Acute beta-blockade reduces the extent and severity of myocardial perfusion defects with dipyridamole Tc-99m sestamibi SPECT imaging

Effect of Beta-Blocker Consumption on the Severity and Extension of Perfusion Defects in Dipyridamole Myocardial Perfusion Single-Photon Emission Computed Tomography

Background  Regarding the less-known effects of beta-blocker consumption on the diagnostic value of the myocardial perfusion scan with dipyridamole stress in coronary artery disease (CAD), we aimed to compare the findings of the scans done on the beta-blocker consumption course and after discontinuation of this medications. Materials and Methods  Thirty patients with probably CAD and abnormal myocardial perfusion scans (presence of reversible defect), who had been treated with beta-blockers for at least 3 months, were studied. Dipyridamole stress phase of myocardial perfusion single-photon emission computed tomography (SPECT) was performed two times with an interval of about 1 week, once after discontinuation of all antianginal and anti-ischemic medications, statins, and beta-blockers for 72 hours prior to the study, and again after discontinuation of all these medications except for beta-blockers. Imaging was done with the same protocol, radiopharmaceutical dose, and imaging parameters. Summed stress score (SSS), summed stress rest, and summed difference scores (SDS), total perfusion deficit (TPD), severity, and extension of myocardial perfusion defects in three coronary artery territories were analyzed, using quantitative perfusion SPECT software. Results  Most variables such as SSS, SDS, TPD, severity, and extension of defects showed a significant difference between the two conditions including beta-blocker consumption and after discontinuing beta-blocker consumption before stress imaging ( p  < 0.05). Moreover, in patients on treatment with metoprolol, all studied factors including SSS, SDS, TPD, severity, and extension of perfusion defects were significantly reduced when patients consumed beta-blockers before SPECT evaluation ( p  < 0.05). Conclusion  Beta-blocker consumption can lead to a decrease in the severity and extent of myocardial perfusion defects and therefore probably a decrease in the sensitivity of myocardial scans. Discontinuation of beta-blocker prior to the dipyridamole myocardial perfusion scan can improve diagnostic accuracy.

Effect of acute intravenous beta-blocker administration on myocardial blood flow during same-day hybrid CCTA/PET imaging

This study aimed to evaluate the impact of acute intravenous beta-blocker administration on myocardial blood flow (MBF) during same-day hybrid coronary computed tomography angiography (CCTA) and 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI). Previous research on the discontinuation of oral beta-blockers before MPI has shown mixed results, with no studies yet exploring the acute intravenous administration in the context of same-day hybrid imaging. This retrospective study included patients with suspected chronic coronary syndromes undergoing same-day hybrid CCTA/13N-ammonia PET MPI. Exclusion criteria comprised coronary artery stenosis ≥ 50% or regional perfusion abnormalities on PET, and baseline oral beta-blocker medication. Intravenous metoprolol (up to 30 mg) was administered as needed for heart rate control before CCTA. MBF measurements were obtained at rest (rMBF) and during stress (sMBF), and myocardial flow reserve (MFR) was calculated. After excluding 281 patients, 154 were eligible for propensity-score matching, resulting in 108 patients divided into two equal groups based on beta-blocker administration. The groups showed no significant differences in baseline characteristics. Among those who received beta-blockers, there was a significant decrease in sMBF (2.21 [IQR 1.72-2.78] versus 2.46 [2.08-2.99] ml∙min-1∙g-1, p = 0.027) and MFR (3.46 [2.70-4.05] versus 3.79 [3.22-4.46], p = 0.030), respectively, compared to those who did not receive beta-blockers. In contrast, rMBF remained unaffected (0.65 [0.54-0.78] versus 0.64 [0.55-0.76] ml∙min-1∙g-1, p = 0.931). Acute intravenous beta-blocker administration significantly impacts MBF, leading to a slight reduction in sMBF and MFR. In contrast, rMBF appears unaffected, suggesting that beta-blockers primarily affect the coronary capacity to respond to vasodilators.

