Normal Myocardial Perfusion Imaging Results Research Articles

Normal and Near Normal Myocardial Perfusion Imaging Data Analysis: Two-Year Major Adverse Cardiac Event

Myocardial perfusion imaging (MPI) is the method most commonly used to assess patients with suspected coronary artery disease for the presence of myocardial ischemia and risk of subsequent adverse cardiac events. Studies are limited on the incidence of major adverse cardiac event (MACE) in patients with normal MPI results. The aim of this study was to investigate the incidence and risk factors of MACE in patients with normal or near-normal MPI results. In this single-center retrospective chart review study, patients who had received MPI tests at a nuclear medicine department of a medical center in 2017 were consecutively enrolled. All of the participants in this study were patients with normal or near-normal MPI results, and were followed for two years to assess the incidence of MACE (death, hospitalized for percutaneous coronary intervention; CABG, heart failure and stroke). Participants with or without MACE were compared to determine whether demographic, comorbidity, and MPI data were significant risk factors. Of the 1,629 participants (age = 70.4 ± 11.3 years, 49.4% male) enrolled, 387 (23.8%) were classified into the normal MPI group and 1,242 (76.2%) were classified into the near-normal MPI group. Notably, 61 participants (15.8%) in the normal MPI group and 206 (16.6%) in the near-normal MPI group experienced MACE events during the two-year follow-up. The risk factors of MACE identified in this study included being older in age, being male, and having poor myocardial perfusion parameters (i.e., ejection fraction) during MPI. Over the two-year study period, 15.8% of the participants with normal MPI results and 16.6% of those with near-normal MPI results experienced major adverse cardiac events. Thus, it is critical to inform patients regarding the potential risk of MACE risk and to educate them on how to mitigate this risk by actively managing their hyperlipidemia level and left ventricular ejection fraction.

Are obesity indices derived by dual-energy x-ray absorptiometry capable of identifying postmenopausal females with high risk for coronary heart disease?

The aim of the study was to evaluate the predictive ability of obesity indices derived by dual-energy x-ray absorptiometry (DXA) regarding coronary heart disease (CHD). DXA total body scans were performed on 71 consecutive postmenopausal women who were referred for myocardial perfusion imaging (MPI). Twenty-four women with CHD diagnosed by MPI were considered as cases, whereas the remaining 47 women with normal MPI results were considered as controls. Biochemical markers, body mass index (BMI) and waist circumference (WC) were also recorded for all women and correlated to DXA adiposity indices. Receiver operating characteristic curve analysis was performed to evaluate the ability of DXA and anthropometrically obtained obesity indices on predicting CHD. Participants with CHD were found to have increased fat mass in the trunk (P < 0.01), in the android area (P < 0.01), and in the total body (P < 0.05) in agreement with the anthropometric indices WC (P < 0.01) and BMI (P < 0.05). Strong correlation was observed between BMI and fat mass in total body (R = 0.835), trunk (R = 0.731), and android (R = 0.796) and between WC and fat mass in android (R = 0.713). DXA-derived central fat indices were found to have higher potential for identification of individuals at high risk for CHD than BMI and WC but differences were not statistically significant. DXA central fat indices were found to have the power to identify individuals with CHD; however, the superiority of DXA indices over the commonly used anthropometric indices (BMI, WC) in identifying women with CHD did not reach statistical significance.

Very high coronary artery calcium score with normal myocardial perfusion SPECT imaging is associated with a moderate incidence of severe coronary artery disease.

