and Results— A novel protocol was designed to evaluate acute change in left LV synchrony after CRT using phase analysis of standard gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging with a single injection of radiotracer and prospectively applied to 44 patients undergoing CRT. Immediately after CRT, 18 (41%), 11 (25%), and 15 (34%) patients had an improvement, no change, or a worsening in LV synchrony. An algorithm incorporating the presence of baseline dyssynchrony, myocardial scar burden, and lead concordance predicted acute improvement or no change in LV synchrony with 72% sensitivity, 93% specificity, 96% positive predictive value, and 64% negative predictive value and had 96% negative predictive value for acute deterioration in synchrony. Over a follow-up period of 9.6±6.8 months, patients who had an acute deterioration in synchrony after CRT had a higher composite event rate of death, heart failure hospitalizations, appropriate defibrillator discharges, and CRT device deactivation for worsening heart failure symptoms, compared with patients who had an improvement or no change [hazard ratio, 4.6 (1.3 to 16.0); log rank test; P=0.003]. Conclusions— In this single-center pilot study, phase analysis of gated SPECT was successfully used to predict acute change in LV synchrony and patient outcome after CRT.

Cardiovascular nuclear imaging: Balancing proven clinical value and potential radiation risk

The debate on the potential risk of radiation exposure from diagnostic imaging tests highlights the importance of balancing the demonstrated clinical benefit and the theoretic risk of cardiovascular imaging studies. The Cardiovascular Council of the Society of Nuclear Medicine upholds the responsible application of imaging studies that use radiotracers associated with relatively small amounts of ionizing radiation. Radionuclide-based cardiac imaging studies, including myocardial perfusion imaging (MPI), provide accurate diagnostic and prognostic information about patients with suspected or known heart disease. There is a large body of scientific evidence on the clinical value of MPI, based on studies performed on many thousands of patients. On the basis of this information, appropriate-use criteria and guidelines were developed and endorsed by the Society of Nuclear Medicine and other professional societies, including the American College of Cardiology, American Heart Association, and American Society of Nuclear Cardiology (1). Cardiovascular nuclear medicine studies provide highly sensitive and specific tests that may be indicated for the evaluation of diagnosis, prognosis, and treatment response of coronary artery disease, as well as for selection of patients who benefit from revascularization. The value and justification of MPI for risk assessment is based on large observational outcome studies that demonstrate accurate risk stratification with radionuclide-based MPI in populations with an intermediate pretest risk. The incremental prognostic value of SPECT MPI is greater than that of the exercise electrocardiography stress test or coronary angiography. The cost effectiveness of MPI as a gatekeeper to coronary angiography has been established after being carefully and extensively studied. Several recent publications have raised concern about the potential harmful effects of ionizing radiation associated with cardiac imaging. Review of the measurement of radiation and associated biologic effects can help put this issue into reasonable perspective. Radiation effective dose is a measure used to estimate the biologic effects of radiation. Measuring the radiation effective dose associated with diagnostic imaging is complex and imprecise and often results in varying estimates among experts (2). A typical effective dose for a rest–stress same-day SPECT scan using 99mTclabeled agents (1,110 MBq [30 mCi] stress, 370 MBq [10 mCi] rest), the most commonly used MPI protocol, is approximately 10 mSv. Other agents and protocols are associated with a wide range of radiation exposure (2). In comparison, exposure to radiation from natural sources amounts to approximately 3 mSv annually. The risk of a fatal malignancy from medical imaging–related radiation is difficult to estimate precisely but is likely small and difficult to discern from the background risk of natural malignancies. The theoretic lifetime attributable risk of cancer from a rest and stress 99mTc-based MPI study for individuals age 35 y or older is less than 1.5 in 1,000 (3). This risk is less in older patients, who constitute most patients evaluated for coronary artery disease. The estimated risk of fatal malignancy from a typical MPI study is 0.5 per 1,000 individuals, compared with a risk of death from natural cancer of 212 per 1,000 (4). The potential risk of cancer must be balanced against the risk of death, myocardial infarction, or other morbid vascular events in an appropriately referred population. This risk ranges from 1% to 10% or more per year and is orders of magnitude greater than the potential lifetime risk of cancer and death from cancer attributable to cardiovascular nuclear medicine studies. Assessment of risk-to-benefit ratio mandates a good understanding of the clinical characteristics of the patient, including risk factors for coronary artery disease, prior history of coronary artery disease, and left ventricular function. For example, given the substantially higher risk of morbid coronary events or heart failure in patients with left ventricular dysfunction, higher radiation exposure associated with 201Tl or 18F-FDG for radionuclide assessment of viability is readily justifiable. In this context, one must not fail to take into account the risks of missing important diagnostic information by not performing a test (which could potentially influence near-term management and outcomes) because of a theoretic concern about a long-term small risk of malignancy. Similarly, assessment of the significance of radiation exposure risk in population-based studies would be challenging without information on the overall pool from which the patients are selected and how representative they are of the total patient population. While the potential long-term radiation risk associated with cardiovascular nuclear medicine studies is debated (5), Received Mar. 17, 2011; revision accepted Mar. 24, 2011. For correspondence or reprints contact: Mehran M. Sadeghi, Yale University School of Medicine, 950 Campbell Ave., West Haven, CT 06516. E-mail: mehran.sadeghi@yale.edu COPYRIGHT a 2011 by the Society of Nuclear Medicine, Inc. DOI: 10.2967/jnumed.111.090654