Medication and ECG Patterns That May Hinder SPECT Myocardial Perfusion Scans

Coronary artery disease (CAD) is the leading cause of death followed by cancer, in men and women. With risk factors being endemic and the increasing costs of healthcare for management and treatment, myocardial perfusion imaging (MPI) finds a central role in risk stratification and prognosis for CAD patients, but it comes with its limitations in that the referring clinician and managing team must be aware of and use at their advantage. This narrative review examines the utility of myocardial perfusion scans in the diagnosis and management of patients with ECG alterations such as atrioventricular block (AVB), and medications including calcium channel blockers (CCB), beta blockers (BB), and nitroglycerin which may impact the interpretation of the exam. The review analyzes the current evidence and provides insights into the limitations, delving into the reasons behind some of the contraindications to MPI.

Amiodarone attenuates cardiac Rubidium-82 in consecutive PET/CT scans in a rodent model

BACKGROUND

Risk stratification and diagnosis using Rubidium-82 (82Rb) positron emission tomography (PET) is a routine clinical approach in coronary artery disease (CAD). Various drugs are used to treat CAD; however, whether any of them change the uptake of 82Rb in the heart has not been investigated. The aim of this study is to determine whether drugs used in treatment of CAD affect the uptake of 82Rb in the heart in healthy rats.

METHODS

Seventy-seven Sprague-Dawley rats were included in the cross-sectional study. All rats underwent baseline 82Rb PET/CT and divided into eleven groups treated with different drugs. One group was control group (no treatment), eight groups were treated with monotherapy (amiodarone, acetylsalicylic acid (ASA), clopidogrel, ticagrelor, atorvastatin, enalapril, amlodipine, metoprolol succinate), and two groups were treated with polypharmacy (ASA, ticagrelor, atorvastatin, amlodipine or ASA, clopidogrel, atorvastatin, amlodipine). Once a day, they were administered pharmacological therapy through oral gavage, and on day seven, follow-up scanned with 82Rb PET/CT.

RESULTS

In the control group without pharmacological treatment, no difference in the standard uptake value (SUV) ratio between heart and muscle from baseline to follow-up (5.8 vs 7.0, P = .3) was found. The group treated with amiodarone had a significantly reduced SUV ratio from baseline to follow-up (5.8 vs 5.1, P = .008). All other drugs investigated had no difference in SUV ratio from baseline to follow-up.

CONCLUSION

In this study, we showed that drugs normally used to treat CAD do not affect the uptake of 82Rb. However, amiodarone result in a significantly lowered 82Rb uptake, compared to control. This information about amiodarone would probably not change the size assessment of a myocardial perfusion defect in a clinical setting. However, it could change the kinetic parameters when assessing absolute myocardial blood flow in patients treated with amiodarone.

Drug Use Evaluation of Beta-Blockers in Medical Wards of Nedjo General Hospital, Western Ethiopia

Introduction

Beta-blocker use evaluation is a performance method that focuses on the evaluation of beta-blocker use processes to achieve optimal patient outcomes. Several studies conducted in different hospitals revealed a high incidence of inappropriate prescription of beta-blockers among hospitalized patients. Therefore, it is important to identify inappropriate beta-blocker prescribing since they may increase the risk of hospitalizations. Despite this, there was no study conducted related to drug use evaluation of beta-blockers in Nedjo general hospital (NGH). Thus, this study was aimed at assessing the use evaluation of beta-blockers in medical wards of NGH.

Methods

A retrospective cross-sectional study was conducted at medical wards of NGH from January 1, 2016, to December 31, 2017.

