Performance of cardiac PET/CT with and without phase analysis for detection of scar in cardiac sarcoidosis: Comparison to cardiac magnetic resonance imaging

BACKGROUND

The presence of myocardial scar in CS patients results in poor prognosis and worse outcomes. 18F-fluorodeoxyglucose (18F-FDG) PET/CT excels at visualizing inflammation but is suboptimal at detecting scar. We evaluated PET/CT sensitivity to detect scar and investigated the incremental diagnostic value of automated PET-derived data.

METHODS

176 patients who underwent cardiac magnetic resonance (CMR) and N-13 ammonia/18F-FDG cardiac PET/CT for suspected CS within 3 months were enrolled. Scar was defined as late gadolinium enhancement (LGE) on CMR without concordant 18F-FDG uptake on 18F-FDG PET/CT. Accuracy of cardiac PET/CT at detecting scar (perfusion defect without concordant 18F-FDG uptake) was assessed before and after addition of automated PET-derived data.

RESULTS

Sensitivity of PET/CT for scar detection was 45.3% (specificity 88.9%). Addition of PET-derived LV volumes and function in a logistic regression model improved sensitivity to 57.0% (specificity: 80.0%, AUC 0.72). Addition of phase analysis maximum segmental onset of myocardial contraction > 61 improved AUC to 0.75, correctly relabeling 16.3% of patients as scar (net reclassification index 8.2%).

CONCLUSION

Sensitivity of gated PET MPI alone for scar detection in CS is suboptimal. Adding PET-derived volumes/function and phase analysis data results in improved detection and characterization of scar.

An under-recognized phenomenon: Myocardial volume change during the cardiac cycle

BACKGROUND

Myocardial volume is assumed to be constant over the cardiac cycle in the echocardiographic models used by professional guidelines, despite evidence that suggests otherwise. The aim of this paper is to use literature-derived myocardial strain values from healthy patients to determine if myocardial volume changes during the cardiac cycle.

METHODS

A systematic review for studies with longitudinal, radial, and circumferential strain from echocardiography in healthy volunteers ultimately yielded 16 studies, corresponding to 2917 patients. Myocardial volume in systole (MVs) and diastole (MVd) was used to calculate MVs/MVd for each study by applying this published strain data to three models: the standard ellipsoid geometric model, a thin-apex geometric model, and a strain-volume ratio.

RESULTS

MVs/MVd<1 in 14 of the 16 studies, when computed using these three models. A sensitivity analysis of the two geometric models was performed by varying the dimensions of the ellipsoid and calculating MVs/MVd. This demonstrated little variability in MVs/MVd, suggesting that strain values were the primary determinant of MVs/MVd rather than the geometric model used. Another sensitivity analysis using the 97.5th percentile of each orthogonal strain demonstrated that even with extreme values, in the largest two studies of healthy populations, the calculated MVs/MVd was <1.

CONCLUSIONS

Healthy human myocardium appears to decrease in volume during systole. This is seen in MRI studies and is clinically relevant, but this study demonstrates that this characteristic was also present but unrecognized in the existing echocardiography literature.

Myocardial Ischemia in the Management of Chronic Coronary Artery Disease: Past and Present

For many years, stress-induced myocardial ischemia has been considered important in the management of chronic coronary artery disease. Early evidence focused on the exercise ECG and the Duke treadmill score. In the 1970s, randomized clinical trials, which compared coronary artery bypass surgery to medical therapy, enrolled patients who were very different from contemporary practice and had inconsistent results. Surgery appeared to be of greatest benefit in high-risk patients defined by anatomy (such as left main disease) or stress-induced ischemia. However, randomized clinical trials of revascularization versus contemporary medical therapy over the past 20 years have been surprisingly negative. Nuclear cardiology substudies from these trials reported inconsistent results. Two observational studies from a single-center provided the best evidence for the use of stress-induced ischemia to identify patients who were most likely to benefit from revascularization. The recently completed ISCHEMIA trial (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches) was designed to test the hypothesis that revascularization would improve outcomes in patients with moderate-severe ischemia on stress testing. Unfortunately, 14.2% of the randomized patients had either mild or no ischemia on core lab review. Nearly one-quarter of the patients were randomized on the basis of an exercise ECG without imaging. The negative results of the trial reflect the long-term population decline in coronary artery disease and abnormal stress tests, as well as improvements in patient outcome due to optimal medical therapy. Topics requiring further research are presented. The implications of the trial for the use of both stress imaging and coronary computed tomography angiography in clinical practice are examined.