Myocardial perfusion imaging: Lessons learned and work to be done—update

As the second term of our commitment to Journal begins, we, the editors, would like to reflect on a few topics that have relevance today. These include prognostication and paradigm shifts; Serial testing: How to handle data? Is the change in perfusion predictive of outcome and which one? Ischemia-guided therapy: fractional flow reserve vs perfusion vs myocardial blood flow; positron emission tomography (PET) imaging using Rubidium-82 vs N-13 ammonia vs F-18 Flurpiridaz; How to differentiate microvascular disease from 3-vessel disease by PET? The imaging scene outside the United States, what are the differences and similarities? Radiation exposure; Special issues with the new cameras? Is attenuation correction needed? Are there normal databases and are these specific to each camera system? And finally, hybrid imaging with single-photon emission tomography or PET combined with computed tomography angiography or coronary calcium score. We hope these topics are of interest to our readers.

Left Ventricular Dyssynchrony Assessment Using Myocardial Single-Photon Emission CT

Myocardial SPECT using standard procedure for perfusion imaging and phase analysis is a novel approach to left ventricular dyssynchrony assessment. Preliminary data suggest excellent repeatability and potential utility for guiding cardiac resynchronization therapy and elucidating mechanisms.

Inotropic stress with arbutamine is superior to vasodilator stress with dipyridamole for the detection of reversible ischemia with Tc-99m sestamibi single-photon emission computed tomography

BackgroundThere is a paucity of data comparing the relative merits of inotropic and vasodilator stress Tc-99m sestamibi single-photon emission computed tomography (SPECT) for the detection of coronary artery disease and reversible ischemia.Methods and ResultsTwenty-seven patients referred for diagnostic coronary arteriography underwent separate day dipyridamole and arbutamine Tc-99m sestamibi SPECT imaging with simultaneous two-dimensional echocardiography. The sensitivity of arbutamine and dipyridamole Tc-99m sestamibi for the detection of coronary artery disease was 100% (21 of 21) and 90% (19 of 21), respectively, with a specificity of 66% (4 of 6) for both. Coronary artery disease was detected in all six patients with single vessel disease by both stress modalities. The sensitivity for prediction of multivessel disease was 66% (10 of 15) for arbutamine and 46% (7 of 15) for dipyridamole stress. Arbutamine stress induced a greater extent and severity of perfusion abnormality at peak stress (peak perfusion score 25±6.2 and 21±5.9 for arbutamine and dipyridamole, respectively, p=0.001) and reversible perfusion defects (difference between peak stress and rest scores 8.8±5.5 and 5.2±4.4 for arbutamine and dipyridamole, respectively, p=0.001). Furthermore a significantly higher percentage of reversible defects induced by arbutamine stress was associated with wall thickening abnormality on simultaneous echocardiography, which is a more specific marker of myocardial ischemia (88% and 24% for arbutamine and dipyridamole, respectively, p=0.002).ConclusionInotropic stress may be superior to vasodilators for the determination of the extent and severity of myocardial involvement and reversible ischemia by Tc-99m sestamibi SPECT.