Results

Out of the total of 149 medical record of patients that contains beta-blockers, 84 (56.37%) were males and about one-third (31.54%) of the patients ages were between 41 and 50 years. Propranolol was the most commonly prescribed beta-blocker (62.76%), and 94.56% of beta-blockers were prescribed with correct indication. There were about 51%, 46.31%, 64.43%, and 46.98% of beta-blockers prescribed with the correct dose, duration, frequency, and route of administration, respectively. Regarding the routes of administration, 70 (46.98%) of them were prescribed with the correct route. Most drugs interacting were propranolol with cimetidine 26 (68.42%), and the most frequent condition for which beta-blockers were prescribed was hypertension (32.89%).

Conclusion

Overall, there was an inappropriate use of beta-blockers in terms of dosage and durations. So, prescribers of NGH should strictly adhere to the national treatment guideline when prescribing medications. Additionally, drug information centers have proved useful and effective in promoting rational drug use. Hence, it should be recommended for general use.

A multi-scale model of the coronary circulation applied to investigate transmural myocardial flow

Distribution of blood flow in myocardium is a key determinant of the localization and severity of myocardial ischemia under impaired coronary perfusion conditions. Previous studies have extensively demonstrated the transmural difference of ischemic vulnerability. However, it remains incompletely understood how transmural myocardial flow is regulated under in vivo conditions. In the present study, a computational model of the coronary circulation was developed to quantitatively evaluate the sensitivity of transmural flow distribution to various cardiovascular and hemodynamic factors. The model was further incorporated with the flow autoregulatory mechanism to simulate the regulation of myocardial flow in the presence of coronary artery stenosis. Numerical tests demonstrated that heart rate (HR), intramyocardial tissue pressure (P_im ), and coronary perfusion pressure (P_per ) were the major determinant factors for transmural flow distribution (evaluated by the subendocardial-to-subepicardial (endo/epi) flow ratio) and that the flow autoregulatory mechanism played an important compensatory role in preserving subendocardial perfusion against reduced P_per . Further analysis for HR variation-induced hemodynamic changes revealed that the rise in endo/epi flow ratio accompanying HR decrease was attributable not only to the prolongation of cardiac diastole relative to systole, but more predominantly to the fall in P_im . Moreover, it was found that P_im and P_per interfered with each other with respect to their influence on transmural flow distribution. These results demonstrate the interactive effects of various cardiovascular and hemodynamic factors on transmural myocardial flow, highlighting the importance of taking into account patient-specific conditions in the explanation of clinical observations.

The influence of clopidogrel on ischemia diagnosed by myocardial perfusion stress testing

BACKGROUND

Clopidogrel is a platelet adenosine receptor antagonist which can influence coronary vascular tone and thus can potentially interfere with myocardial perfusion imaging. We investigated whether clopidogrel can hamper the diagnosis of ischemia in patients undergoing myocardial perfusion testing.

METHODS

Data from a database of 6349 myocardial perfusion stress tests were analyzed. Using a propensity analysis, patients who were taking clopidogrel were compared with patients not taking clopidogrel for the presence of reversible perfusion defects on myocardial single-photon emission computed tomography scans.

RESULTS

Of the 6349 tests, the stress technique was adenosine in 2713 patients and exercise in 3636. At the time of the stress test, 277 (4.3%) of the patients were taking clopidogrel. The odds ratio (OR) for patients taking clopidogrel to have a reversible perfusion defect was 2.75 (95% confidence interval [CI] 2.09-3.62; P < .01). After adjusting for the propensity to take clopidogrel, the OR was 1.06 (CI 0.76-1.49; P = .73) for patients undergoing adenosine stress tests and 1.60 (CI 0.85-3.00; P = .14) for patients undergoing exercise stress tests.

CONCLUSIONS

We found no evidence that the use of clopidogrel decreases the likelihood of ischemia on adenosine or exercise stress myocardial perfusion scans.

Effect of changes in perfusion defect size during serial regadenoson myocardial perfusion imaging on cardiovascular outcomes in high-risk patients

BACKGROUND

The prognostic value of single-photon emission computed tomography myocardial perfusion imaging (MPI) is well established. There is a paucity of data on the prognostic value of changes in perfusion defect size (PDS) on serial MPIs.