Cardiac MRI demonstrates compressibility in healthy myocardium but not in myocardium with reduced ejection fraction

BACKGROUND

The professional guidelines assume that the myocardial volume in systole (MVs) is equal to that in diastole (MVd), despite some limited evidence that points to the contrary. The aim of this manuscript is to determine whether this is true in healthy myocardium using gold standard cardiac MRI, as well as transthoracic echocardiography (TTE). The secondary aim is to determine whether there are similar MV changes in patients with heart failure with reduced ejection fraction (HFrEF).

METHOD

A prospectively derived cohort at Mayo Clinic of 115 adult subjects (mean age 42.8 years, 58% female) with no cardiac risk factors was identified. Cardiac MRI was obtained on all 115 patients, 51 of whom also consented to a TTE. MRI from a retrospectively derived cohort of 50 HFrEF patients was also collected. MVs and MVd was calculated using standard approaches with inclusion of the papillary muscles.

RESULTS

In the healthy population, MRI demonstrated MVs/MVd = 0.87 (SD 0.04) and TTE demonstrated MVs/MVd = 0.79 (SD 0.07), suggesting compressibility (p < 0.0001). In the 51 healthy patients who received both imaging modalities, MVs/MVd was 8.0% higher in MRI than TTE (p < 0.0001), but both modalities had MVs/MVd < 1 (p < 0.0001). A Bland-Altman plot demonstrated that as the mean MVs/MVd increases, the difference in MVs/MVd MRI-TTE declines (r = -0.53, p < 0.0001). However, in HFrEF populations, MVs/MVd = 1.01 (0.03), suggesting myocardial incompressibility.

CONCLUSION

Contrary to currently accepted standards, healthy myocardium is compressible but HFrEF myocardium is incompressible. The ratio MVs/MVd merits further study in an expanded normal cohort and in disease states.

Systolic-to-diastolic myocardial volume ratio as a novel imaging marker of cardiomyopathy

BACKGROUND

In patients with normal left ventricular ejection fraction, it may be difficult to distinguish between the normal and diseased heart. Novel assessments of ventricular function, such as extracellular volume imaging, myocardial perfusion imaging and myocardial contraction fraction are emerging to better assess disease burden in these cases. This study endeavored to determine whether the ratio of myocardial volume in systole to myocardial volume in diastole (MVs/MVd), differs between normal hearts and those with disease states characterized by normal ejection fraction.

METHOD

Consecutive patients from 2008 to 2018 with hypertrophic cardiomyopathy (HCM), cardiac amyloidosis, and heart failure with preserved ejection fraction (HFpEF) who underwent cardiac magnetic resonance imaging (MRI) were selected for inclusion, along with a sex- and age-matched cohort of normal volunteers who also underwent cardiac MRI. Manual tracings were performed on each MRI to calculate MVs/MVd, which was then compared across subgroups.

RESULTS

Included were 50 patients with HCM, 50 patients with cardiac amyloidosis, 26 patients with HFpEF, and 30 normal subjects. Age was 54.1 years (SD 16.7); mean MVs/MVd was 0.88 (SD 0.04) in the normal subgroup, 1.03 (SD 0.06) in HCM patients, 1.03 (SD 0.06) in cardiac amyloidosis patients, and 0.97 (SD 0.02) in HFpEF patients, with all pathology subgroups different from the normal subgroup (p < .0001 for each). The ratio of MVs/MVd discriminated diseased from normal with c statistic 0.989 (p < .001).

CONCLUSIONS

This study suggests that a novel and easily-captured metric of ventricular function, MVs/MVd, can differentiate normal ventricular function from multiple cardiomyopathies with normal ejection fractions.

Coronary Disease Surveillance in the Community: Angiography and Revascularization