PurposeMyocardial perfusion imaging (MPI) has limitations in the presence of balanced multivessel disease (MVD) and left main (LM) coronary artery disease, occasionally resulting in false-normal results despite the high cardiovascular risk associated with this condition. The purpose of this study was to assess the incidence of severe coronary artery disease (CAD) in the presence of a very high Agatston coronary artery calcium (CAC) score (>1,000) in stable symptomatic patients without known CAD but with normal MPI results.MethodsA total of 2,659 prospectively acquired consecutive patients were referred for MPI and evaluation of CAC score by CT. Of this patient population, 8 % (222/2,659) had ischemia without myocardial infarction (MI) on MPIand 11 % (298/2,659) had abnormal MPI (MI and/or ischemia). On presentation 1 % of the patients (26/2,659) were symptomatic, had a CAC score >1,000 and normal MPI results. The definition of normal MPI was strict and included a normal hemodynamic response without ischemic ECG changes and normal imaging, particularly absence of transient ischemic dilation. All of these 26 patients with a CAC score >1,000 and normal MPI findings underwent cardiac catheterization.ResultsOf these 26 patients, 58 % (15/26) had severe disease (≥70 % stenosis) leading to revascularization. Of this group, 47 % (7/15) underwent percutaneous intervention, and 53 % (8/15) underwent coronary artery bypass grafting. All of these 15 patients had either MVD (14/15) or LM coronary artery disease (1/15), and represented 0.6 % (15/2,659) of all referred patients (95 % CI 0.3 – 0.9 %). The majority, 90 % (8/9), had severe CAD with typical chest pain.ConclusionA very high CAC score (>1,000) with normal MPI in a small subset of symptomatically stable patients was associated with a moderate incidence of severe CAD (95 % CI 37 – 77 %). Larger studies and/or a meta-analysis of small studies are needed to more precisely estimate the incidence of CAD in this population. This study also supports the concept that a normal MPI result in patients with severe CAD may be due to balanced MVD.Electronic supplementary materialThe online version of this article (doi:10.1007/s00259-015-3072-z) contains supplementary material, which is available to authorized users.

Prognostic Value Of Normal Myocardial Perfusion Imaging In Asymptomatic Diabetic Patients With Moderate And High Calcium Scores

Abstract The purpose of this study was to evaluate the intermediate prognostic value of normal myocardial perfusion imaging (MPI) in asymptomatic diabetic patients with intermediate and high coronary artery calcium (CAC) scores. Methods: A total of 115 asymptomatic diabetic patients with no known coronary artery disease (CAD) underwent MPI after multi-slice computed tomography CAC assessment for the detection of suspected CAD. The study included 75 patients with normal MPI results. A 17-segment model for myocardial perfusion and function analysis was used. Patients were divided into three groups: I gr-20 patients with a diabetes duration between 1-5 years; II gr-24 patients with a diabetes duration 5-10 years; and III gr-31 patients with a diabetes duration &gt;10 years. End points (cardiac death, non-fatal myocardial infarction, heart failure, new angina, revascularization) were assessed at 6, 12 and 24 months. All patients had normal resting left ventricular function and normal myocardial perfusion scans. Forty patients had moderate coronary artery calcification with an average CAC of 290+/−95. Thirty-five patients had severe coronary calcification with an average CAC of 568+/−67. A correlation was found between diabetes duration and CAC severity (r-0,62 for diabetes duration over 10 years). Three cardiac events were identified at 24--month follow-up (new angina with percutaneous coronary intervention-PCI). Hard events (cardiac death, nonfatal myocardial infarction) were observed at a rate of 0% in group I, 4.2% in group II and 6.4% in group III. The overall event rate at 24--month follow-up was 4.0%. MPI and CAC are valuable techniques for the preclinical assessment of CAD in asymptomatic diabetic patients. This could guide decision-making to result in optimal treatment and prognosis. Even diabetic patients with normal MPI are at increased intermediate risk for CV events.