METHODS

From the MPI database at the University of Alabama at Birmingham, consecutive patients who underwent two regadenoson stress MPIs between July 2008 and March 2013 were identified. The MPIs were analyzed side-by-side using an automated software program for presence and change in PDS. Improvement in PDS was defined as a reduction ≥5% of left ventricle. A drop in left ventricular ejection fraction (LVEF) was defined as a decrease ≥5%. The primary outcome was a composite of death, myocardial infarction (MI), and coronary revascularization (CR).

RESULTS

There were 698 patients (61 ± 11 years, 53% male, 48% diabetes, 25% prior MI, 49% prior CR) who underwent two regadenoson MPIs within 16 ± 9 months for clinical indications. The primary outcome occurred in 167 (24%) patients (8% death, 9% MI, 15% CR) during 24 ± 16 months of follow-up after the second MPI. The MPIs were normal in both studies in 399 (57%, Group 1), showed improvement in 94 (14%, Group 2, PDS 15% ± 16% vs 28% ± 18%, P < .001) and no change or worsening in 205 patients (29%, Group 3, 28% ± 17% vs 20% ± 17%, P < .001). The best outcomes were seen in Group 1 and the worst in Group 3 (log-rank P < .001). Similar trends were seen for the components of the primary outcome (P = .04 for death, P < .001 for MI, P < .001 for CR). In a Cox-regression model that adjusted for baseline factors including PDS and LVEF on initial MPI, the hazard ratios for primary outcome were 2.0 (P = .02) and 3.9 (P < .001) for Groups 2 and 3 compared to Group 1, respectively. In addition, an LVEF drop ≥5% was independently associated with the primary outcome (HR 1.5, P = .01).

CONCLUSION

Changes in PDS and LVEF on serial MPIs provide incremental prognostic information to initial and follow-up MPI findings. Lack of improvement or an increase in PDS and a drop in LVEF identify high-risk patients.

The effect of beta blocker withdrawal on myocardial SPECT modeled from adenosine 13N-ammonia PET

AIM

The effect of beta blockers (BB) on myocardial imaging has been studied in several SPECT and PET studies with divergent results concerning perfusion and impact on diagnostic accuracy. The present study evaluated the effect of BB withdrawal on virtual SPECT studies modeled from quantitative PET perfusion scans.

PATIENTS, METHODS

Data from 20 CAD patients scheduled for adenosine 13N-ammonia imaging with and without BB were considered. Modeling the uptake characteristics of 99mTc-MIBI, all parametric stress PET polarmaps were transferred to virtual 20-segment SPECT polarmaps. The SPECT studies were categorized with a 5-point score and read to assess the effect of the BB withdrawal on scan result and interpretation.

RESULTS

The SPECT analysis revealed a mean score of 6.0 ± 4.7 with, and of 5.9 ± 4.5 without BB (p = 0.84). In 260 (74.9%) segments the scores were equal in both conditions. Without BB a downstaging was recorded in 44 segments (12.7%), an upstaging in 43 segments (12.4%). An essentially different interpretation (shift from medical therapy recommendation to angiography) was recorded in one patient. In six cases the interpretation differed mildly.

CONCLUSION

In the majority of patients studied, scan results and interpretation remain unchanged after discontinuation of the BB. Nevertheless, the segmental scan results are not uniformly affected. The recommendation to stop BBs prior to stress testing in order to ensure the highest MBF remains advisable. If temporary BB withdrawal is unfeasible due to contraindications, a tight clinical schedule, or because a patient forgot to withhold the BB, it is appropriate to perform adenosine stress testing according to the results of this study.