Background Temporal declines in cardiac stress tests results, coronary revascularization, and cardiovascular mortality have suggested a decline in the population burden of coronary disease until the 2000s. However, recent data indicate these favorable trends could be ending. We aimed to assess the evolution of the population burden of coronary disease in the community by examining trends in angiography and revascularization. Methods and Results We analyzed age- and sex-adjusted trends from all coronary angiographic diagnostic procedures and revascularizations performed in Olmsted County, MN from 2000 to 2018. A total of 12 981 invasive angiograms were performed among 9049 individuals (64% men; 55% aged ≥65 years). Adjusted angiography rates decreased by 30% (95% CI, 25%-34%) between 2000 and 2009 and leveled off thereafter. Including computed tomography, angiography uncovered an increase in angiography use in recent years (risk ratio=1.15 [95% CI, 1.07-1.23] for 2018 versus 2014) and a decline in the prevalence of anatomic CAD from 2000 to 2018. CAD severity declined substantially from 2000 to 2009, followed by a plateau. Among 6570 revascularizations (72% men; 57% aged ≥65 years), 77% were percutaneous coronary interventions and 23% coronary artery bypass graft surgeries. The adjusted revascularization rates declined by 34% (95% CI, 27%-39%) from 2000 to 2009, followed by a plateau (risk ratio=1.10 [95% CI, 1.00-1.22]). Conclusions Between 2000 and 2018 in the community, coronary angiography use declined initially, leveled off, and then increased. Trends in CAD severity and revascularization use decreased then plateaued. The most recent trends are concerning as they suggest the burden of coronary disease is no longer declining. This warrants reinvigorated primary prevention and population surveillance.

Stress Testing in the Evaluation of Stable Chest Pain in a Community Population

OBJECTIVE

To evaluate the use of stress testing in a community population with de novo stable chest pain, a normal resting electrocardiogram (ECG), and the ability to exercise.

PATIENTS AND METHODS

We identified eligible patients by searching the electronic medical record of all outpatients seen at Mayo Clinic Rochester from January 1, 2010, through December 31, 2013. We determined the frequency of initial exercise stress testing, computed tomography coronary angiography, and invasive coronary angiography, as well as the use of subsequent second procedures (including percutaneous coronary intervention [PCI] and coronary artery bypass grafting) within 90 days. Patients were followed for 5 years for death, nonfatal myocardial infarction, and hospitalization for unstable angina.

RESULTS

The data search identified 1175 patients with chest pain and normal resting ECGs. Only 331 patients underwent cardiac testing. A slight majority (185; 55.9%) underwent an exercise ECG alone. The remainder underwent exercise echocardiography (112; 33.8%), exercise single-photon-emission computed tomography (32; 9.7%), or computed tomography coronary angiography (2; 0.9%). Few patients (30; 9.1%) required additional testing within 90 days. Of the 14 patients (4.2%) who underwent invasive coronary angiography, 12 (85.7%) had significant coronary artery disease, and were referred for percutaneous coronary intervention or coronary artery bypass grafting. At 5 years, the mortality rate was 1.2%, and the combined event rate was 3.8%.

CONCLUSION

Most community patients with chest pain and a normal resting ECG do not require further cardiac evaluation. In patients who require testing, and are able to exercise, noninvasive stress testing is preferred. Invasive coronary angiography is applied selectively and associated with a high rate of significant coronary artery disease and referral to coronary revascularization. Long-term outcomes are excellent.

Phase analysis single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) detects dyssynchrony in myocardial scar and increases specificity of MPI

BACKGROUND

Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is commonly used to assess patients with cardiovascular disease. However, in certain scenarios, it may have limited specificity in the identification of hemodynamically significant coronary artery disease (e.g., false positive), potentially resulting in additional unnecessary testing and treatment. Phase analysis (PA) is an emerging, highly reproducible quantitative technology that can differentiate normal myocardial activation (synchrony) from myocardial scar (dyssynchrony). The objective of this study is to determine if PA can improve the specificity SPECT MPI.

METHODS

An initial cohort of 340 patients (derivation cohort), referred for SPECT-MPI, was prospectively enrolled. Resting MPI studies were assessed for resting perfusion defects (scar). These were utilized as the reference standard for scar. Subsequently, we collected a second independent validation cohort of 138 patients and tested the potential of PA to reclassify patients for the diagnosis of "scar" or "no scar." Patients were assigned to three categories depending upon their pre-test probability of scar based on multiple clinical and imaging parameters: ≤ 10% (no scar), 11-74% (indeterminate), and ≥ 75% (scar). The ability of PA variables to reclassify patients with scar to a higher group and those without scar to a lower group was then determined using the net reclassification index (NRI).

RESULTS

Entropy (≥ 59%) was independently associated with scar in both patient cohorts with an odds ratio greater than five. Furthermore, when added to multiple clinical/imaging variables, the use of entropy significantly improved the area under the curve for assessment of scar (0.67 vs. 0.59, p = 0.04). The use of entropy correctly reclassified 24% of patients without scar, by clinical model, to a lower risk category (as determined by pre-test probability) with an overall NRI of 18% in this validation cohort.