12-Year outcome after normal myocardial perfusion SPECT in patients with known coronary artery disease

BackgroundPrevious studies have reported a favorable outcome of patients with normal single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). The aim of this study was to assess the very long-term prognosis of patients with known coronary artery disease (CAD) and normal SPECT MPI results. MethodsThe population consisted of 266 patients with known CAD (defined as a healed myocardial infarction and/or a previous coronary revascularization), who underwent exercise bicycle or dobutamine-atropine stress SPECT MPI and had normal perfusion during stress and at rest. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction. Univariate and multivariate analyses were performed to identify predictors of long-term outcome. ResultsFollow-up was completed in 261 (98%) patients. During a median follow-up of 12 years, 94 (36%) patients died, of which 26 (10%) died due to cardiac causes, and 15 (6%) had a nonfatal myocardial infarction. The annualized mortality rate was 3.1%, annualized cardiac mortality rate was 0.9%, and the annualized event rate for cardiac death and/or nonfatal infarction was 1.2%. Independent predictors of total mortality were age, diabetes mellitus, and rate-pressure product at peak stress. Independent predictors of cardiac mortality were age, male gender, and rate-pressure product at peak stress. ConclusionPatients with known CAD and a normal SPECT MPI study have a favorable long-term prognosis. Clinical and stress test variables can be used to identify patients with a higher risk status.

Prediction of cardiovascular events in pre-dialysis chronic kidney disease patients with normal SPECT myocardial perfusion imaging

PurposePatients with normal stress myocardial perfusion imaging (MPI) results generally have an excellent prognosis with <1% cardiovascular events/year. Chronic kidney disease (CKD) is an established risk factor for cardiovascular events. However, the estimated glomerular filtration rate (eGFR) varies considerably among patients with CKD. We evaluated the prognostic value of eGFR for patients with CKD who did not undergo hemodialysis and had no evidence of coronary artery disease (CAD). Methods and subjectsPatients with CKD (n=108; 58 males; mean age: 74 years) with no CAD [no previous CAD and normal stress MPI results; summed stress score (SSS) <4] and with no history of hemodialysis were followed-up (mean duration: 24 months). CKD was defined by eGFR of <60ml/min/1.73m2 and/or persistent proteinuria. Cardiovascular events included cardiac death, non-fatal myocardial infarction, and unstable angina. ResultsCardiovascular events were observed in 8 patients with CKD (7%). The following were determined as significant predictors of these events: age (hazard ratio=1.14; p=0.019), hemoglobin levels (hazard ratio=0.69; p=0.021), eGFR (hazard ratio=0.94; p=0.008), SSS (hazard ratio=2.31; p=0.012), and summed difference score (hazard ratio=2.33; p=0.014). ConclusionsPatients with CKD and with no previous CAD and normal stress MPI results (SSS<4) may not exhibit an excellent cardiovascular prognosis. Further, a lower eGFR and stress MPI results may be the predictors of cardiovascular events. Thus, patients with a lower eGFR and/or normal stress MPI results (SSS<4) may require continuous follow-up.

Detection of Obstructive Coronary Artery Disease Using Regadenoson Stress and 82Rb PET/CT Myocardial Perfusion Imaging

Our objective was to study the diagnostic performance of regadenoson (82)Rb myocardial perfusion PET imaging to detect obstructive coronary artery disease (CAD). We studied 134 patients (mean age, 63 ± 12 y; mean body mass index, 31 ± 9 kg/m(2)) without known CAD (96 with coronary angiography and 38 with low pretest likelihood of CAD). Stress left ventricular ejection fraction (LVEF) minus rest LVEF defined LVEF reserve. The Duke score was used to estimate the anatomic extent of jeopardized myocardium. Regadenoson PET had a high sensitivity, 92% (95% confidence interval [CI], 83%-97%), in detecting obstructive CAD, with a normalcy rate of 97% (95% CI, 86%-99%), specificity of 77% (54/70 patients; 95% CI, 66%-86%), and area under the receiver-operator-characteristic curve of 0.847 (95% CI, 0.774-0.903; P < 0.001). Regadenoson PET demonstrated high sensitivity to detect CAD in patients with single-vessel CAD (89%; 95% CI, 70%-98%). The mean LVEF reserve was significantly higher in patients with normal myocardial perfusion imaging results (6.5% ± 5.4%) than in those with mild (4.3 ± 5.1, P = 0.03) and moderate to severe reversible defects (-0.2% ± 8.4%, P = 0.001). Also, mean LVEF reserve was significantly higher in patients with a low likelihood of CAD (7.2% ± 4.5%, P < 0.0001) and mild or moderate jeopardized myocardium than in those with significant jeopardized myocardium (score ≥ 6), -2.8% ± 8.3%. Regadenoson (82)Rb myocardial perfusion imaging is accurate for the detection of obstructive CAD. LVEF reserve is high in patients without significant ischemia or significant angiographic jeopardized myocardium.