Cardiovascular Response to Exercise Testing in Children and Adolescents Late After Kawasaki Disease According to Coronary Condition Upon Onset

Multiple cardiovascular sequelae have been reported late after Kawasaki disease (KD), especially in patients with coronary artery lesions. In this perspective, we hypothesized that exercise response was altered after KD in patients with coronary aneurysms (CAA-KD) compared to those without history of coronary aneurysms (NS-KD). This study is a post hoc analysis of exercise data from an international multicenter trial. A group of 133 CAA-KD subjects was compared to a group of 117 NS-KD subjects. Subjects underwent a Bruce treadmill test followed to maximal exertion. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were assessed at each stage of the test including recovery. Myocardial perfusion was evaluated by stress and rest Tc-99m sestamibi SPECT imaging. Endurance time was similar between NS-KD and CAA-KD (11.3 ± 2.6 vs. 11.0 ± 2.6 min; p = 0.343). HR, SBP, and DBP responses to exercise were similar between groups (p = 0.075-0.942). Myocardial perfusion defects were present in 16.5 % CAA-KD versus 22.2 % NS-KD (p = 0.255). Analysis based on myocardial perfusion status identified a lower heart rate at 1 min into recovery as well as lower DBP at 1 and 5 min into recovery in patients with abnormal SPECT imaging (p = 0.017-0.042). Compared to patients without CA involvement, the presence of coronary aneurysms at the subacute phase of KD does not induce a differential effect on exercise parameters. In contrast, exercise-induced myocardial perfusion defect late after the onset of KD correlates with abnormal recovery parameters.

Defining the optimal systolic phase targets using absolute delay time for reconstructions in dual-source coronary CT angiography

To define the optimal systolic phase for dual-source computed tomography angiography using an absolute reconstruction delay time after the R-R interval based on the coronary artery motion, we analyzed images reconstructed between 200 and 420 miliseconds (ms) after the R wave at 20 ms increments in 21 patients. Based on the American Heart Association coronary segmentation guidelines, the origin of six coronary artery landmarks (RCA, AM1, PDA, LM, OM1, and D2) were selected to calculate the coronary artery motion velocity. The velocity of the given landmark was defined as the quotient of the route and the length of the time interval. The x, y and z-coordinates of the selected landmark were recorded, and were used for the calculation of the 3D route of coronary artery motion by using a specific equation. Differences in velocities were assessed by analysis of variance for repeated measures; Bonferroni post hoc tests were used for multiple pair wise comparisons. 1488 landmarks were measured (6 locations at 12 systolic time points) in 21 patients and were analyzed. The mean values of the minimum velocities were calculated separately for each heart rate group (i.e. <65; 65-80; and >80 bpm). The mean lowest coronary artery velocities in each segment occurred in the middle period of each time interval of the acquired systolic phase i.e. 280-340 ms. No differences were found in the minimal coronary artery velocities between the three HR groups, with the exception of the AM1 branch (p = 0.00495) between <65 and >80 bpm (p = 0.03), and at HRs of 65-80 versus >80 bpm (p = 0.006). During an absolute delay of 200-420 ms after the R-wave, the ideal reconstruction interval varies significantly among coronary artery segments. Decreased velocities occur between 280 to 340 ms. Therefore a narrow range of systolic intervals, rather than a single phase, should be acquired.

Serial myocardial perfusion imaging: defining a significant change and targeting management decisions