DISCUSSION

The use of PA entropy can improve the specificity of SPECT MPI and may serve as a useful adjunctive tool to the interpreting physician. The current study determined the optimal PA parameters to detect scar (derivation cohort) and applied these parameters to a second, independent, patient group and noted that entropy (≥ 59%) was independently associated with scar in both patient cohorts. Therefore, PA, which requires no additional imaging time or radiation, enhances the diagnostic capabilities of SPECT MPI.

CONCLUSION

The use of PA entropy significantly improved the specificity of SPECT MPI and could influence the labeling of a patient as having or not having myocardial scar and thereby may influence not only diagnostic reporting but also potentially prognostic determination and therapeutic decision-making.

Moving from volume to value for revascularization in stable ischemic heart disease: A review

IMPORTANCE

Although percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are both commonly employed in the treatment of stable ischemic heart disease (SIHD), their ability to reduce subsequent heart attacks and death is currently in question. These procedures will come under increasing scrutiny as the healthcare reimbursement system moves away from the traditional fee for service model in favor of "pay for value".

OBSERVATION

Both international and domestic data show wide variability in the use of PCI and CABG in patients with SIHD. There is evidence of ongoing quality improvement over the last 5 years in reducing the use of inappropriate procedures, but there is still room for improvement. We present ideas regarding health policy interventions that might help manage the transition to value-based payments in this area, including improvements in national registries, more rapid revision of appropriate use criteria, shared decision making, and evidence-based management of PCI in SIHD.

CONCLUSIONS AND RELEVANCE

The use of revascularization procedures in patients with SIHD is potentially a model for how care might be improved with health care policy intervention. We suggest that the status quo, although apparently improved over the last 5 years, is still unacceptable when 25% of hospitals have a rate of unnecessary PCI in patients with SIHD that approaches 25%.

Use of echocardiography in outpatients with chest pain and normal resting electrocardiograms referred to Mayo Clinic Rochester

OBJECTIVES

To determine how often unnecessary resting echocardiograms that are "not recommended" by clinical practice guidelines are performed in patients with stable chest pain and normal resting electrocardiograms (ECGs).

BACKGROUND

There are scant data to indicate how often Class III recommendations are ignored in clinical practice.

PATIENTS AND METHODS

We searched electronically all medical records of referral outpatients seen at Mayo Clinic Rochester from January 1, 2010, through December 31, 2013, to identify patients with stable chest pain and known or suspected coronary artery disease who underwent resting echocardiography and had normal resting ECGs and no other indication for echocardiography.

RESULTS

Of the 15,529 referral outpatients who were evaluated at Mayo Clinic Rochester with chest pain, 3976 (25.6%) had resting echocardiograms. Eight hundred seventy of these 3976 patients (21.9%) had normal resting ECGs. Six hundred nineteen of these 870 patients (71.1%) had other indications for echocardiography. The remaining 251 patients (6.3% of all echocardiograms and 1.6% of all patients) had normal resting ECGs and no other indication for echocardiography. Two hundred thirty-nine of these 251 patients (95.2%) had normal echocardiograms. Of the 12 abnormal echocardiograms, only 4 led to any change in clinical management. Sixty-one of these 251 echocardiograms (24.3%) were "preordered" before the provider (physicians, nurses, physician assistants) visit.

CONCLUSION

Echocardiograms were performed in 1 in 4 referral outpatients with chest pain seen at Mayo Clinic Rochester. However, only 1 in 16 of these echocardiograms was performed in violation of the class III recommendation in the American College of Cardiology Foundation/American Heart Association guidelines for the management of stable angina. These unnecessary echocardiograms were almost always normal, and had little impact on clinical management. The rate of unnecessary echocardiograms could be decreased by eliminating preordering.

Temporal Trends of Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging in Patients With Coronary Artery Disease

Background—

There has been a gradual decline in the prevalence of abnormal stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging studies among patients without history of coronary artery disease (CAD). The trends of SPECT studies among patients with known CAD have not been evaluated previously.

