Gibbons, Raymond J.

We examined the value of thallium‐201 myocardial perfusion scintigraphy in noninvasive assessment of cardiac risk in 36 insulin‐dependent (type 1) diabetic patients being evaluated for pancreas or combined pancreas/kidney transplantation. An extensive cardiovascular evaluation including electrocardiogram was performed in all patients, and most patients were also evaluated by two‐dimensional and Doppler echocardiography. Exercise thallium studies were performed in 31 patients. Five patients were unable to exercise and underwent dipyridamole‐thallium study. The thallium images were abnormal in 12 patients, 10 of whom underwent coronary arteriography. Significant coronary artery disease was found in 7 of these patients. Nineteen patients underwent pancreatic (3 patients) or pancreato‐renal (16) transplantation without any occurrence of cardiac death or nonfatal myocardial infarction peri‐operatively or on follow‐up ranging from 7 months to 21 months. In contrast, 3 cardiac events occurred in 12 patients not approved for transplantation, each of whom had an abnormal thallium study exhibiting significant ischemia. Resting left ventricular global and regional function was not helpful in determining perioperative risk. Thus, thallium‐201 myocardial perfusion scintigraphy may be useful in identifying diabetic patients at low risk for pancreas transplantation and may obviate the need for routine coronary angiography in these patients.

Purpose: We previously analyzed the 2006 appropriateness criteria for cardiac computed tomography (CT) and found 42% of our patients were not classifiable, suggesting the criteria were difficult to apply clinically. These criteria were revised in 2010. The purpose of our study is to compare the new 2010 appropriate use criteria to the original 2006 criteria to determine if the 2010 criteria were more applicable. Materials and Methods: In a previous study we applied the 2006 appropriateness criteria to 251 patients that underwent cardiac CT from June 1 to December 31, 2007. Each patient was assigned an indication from the 2006 appropriate use criteria by two observers, classifying patients as appropriate, inappropriate, uncertain, or nonclassifiable. A third observer settled disagreements. This process was applied to the same 251 patients using the 2010 criteria. The data from the previous study using the 2006 criteria was compared to the data obtained using the 2010 criteria to determine changes in the number of nonclassifiable, appropriate, inappropriate, and uncertain exams. These results were then analyzed using Bowker's test of symmetry. Observer agreement was calculated using the kappa statistic. Results: 115 patients (46%) were not classifiable using the 2006 criteria. When the 2010 criteria were applied, the number of not classifiable patients decreased to 40 (16%), with the plurality, 41 (16%), of the not classifiable patients moving to inappropriate. In 2006, 69 (27%) were classified as appropriate, 25 (10%) were uncertain, 42 (17%) inappropriate. In 2010, the appropriate increased to 84 (33%), uncertain increased to 40 (16%), and inappropriate increased to 87 (35%). Bowker's test of symmetry demonstrated a statistically significant change with a p<0.001. Agreement between the two observers assigning patients to classification groups also improved with a kappa of 0.55 using the 2010 criteria compared to kappa of 0.31 in 2006. Conclusion: The number of not classifiable patients decreased using the 2010 criteria and the interobserver agreement improved, suggesting they are more applicable and complete than the 2006 criteria. This decrease in not classifiable patients came primarily from an increase in the number of inappropriate indications.

The Impact of Ordering Provider Specialty on Appropriateness Classification In prior studies, our laboratory applied the ACCF/ASNC AUC for SPECT MPI to several cohorts of patients in Mayo Clinic Rochester. The purpose of this study was to re-examine our data to test the hypothesis that the specialty of the ordering provider affected the appropriateness. We compared the ordering providers specialty with appropriateness determined in prior studies. The study group consisted of 281 patients who underwent stress SPECT MPI studies in May 2005 and 282 patients in October 2006 (before any quality improvement initiatives were begun at Mayo). Appropriateness categories were assigned by 2 experienced nurses from the CV Research Studies Unit not affiliated with the nuclear laboratory. Patients who were studied for pre-operative evaluation (n = 20) or post myocardial infarction (n = 7) were excluded because they comprised less than 5 percent of the patients. Pre-operative testing in our institution is done primarily by stress echocardiography. The final study group consisted of 526 patients. Excluding the 64 unclassified patients, AUE categories were appropriate (75 %), uncertain (13 %), inappropriate (12%). Results by ordering provider are shown in the figure, where CV = Cardiovascular MDs, ED = Emergency Department MDs, IM = General and Internal Medicine MDs, RN = Registered Nurses, and SP = other Specialty MDs. There was no significant association (p = 0.19); Chi-square analysis between appropriateness and specialty groups. In a clinical practice where pre-operative testing using SPECT is infrequent, the rate of inappropriate studies was similar for all ordering providers. Quality improvement efforts in similar practices will likely require a broad focus on all ordering physicians/nurses.

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.

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.