Value of reserve pulse pressure in improving the risk stratification of patients with normal myocardial perfusion imaging

To evaluate the incremental prognostic value of reserve-pulse pressure (reserve-PP: exercise-PP minus rest-PP) to standard risk factors among patients with suspected coronary artery disease (CAD) but normal exercise myocardial perfusion imaging (MPI). We studied 4269 consecutive symptomatic patients without known CAD who were referred for exercise MPI but had normal MPI results (mean age 58 ± 12 years, 56% females, 84% referred for evaluation of chest pain or dyspnoea, 95% with intermediate pretest likelihood of CAD). There were 202 deaths over 5.1 ± 1.4 years of follow-up. Reserve-PP was abnormal (<44 mmHg increase in PP from rest) in 1894 patients (44%). Patients with an abnormal reserve-PP had a higher risk of death compared with patients with normal reserve-PP [hazard ratio (HR): 2.47, 95% CI, 1.8-3.3]. In multivariable models adjusting for age, sex, ejection fraction, medications, heart rate recovery, Duke treadmill score (DTS), and rest-PP, each 10 mmHg lower reserve-PP was associated with a 20.6% increase in risk-adjusted mortality (adjusted HR 0.83, 95% CI 0.76-0.91). Models incorporating reserve-PP significantly reclassified risk compared with models without these parameters (net reclassification index 14.3%, P = 0.0007; integrated discrimination index 0.69, P = 0.01). In patients without a history of CAD and a normal MPI, an abnormal reserve-PP identified and reclassified those at higher risk of death independent of known risk factors and DTS.

Diagnostic Value of 13N-Ammonia Myocardial Perfusion PET: Added Value of Myocardial Flow Reserve

The ability to obtain quantitative values of flow and myocardial flow reserve (MFR) has been perceived as an important advantage of PET over conventional nuclear myocardial perfusion imaging (MPI). We evaluated the added diagnostic value of MFR over MPI alone as assessed with (13)N-ammonia and PET/CT to predict angiographic coronary artery disease (CAD). Seventy-three patients underwent 1-d adenosine stress-rest (13)N-ammonia PET/CT MPI, and MFR was calculated. The added value of MFR as an adjunct to MPI for predicting CAD (luminal narrowing ≥ 50%) was evaluated using invasive coronary angiography as a standard of reference. Per patient, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MPI for detecting significant CAD were 79%, 80%, 91%, 59%, and 79%, respectively. Adding a cutoff of less than 2.0 for global MFR to MPI findings improved the values to 96% (P < 0.005), 80%, 93%, 89% (P < 0.005), and 92% (P < 0.005), respectively. The quantification of MFR in (13)N-ammonia PET/CT MPI provides a substantial added diagnostic value for detection of CAD. Particularly in patients with normal MPI results, quantification of MFR helps to unmask clinically significant CAD.

Stress-Only Tc-99m Myocardial Perfusion Imaging in an Emergency Department Chest Pain Unit