Methods and Results—

We assessed the Mayo Clinic nuclear cardiology database for all stress SPECT tests performed between January 1991 and December 2012 in patients with history of CAD defined as having previous myocardial infarction, percutaneous coronary intervention, and coronary artery bypass grafting. The study cohort was divided into 5 time periods: 1991 to 1995, 1996 to 2000, 2001 to 2005, 2006 to 2010, and 2011 to 2012. There were 19 373 patients with a history of CAD who underwent SPECT between 1991 and 2012 (mean age, 66.2±10.9 years; 75.4% men). Annual utilization of SPECT in these patients increased from an average of 495 tests per year in 1991 to 1995 to 1425 in 2003 and then decreased to 552 tests in 2012 without evidence for substitution with other stress modalities. Asymptomatic patients initially increased until 2006 and then decreased. Patients with typical angina decreased, whereas patients with dyspnea and atypical angina increased. High-risk SPECT tests significantly decreased, and the percentage of low-risk SPECT tests increased despite decreased SPECT utilization between 2003 and 2012. Almost 80% of all tests performed in 2012 had a low-risk summed stress score compared with 29% in 1991 ( P <0.001).

Conclusions—

In Mayo Clinic, Rochester, annual SPECT utilization in patients with previous CAD increased between 1992 and 2003, but then decreased after 2003. High-risk SPECT tests declined, whereas low-risk tests increased markedly. Our results suggest that among patients with a history of CAD, SPECT was being increasingly utilized in patients with milder CAD. This trend parallels reduced utilization of other stress modalities, coronary angiography, reduced smoking, and greater utilization of optimal medical therapy for prevention and treatment of CAD.

Use of Echocardiography in Olmsted County Outpatients With Chest Pain and Normal Resting Electrocardiograms Seen at Mayo Clinic Rochester

OBJECTIVE

To determine how often unnecessary resting echocardiograms that are "not recommended" by clinical practice guidelines are performed in patients with stable chest pain and normal resting electrocardiograms (ECGs).

PATIENTS AND METHODS

We performed a retrospective search of electronic medical records of all outpatients seen at Mayo Clinic Rochester from January 1, 2010, through December 31, 2013, to identify residents of Olmsted County, Minnesota, with stable chest pain and known or suspected coronary artery disease who underwent resting echocardiography and had normal resting ECGs and no other indication for echocardiography.

RESULTS

Of the 8280 outpatients from Olmsted County who were evaluated at Mayo Clinic Rochester with chest pain, 590 (7.1%) had resting echocardiograms. Ninety-two of these 590 patients (15.6%) had normal resting ECGs. Thirty-three of these 92 patients (35.9%) had other indications for echocardiography. The remaining 59 patients (10.0% of all echocardiograms and 0.7% of all patients) had normal resting ECGs and no other indication for echocardiography. Fifty-seven of these 59 patients (96.6%) had normal echocardiograms. Thirteen of these 59 echocardiograms (22.0%) were "preordered" before the provider (physicians, nurses, physician assistants) visit.

CONCLUSION

The overall rate of echocardiography in Olmsted County outpatients with chest pain seen at Mayo Clinic Rochester is low. Only 1 in 10 of these echocardiograms was performed in violation of the class III recommendation in the American College of Cardiology Foundation/American Heart Association guidelines for the management of stable angina. These unnecessary echocardiograms were almost always normal. The rate of unnecessary echocardiograms could be decreased by eliminating preordering.

Beliefs and attitudes towards mental illness: an examination of the sex differences in mental health literacy in a community sample

Objectives. The current study investigated mental health literacy in an Australian sample to examine sex differences in the identification of and attitudes towards various aspects of mental illness. Method. An online questionnaire was completed by 373 participants (M = 34.87 years). Participants were randomly assigned either a male or female version of a vignette depicting an individual exhibiting the symptoms of one of three types of mental illness (depression, anxiety, or psychosis) and asked to answer questions relating to aspects of mental health literacy. Results. Males exhibited poorer mental health literacy skills compared to females. Males were less likely to correctly identify the type of mental illness, more likely to rate symptoms as less serious, to perceive the individual as having greater personal control over such symptoms, and less likely to endorse the need for treatment for anxiety or psychosis. Conclusion. Generally, the sample was relatively proficient at correctly identifying mental illness but overall males displayed poorer mental health literacy skills than females.

Implications of ventricular arrhythmia “bursts” with normal epicardial flow, myocardial blush, and ST-segment recovery in anterior ST-elevation myocardial infarction reperfusion: A biosignature of direct myocellular injury “downstream of downstream”

Aims:

Establishing epicardial flow with percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is necessary but not sufficient to ensure nutritive myocardial reperfusion. We evaluated whether adding myocardial blush grade (MBG) and quantitative reperfusion ventricular arrhythmia “bursts” (VABs) surrogates provide a more informative biosignature of optimal reperfusion in patients with Thrombolysis in Myocardial Infarction (TIMI) 3 flow and ST-segment recovery (STR).