Background : Unrecognized myocardial infarction (UMI), as diagnosed by surveillance electrocardiography (ECG), has the same poor prognosis as recognized (RMI), independent of ejection fraction or ischemia. The value of post UMI risk stratification by infarct size is unknown. Methods : The study group consisted of 5430 patients who underwent 2 day stress (exercise n = 191, pharmacologic n = 155) and rest Tc-99m sestamibi SPECT studies. UMI was diagnosed if ECG showed Q wave MI in the absence of history of MI. SPECT infarct size was quantitated based on a 60% of peak counts threshold method and was expressed as a percentage of the left ventricle (% LV). The association between infarct size and mortality was adjusted for clinical and exercise test prognostic scoring systems. Results : The population consisted of 346 UMI, 628 RMI, and 4456 patients without MI (No MI). Compared to No MI, mortality risk was increased in UMI (RR 1.7, 95% CI 1.6–1.9; p < 0.001) and RMI (RR 1.6, 95% CI 1.4–1.9; p < 0.001) patients. In the UMI group, infarct size was significantly associated with mortality ( p < 0.001), which persisted after adjustment for Mayo prognostic score alone (available in all patients) ( p < 0.001) and for Mayo prognostic score, Framingham risk score, and Duke treadmill score (data available in 137 patients) ( p < 0.001). For every 10% LV increase in infarct size, mortality risk increased 30% (RR = 1.3, 95% CI 1.2–1.5) (see figure ). Conclusions: In patients with UMI, larger quantitated SPECT infarct size predicts increased mortality independent of clinical and exercise test prognostic scoring systems. This finding supports the use of infarct size imaging for risk stratification of UMI patients.

Background— The Bypass Angioplasty Revascularization Investigation trial demonstrated that symptomatic diabetics with multivessel coronary artery disease had a survival advantage with initial coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI). No published study has examined different treatments and outcome in asymptomatic diabetics. Methods and Results— This study group consisted of 826 asymptomatic diabetics (age 62±12 years; 76% men) without known coronary artery disease who had abnormal myocardial perfusion during stress single photon emission computed tomography (SPECT). SPECT images were classified as low-, intermediate-, and high-risk. Early revascularization (CABG or PCI ≤4 months after SPECT) was performed in 76 patients. Survival (follow-up, 5.3±3.3 years) was compared in patients treated with CABG, PCI, or medical therapy. Revascularization (CABG or PCI) was performed in 54 of 261 patients with high-risk scans and was independently associated with improved survival (χ 2 =4.55; P =0.03 after multivariate adjustment). Subset analysis demonstrated that the survival advantage was confined to patients treated with CABG (n =39), with a 5-year survival CABG at 85%, PCI at 72%, and medical therapy at 67% ( P =0.02 for 3 groups). Although CABG was associated with better survival, mortality remained high (3% per year). There was no survival advantage by treatment for patients with less-severe SPECT abnormalities. Conclusions— These nonrandomized data suggest that CABG improves survival in asymptomatic diabetic patients with high-risk SPECT, although revascularization was performed infrequently in these patients. These results parallel those of the Bypass Angioplasty Revascularization Investigation trial in symptomatic diabetic patients.

Introduction: Cardiovascular disease remains the leading cause of morbidity and mortality in patients with amyloid light chain (AL) amyloidosis. Current prognostic evaluation in AL cardiomyopathy (AL-CM) largely relies upon disparate proxy measurements to assess mortality. With respect to observed myocardial volume changes between systole and diastole, we describe a single measurement derived from cardiac MRI (CMR) to assess mortality of AL-CM. Methods: A cohort of 129 consecutive patients with AL-CM undergoing CMR with amyloid protocol from the years 2001 - 1997 was reviewed. Myocardial volume change at end systole and end diastole was assessed by disc summation with CMR. The myocardial function index (MFI) was calculated by consolidating blood pool and myocardial volume measures as confluent components of myocardial function utilizing operator tracings. The association of MFI and death was assessed with adjusted hazard ratios (HR) derived by a Cox model. Results: Data at time of CMR was reviewed. The mean age was 60 ±10; 68% subjects were female. Median survival from CMR was 47 months. Mean LVEF was assessed by echocardiography to be 55% ± 12. Mean calculated MFI was 19.8% ±7. Univariate analysis suggested MFI is strongly associated with death (HR 0.004; 95%CI 0.00002-0.0838; p = 0.0003). A multivariate analysis re-demonstrated the strong predictive value of MFI when controlled for age (HR 0.006; 95%CI 0.00003 - 0.1156; p = 0.0006). Conclusion: MFI strongly correlates with mortality in AL-CM. In contrast to previously described assessments of ventricular function (extracellular volume imaging, myocardial perfusion imaging, and myocardial contraction fraction), MFI is easily derived from CMR and considers blood pool and myocardial volumes as confluent components of myocardial function. Further studies are needed to assess MFI amongst patients with varying etiologies of heart failure.