BackgroundStress-only myocardial perfusion imaging (MPI) saves time by eliminating rest imaging, which is important for emergency department (ED) throughput but has not been studied in an ED population. Study ObjectiveTo determine the prognosis of a normal stress-only MPI study compared to a normal rest-stress MPI and establish its effectiveness in an ED setting. MethodsAll patients evaluated in the ED over 6.5 years who underwent a stress-only technetium-99m gated MPI were compared to those who had a rest-stress study. All-cause mortality was determined using the Social Security Death Index. Survival was analyzed in patients with normal and abnormal MPI results. ResultsA total of 4145 studies (2340 stress-only, 1805 rest-stress) were performed. Patients’ average age was 57.9 years, 38.5% were male, and most had an intermediate or low pretest risk of coronary artery disease (87.7%). Average follow-up was 35.9 ± 20.9 months. In patients with normal perfusion, at 1 year of follow-up there were 11 deaths in the stress-only group (0.5% 1-year mortality), and 13 deaths in the rest-stress cohort (1.1% 1-year mortality). At the end of follow-up, the stress-only group had a lower all-cause mortality (p < 0.0001) and similar risk adjusted all-cause mortality (p = 0.10) than the rest-stress cohort. Patients with abnormal perfusion demonstrated the expected differential prognosis based on total perfusion deficits in both groups. ConclusionsA normal stress-only MPI study has a benign 1-year prognosis similar to a rest-stress study when performed in the ED. The ability to triage patients more rapidly and reduce radiation exposure represents an attractive alternative for low-risk patients.

Significant Coronary Calcification Detected Using Contrast-Enhanced Computed Tomography

Evaluate the significance of coronary arteries calcifications detected using contrast-enhanced chest computed tomography (CECCT) scans. A total of 145 patients who underwent both CECCT and gated stress myocardial perfusion imaging (MPI) within 2 weeks were included. The chest CT scans were reviewed for the presence of coronary artery calcium (CAC) by 2 experienced blinded readers. The degree of calcifications seen in any visualized area of the major coronary arteries was graded on a scale of 1 to 3 (1 when 0 to 4 small scattered plaques were seen, 2 when 5 or more scattered plaques were seen, and 3 when diffuse contiguous calcification were seen). The grade of CAC was correlated with the presence of MPI abnormalities. Additionally, the locations of the MPI abnormality was correlated with the CAC grade in the culprit coronary artery. Of 580 major coronary arteries evaluated, 79% had grade 1 CAC, 10% had grade 2, 11% had grade 3, and 1% were inevaluable. Of the 145 patients, 33 (23%) had abnormal MPI results. Twenty-three of the patients with abnormal MPI results (70%) had more than 4 calcified plaques (CAC grade of 2 or 3) in one or more of their coronary arteries, whereas 41 of 122 patients with normal MPI results (37%) had similar CAC grades (P=0.001). Seventeen of the 33 patients (52%) who had MPI defects also had significant CAC in the culprit coronary artery, 7 patients (21%) had significant CAC in a different coronary artery from the MPI defect territory, 8 patients (24%) had no significant CAC visualized, and in 1 patient a pacemaker wire interfered with CAC grading in the culprit coronary artery (RCA). The sensitivity, specificity, the positive, and negative predictive values of grade 2 or 3 CAC for an abnormal MPI results were 70%, 63%, 36%, and 88%, respectively. When a subgroup of patients above 60 years old with grade 3 CAC was reanalyzed, the sensitivity, specificity, the positive, and negative predictive values for an abnormal MPI results were 69%, 73%, 41%, and 90%, respectively. Multiple diffuse CAC as detected during the interpretation of CECCT scans in combination with advanced age is a significant finding that warrants further investigation for functionally significant CAD.

Negative predictive value and potential cost savings of acute nuclear myocardial perfusion imaging in low risk patients with suspected acute coronary syndrome: A prospective single blinded study