Methods and results:

Anterior STEMI patients with final TIMI 3 flow had protocol-blinded analyses of simultaneous MBG, continuous 12-lead electrocardiogram (ECG) STR, Holter VABs, and day 5–14 SPECT imaging infarct size (IS) assessments. Over 20 million cardiac cycles from >4500 h of continuous ECG monitoring in subjects with STR were obtained. IS and clinical outcomes were examined in patients stratified by MBG and VABs. VABs occurred in 51% (79/154) of subjects. Microcirculation (MBG 2/3) was restored in 75% (115/154) of subjects, of whom 53% (61/115) had VABs. No VABs were observed in subjects without microvascular flow (MBG of 0). Of 115 patients with TIMI 3 flow, STR, and MBG 2/3, those with VABs had significantly larger IS (median: 23.0% vs 6.0%, p=0.001). Multivariable analysis identified reperfusion VABs as a factor significantly associated with larger IS ( p=0.015).

Conclusions:

Despite restoration of normal epicardial flow, open microcirculation, and STR, concomitant VABs are associated with larger myocardial IS, possibly reflecting myocellular injury in reperfusion settings. Combining angiographic and ECG parameters of epicardial, microvascular, and cellular response to STEMI intervention provides a more predictive “biosignature” of optimal reperfusion than do single surrogate markers.

Abstract 212: Temporal Trends of SPECT Myocardial Perfusion Imaging in Patients with Coronary Heart Disease: A 22-Year Experience from a Tertiary Academic Medical Center

Background: Over the past 20 years, there has been an increasing decline in the prevalence of abnormal stress single-photon emission computed tomography myocardial perfusion imaging (SPECT) studies among patients with no history of coronary artery disease (CAD). The trend of SPECT studies among patients with known CAD has not been evaluated before.

Methods: Using the Mayo Clinic nuclear cardiology database, we examined all stress SPECT tests performed between 1/1991-12/2012 in patients with prior history of CAD defined as having prior myocardial infarction, percutaneous coronary intervention, and/or coronary artery bypass grafting. Patients with left bundle branch block, paced rhythm, bicycle or rest-only tests, cardiomyopathy, valvular heart disease, and technically unsatisfactory studies were excluded. The study cohort was divided into 5 time periods: 1991-5, 1996-2000, 2001-5, 2006-10, and 2011-12.

Results: There were 19373 eligible SPECT tests (mean age 66.2 ± 10.9y, 75.4% men). Annual utilization of SPECT studies in patients with history of CAD increased from an average of 495 tests per year between 1991-1995 to a peak of 1425 in 2003; and then decreased to 552 tests in 2012. Asymptomatic patients comprised 33% in 1991-1995, peaked at 48% in 2006, and then decreased back to 31% in 2012. Over time, patients with typical angina decreased while patients with dyspnea increased, P <0.001 (Fig 1). The percentage of high risk SPECT tests significantly decreased, and the percentage of low-risk SPECT tests significantly increased despite the overall decline of SPECT utilization between 2003 and 2012. Almost 80% of all tests performed in 2012 had a low risk summed stress score compared to 29% in 1991, P <0.001 (Fig 2).

Conclusions: In Mayo Clinic Rochester, annual SPECT utilization in patients with prior CAD increased between 1992 and 2003, but then decreased significantly after 2003. Fewer patients had typical angina while patients with dyspnea increased over time. High risk SPECT tests declined while low risk tests increased dramatically. These data suggest that stress SPECT was being increasingly utilized in CAD patients without typical angina who are at low risk.

Patient-centered imaging: shared decision making for cardiac imaging procedures with exposure to ionizing radiation

The current paper details the recommendations arising from an NIH-NHLBI/NCI-sponsored symposium held in November 2012, aiming to identify key components of a radiation accountability framework fostering patient-centered imaging and shared decision-making in cardiac imaging. Symposium participants, working in 3 tracks, identified key components of a framework to target critical radiation safety issues for the patient, the laboratory, and the larger population of patients with known or suspected cardiovascular disease. The use of ionizing radiation during an imaging procedure should be disclosed to all patients by the ordering provider at the time of ordering, and reinforced by the performing provider team. An imaging protocol with effective dose ≤3 mSv is considered very low risk, not warranting extensive discussion or written informed consent. However, a protocol effective dose >20 mSv was proposed as a level requiring particular attention in terms of shared decision-making and either formal discussion or written informed consent. Laboratory reporting of radiation dosimetry is a critical component of creating a quality laboratory fostering a patient-centered environment with transparent procedural methodology. Efforts should be directed to avoiding testing involving radiation, in patients with inappropriate indications. Standardized reporting and diagnostic reference levels for computed tomography and nuclear cardiology are important for the goal of public reporting of laboratory radiation dose levels in conjunction with diagnostic performance. The development of cardiac imaging technologies revolutionized cardiology practice by allowing routine, noninvasive assessment of myocardial perfusion and anatomy. It is now incumbent upon the imaging community to create an accountability framework to safely drive appropriate imaging utilization.

Downstream clinical implications of abnormal myocardial perfusion single-photon emission computed tomography based on appropriate use criteria

BACKGROUND

Appropriate use criteria (AUC) for single-photon emission computed tomography myocardial perfusion images (SPECT-MPI) were developed to address the growth of cardiac imaging studies. However, these criteria have not been vigorously validated. We sought to determine the rate of abnormal stress SPECT-MPI studies and subsequent revascularization procedures as categorized by AUC.

METHODS

We retrospectively examined 280 patients who underwent stress SPECT-MPI and categorized these studies as appropriate, inappropriate, or uncertain based on AUC. Data regarding subsequent angiography and revascularization within 6 months after stress SPECT-MPI were collected from the electronic medical record.

RESULTS

280 patients met the inclusion criteria (mean age 67.3 ± 11.4 years, 36 % female). When categorized by AUC, 62.9 % (N = 176) of stress SPECT-MPI were considered appropriate, 13.6 % (N = 38) uncertain, and 23.6 % (N = 66) inappropriate. Appropriate stress SPECT-MPI studies were more likely to have intermediate or high risk results than uncertain or inappropriate studies [40 % (N = 71) vs. 21 % (N = 8) and 18 % (N = 12), respectively; P = 0.008)]. Appropriate studies were associated with an increased rate of coronary angiography [14 % (N = 25)] compared to the uncertain (0 %) and inappropriate [3 % (N = 2)] studies (P = 0.003). There was also an increased rate of revascularization after appropriate studies [9 % (N = 16)] compared to the uncertain (0 %) and inappropriate (0 %) studies (P = 0.006).

CONCLUSIONS

Appropriate stress SPECT-MPI studies are more likely to result in abnormal results requiring subsequent revascularization compared to inappropriate and uncertain stress studies. Inappropriate and uncertain stress SPECT-MPI did not lead to subsequent revascularization.

Abstract 40: Temporal Trends of SPECT Myocardial Perfusion Imaging in Patients without Coronary Artery Disease: A 17-Year Experience from a Tertiary Academic Medical Center

Background: Between 1990-2006, there was a tremendous increase in utilization of single photon emission computed tomography myocardial perfusion imaging (SPECT). Characteristics of the observed increase of SPECT utilization have never been studied.

Methods: Using the Mayo Clinic nuclear cardiology database, we examined all SPECT tests performed between 1/1/1991-12/31/2007 in patients without prior coronary artery disease (CAD). Patients with history of CAD, left bundle branch block, paced rhythm, bicycle/ rest-only tests, cardiomyopathy, valvular heart disease, and technically unsatisfactory studies were excluded. The study cohort was divided into 4 time periods: 1991-5, 1996-2000, 2001-5, and 2006-7.

Results: There were 29255 eligible SPECT tests (mean age 62.4 ± 12y, 54% men). Annual utilization of SPECT studies increased from 682 in 1992 to a peak of 2738 in 2002, and then decreased to 2134 in 2007, Fig 1. There were very modest changes in CAD risk factors over time. Testing of asymptomatic patients nearly doubled (21.9% in 1991-5 to 42.7% in 2006-7). Tests on patients with typical angina decreased dramatically (18.3% in 1991-5 to 5.3% in 2006-7), Fig 2. Summed stress score, summed difference score, and high risk SPECT tests decreased over time, Fig 3. Normal SPECT studies and negative study ECG increased for both pharmacologic and exercise tests.

Conclusions: In Mayo Clinic Rochester, annual SPECT utilization in patients without prior CAD increased between 1992 and 2002, but then decreased in advance of national trends. Normal tests increased, while summed stress score, summed difference score, and high risk tests all decreased. These data suggest that SPECT was increasingly utilized in patients with a lower prevalence of CAD.