BackgroundPrevious studies from the USA have shown that acute nuclear myocardial perfusion imaging (MPI) in low risk emergency department (ED) patients with suspected acute coronary syndrome (ACS) can be of clinical value. The aim of this study was to evaluate the utility and hospital economics of acute MPI in Swedish ED patients with suspected ACS.MethodsWe included 40 patients (mean age 55 ± 2 years, 50% women) who were admitted from the ED at Lund University Hospital for chest pain suspicious of ACS, and who had a normal or non-ischemic ECG and no previous myocardial infarction. All patients underwent MPI from the ED, and the results were analyzed only after patient discharge. The current diagnostic practice of admitting the included patients for observation and further evaluation was compared to a theoretical "MPI strategy", where patients with a normal MPI test would have been discharged home from the ED.ResultsTwenty-seven patients had normal MPI results, and none of them had ACS. MPI thus had a negative predictive value for ACS of 100%. With the MPI strategy, 2/3 of the patients would thus have been discharged from the ED, resulting in a reduction of total hospital cost by some 270 EUR and of bed occupancy by 0.8 days per investigated patient.ConclusionOur findings in a Swedish ED support the results of larger American trials that acute MPI has the potential to safely reduce the number of admissions and decrease overall costs for low-risk ED patients with suspected ACS.

The clinical implications of myocardial perfusion abnormalities in patients with esophageal or lung cancer after chemoradiation therapy

This study aims to identify the clinical implications of myocardial perfusion defects after chemoradiation therapy (CRT) in patients with esophageal and lung cancer. We retrospectively compared myocardial perfusion imaging (MPI) results before and after CRT in 16 patients with esophageal cancer and 24 patients with lung cancer. New MPI defects in the radiation therapy (RT) fields were considered related to RT. Follow-up to evaluate for cardiac complications and their relation with the results of MPI was performed. Statistical analysis identified predictors of cardiac morbidities. Eleven females and twenty nine males at a mean age of 66.7 years were included. Five patients (31%) with esophageal cancer and seven patients (29%) with lung cancer developed myocardial ischemia in the RT field at mean intervals of 7.0 and 8.4 months after RT. The patients were followed-up for mean intervals of 15 and 23 months in the esophageal and lung cancer groups, respectively. Seven patients in each of the esophageal (44%) and lung (29%) cancer patients (P = 0.5) developed cardiac complications of which one patient with esophageal cancer died of complete heart block. Six out of the fourteen patients (43%) with cardiac complication had new ischemia on MPI after CRT of which only one developed angina. The remaining eight patients with cardiac complications had normal MPI results. MPI result was not a statistically significant predictor of future cardiac complications after CRT. A history of congestive heart failure (CHF) (P = 0.003) or arrhythmia (P = 0.003) is a significant predictor of cardiac morbidity after CRT in univariate analysis but marginal predictors when multivariate analysis was performed (P = 0.06 and 0.06 for CHF and arrhythmia, respectively). Cardiac complications after CRT are more common in esophageal than lung cancer patients but the difference is not statistically significant. MPI abnormalities are frequently seen after CRT but are not predictive of future cardiac complications. A history of arrhythmia or CHF is significantly associated with cardiac complications after CRT.

Anatomic Correlates of a Normal Perfusion Scan Using 64-Slice Computed Tomographic Coronary Angiography

Both myocardial perfusion imaging (MPI) and multislice computed tomography (MSCT) are currently used to detect coronary artery disease (CAD). However, MSCT permits early detection of atherosclerosis while myocardial perfusion is still normal. In addition, MPI results can be normal despite the presence of high-risk CAD (left main and balanced 3-vessel CAD). In this study, the range of anatomic findings using MSCT in patients with normal MPI results was evaluated. In 180 patients presenting with chest pain, MPI (with gated single-photon emission computed tomography) and 64-slice MSCT were performed. In patients with normal MPI results, prevalences of completely normal coronary arteries, nonobstructive CAD, and obstructive CAD were determined using MSCT. The occurrence of high-risk CAD, including left main and 3-vessel disease, was also evaluated. Normal MPI and adequate MSCT findings were obtained in 97 patients (54%; 50% women; average age 58 +/- 12 years; 5% with known CAD). A total of 38 patients (39%) showed normal coronary anatomy, whereas nonsignificant and significant CAD were observed in 37 (38%) and 18 patients (19%), respectively. Importantly, only 4 patients (4%) presented with high-risk CAD using 64-slice MSCT, 2 with left main and 2 with 3-vessel disease. In conclusion, a normal MPI result can be associated with a wide range of anatomic observations and cannot exclude the presence of both nonobstructive and obstructive CAD. However, importantly, the prevalence of high-risk CAD was rare.