Population-based study of the use of cardiac stress imaging and referral for coronary angiography and repeated revascularization after coronary artery bypass graft surgery

OBJECTIVE

To assess stress single-photon emission computed tomography (SPECT) and stress echocardiography use after coronary artery bypass grafting (CABG) and their effect on referral for coronary angiography and revascularization.

PATIENTS AND METHODS

The referral, timing, and results of stress imaging after CABG; referral for coronary angiography and revascularization; and all-cause mortality were assessed in this longitudinal, population-based, retrospective study of 1138 Olmsted County, Minnesota, patients undergoing CABG between January 1, 1993, and December 31, 2003.

RESULTS

A total of 570 patients (50.1%) underwent a stress imaging study (341 SPECT and 229 echocardiography) during the study period. Of the 1138 patients, 372 (32.7%) were referred for coronary angiography, and 144 of those patients (12.7%) underwent repeated revascularization (132 percutaneous revascularization and 12 CABG). The median interval between CABG and the index stress imaging study was 3.0 years (25th-75th percentile, 1.2-5.7 years). The results of 75.7% (258 of 341) of the stress SPECT studies and 70.7% (162 of 229) of the stress echocardiograms were abnormal. Seventy-six of 570 patients (13.3%) referred for stress imaging underwent coronary angiography within 180 days after the stress test. Repeated coronary revascularization was performed in 25 patients (4.4%) who underwent a stress imaging study within the preceding 180 days. The 5- and 10-year survival rates in the entire study cohort (83.5% and 65.1%, respectively) were not significantly different than predicted for the age- and sex-matched Minnesota population.

CONCLUSION

Half of this community-based population of patients with CABG underwent stress SPECT or echocardiography during median follow-up of 8.9 years. Despite that approximately 75% of the results of stress imaging studies were abnormal, subsequent referral for coronary angiography within 180 days was low (13.3%), and the yield for repeated revascularization was very low (4.4%).

Impact of left ventricular function and the extent of ischemia and scar by stress myocardial perfusion imaging on prognosis and therapeutic risk reduction in diabetic patients with coronary artery disease: results from the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial

BACKGROUND

The Bypass Angioplasty Revascularization Investigation 2 Diabetes trial demonstrated similar long-term clinical effectiveness of revascularization (REV) and intensive medical (MED) therapy. Comparisons of post-intervention ischemic burden have not been explored but are relevant to treatment decisions. This study examined differences in 1-year stress myocardial perfusion SPECT (MPS) abnormalities by randomized treatment.

METHODS

MPS was performed in 1,505 patients at 1-year following randomization. MPS images were analyzed (masked to treatment) by a Nuclear Core Laboratory using a quantitative percent (%) of total, ischemic, and scarred myocardium. Cox proportional hazards models were used to estimate the relationship between MPS variables and trial endpoints.

RESULTS

At 1-year, nearly all REV patients underwent the assigned procedure; while 16% of those randomized to MED received coronary REV. Patients randomized to REV exhibited fewer stress perfusion abnormalities than MED patients (P < .001). CABG patients had more frequent ischemic and scarred myocardium encumbering ≥ 5% of the myocardium when compared to those receiving PCI. Patients randomized to MED had more extensive ischemia and the median % of the myocardium with perfusion abnormalities was lower following REV (3% vs 9%, P = .01). A total of 59% of REV patients had no inducible ischemia at 1-year compared to 49% of MED patients (P < .001). Within the CABG stratum, those randomized to MED had the greatest rate of ischemic (P = .032) and scarred (P = .017) perfusion abnormalities. At 1-year, more extensive and severe stress myocardial perfusion abnormalities were associated with higher 5-year rates of death and a combined endpoint of cardiac death or myocardial infarction (MI) rates (11.3%, 8.1%, 6.8%, for ≥ 10%, 5%-9.9%, and 1-4.9% abnormal myocardium at stress, respectively, P < .001). In adjusted models, selected MPS variables were significantly associated with an increased hazard of cardiac death or MI (hazard ratio = 1.11 per 5% increase in abnormal myocardium at stress, P = .004).

CONCLUSIONS

Patient management strategies that focus on ischemia resolution can be useful to guide the efficacy of near-term therapeutic approaches. A 1-year post-therapeutic intervention myocardial perfusion scan provides important information regarding prognosis in stable CAD patients with diabetes.