Relation of Brachial Artery Flow-Mediated Vasodilation to Significant Coronary Artery Disease in Patients With Peripheral Arterial Disease

In patients at risk for coronary atherosclerosis, brachial artery flow-mediated dilation (FMD) rules out significant coronary artery disease (CAD). However, the value of this approach is unknown in patients with peripheral arterial disease who are at increased risk for CAD. This study assessed whether the noninvasive evaluation of endothelial function by brachial artery FMD rules out significant CAD by dipyridamole myocardial perfusion imaging (MPI) in patients with peripheral arterial disease who are asymptomatic for CAD. Forty-four patients with peripheral arterial disease who were asymptomatic for CAD underwent, in the same day, FMD evaluation and dipyridamole MPI using technetium-99m sestamibi single photon-emission computed tomography. MPI results were abnormal in 17 of 44 patients (39%). FMD was significantly less (6.0 +/- 2.3%) in patients with abnormal MPI results compared with those with normal MPI results (7.3 +/- 1.8%, p = 0.04). By multivariate analysis, FMD was the only significant predictor of abnormal MPI results (odds ratio 0.63, p = 0.02). Receiver-operating characteristic curve analysis assessing the ability of FMD to identify patients with summed stress scores > or =3 yielded an area under the curve of 0.74 (p = 0.009). A FMD value >6% provided 92% negative predictive power to rule out abnormal MPI results, with sensitivity of 79% and specificity of 73%. In conclusion, the noninvasive evaluation of endothelial function by FMD has high negative predictive accuracy and good sensitivity and specificity to detect abnormal MPI results in patients with peripheral arterial disease. Thus, it may represent a valuable screening test to rule out significant CAD in these patients.

Spect myocardial perfusion imaging in the morbidly obese: Prognosis and diagnostic value

Background: Obesity is a growing epidemic in the US. As little is known about the diagnostic accuracy of myocardial perfusion imaging (MPI) in the morbidly obese (BMI ≥ 40), we set out to evaluate the correlation of MPI with coronary angiography and the prognostic value of normal studies. Methods: We retrospectively studied 433 consecutive morbidly obese patients without known coronary artery disease presenting for a clinically indicated Tc-99m SPECT MPI study over a 42 months period. A subset of 43 subjects subsequently underwent coronary angiography whose results were compared to MPI. Hospital records and the Social Security Death Index were searched to assess all-cause mortality. Results: Of the 433 patients reviewed 139 (32%) had abnormal MPI results and 294 (68%) normal results. Comparing the patients with abnormal MPI results to normal MPI, the average age was 55 ± 12 versus 53 ± 11 years, BMI 46.9 ± 7 versus 47.5 ± 8 kg/m 2, weight 285 ± 58 versus 275 ± 63 lbs, and Tc99m dose of 36.2 ± 4.3 versus 35.3 ± 5.9 mCi (all p=NS). Of the 43 patients who underwent angiography, performed a median of 15 days later, 5 were performed on patients with normal MPI studies and 38 on patients with abnormal studies. Stress MPI had a sensitivity of 95%, specificity of 17%, positive predictive value of 50%, and negative predictive value of 80% for the detection of > 50% epicardial vessel stenosis. At one year of follow-up, 9 of the 295 patients (3.1%) with a normal MPI died during the follow-up (669 ± 307 days) yielding a 96.9% 1 year survival. Of the 139 patients with an abnormal MPI, 9 (6.5%) died during follow-up (719 ± 318 days) yielding a 93.5% 1 year survival. Conclusion: In the morbidly obese population, stress SPECT MPI imaging has high sensitivity and poor positive predictive value when compared to coronary angiography. One year mortality of the morbidly obese with a normal MPI study (3.1%) exceeds published expected mortality of patients with normal MPI results, as well as diabetic patients with normal MPI results.