Myocardial perfusion imaging (MPI) with gated single-photon emission tomography provides important information on the extent and severity of myocardial perfusion abnormalities, including myocardial ischemia. The availability of software for automated quantitative assessment of myocardial perfusion in an objective and more reproducible manner than visual assessment has allowed MPI to be particularly effective in serial evaluation. Serial testing using MPI is widely used in guiding patient care despite the lack of well-defined appropriateness use criteria. This should not be surprising because ischemic heart disease is a life-long malady subject to dynamic changes throughout its natural course and particularly following man-made interventions that may improve or worsen the disease process, such as medical therapy and coronary revascularization. Serial MPI has filled an important clinical gap by providing crucial information for managing patients with changes in clinical presentations or in anticipation of such changes in patients with stable symptoms. In the research arena, serial MPI has been widely applied in randomized controlled trials to study the impact of various medical and interventional therapies on myocardial perfusion, as well as the relative merits of new imaging procedures (hardware and/or software), radiotracers, and stressor agents. Serial testing, however, unlike initial or 1-time testing, has more stringent requirements and is subject to variability because of technical, procedural, interpretational, and biological factors. The intrinsic variability of MPI becomes important in interpreting serial tests in order to define a true change in a given patient and to guide clinical decision making. The purpose of this first comprehensive review on this subject is to illustrate where serial MPI may be useful clinically and in research studies, and to highlight strategies for addressing the various issues that are unique to serial testing in order to derive more valid and robust data from the serial scans.

The effect of beta blocker withdrawal on adenosine myocardial perfusion imaging

BACKGROUND

The effect of beta blockers on myocardial blood flow (MBF) under vasodilators has been studied in several SPECT and PET myocardial perfusion imaging (MPI) studies with divergent results. The present study evaluated the effect of a beta blocker withdrawal on quantitative adenosine MBF and on MPI results.

METHODS

Twenty patients with beta blockers and CAD history were studied with quantitative adenosine N-13 ammonia PET. The first study was performed under complete medication and the second after beta blocker withdrawal. The PET studies were independently read with respect to MPI result and clinical decision making.

RESULTS

Global MBF showed an increase from 180.2 ± 59.9 to 193.6 ± 60.8 mL·minute(-1)/100 g (P = .02) after beta blocker withdrawal. The segmental perfusion values were closely correlated (R(2) = 0.82) over the entire range of perfusion values. An essentially different interpretation after beta blocker discontinuation was found in two cases (10%).

CONCLUSION

A beta blocker withdrawal induces an increase in adenosine MBF. In the majority of cases, MPI interpretation and decision making are independent of beta blocker intake. If a temporary beta blocker withdrawal before MPI is not possible or was not realized by the patient, it is appropriate to perform adenosine stress testing without loss of the essential MPI result.

Arm exercise myocardial perfusion imaging for prognostication of long-term outcome

INTRODUCTION

Pharmacologic evaluations constitute ≥50% of imaging stress tests, but exercise reduces adverse effects, improves myocardial perfusion imaging (MPI) quality and diagnostic results, and provides powerful prognostic and clinically important information on exercise capacity and cardiovascular responses to the relevant physiologic stress of exercise. Thus, our purpose was to determine whether arm exercise and MPI variables predict long-term outcome in patients who cannot perform leg exercise.

METHODS

We performed arm exercise MPI stress tests in 253 consecutive patients age 64.5 (10.7) yr (mean (SD)) from 1997 to 2002 and investigated associations of arm exercise and abnormal MPI variables with all-cause mortality, myocardial infarction (MI), coronary artery bypass grafting (CABG), and percutaneous coronary intervention (PCI) during follow-up of 12.0 (1.3) yr.

RESULTS

There were 156 deaths (61.7%), 47 patients suffered MI (18.6%), 24 underwent CABG (9.5%), and 50 had PCI (19.8%). Arm exercise capacity and delta HR (peak - resting) were strongly associated with survival after adjustment for significant demographic and clinical variables (Cox multivariate P < 0.0001 and 0.001, respectively). MPI was abnormal in 157 patients (62.1%). An abnormal arm exercise MPI was borderline predictive of mortality by Cox analysis (71.8% vs 46.4% for normal study; univariate P < 0.0001; multivariate P = 0.07) but resulted in 58% relative incremental integrated discrimination improvement over clinical variables for predicting death. Perfusion defect size also strongly predicted mortality (Cox multivariate P = 0.003). An abnormal arm exercise MPI study, perfusion defect type, and size all prognosticated PCI (all P ≤ 0.03) but not MI or CABG.

CONCLUSIONS

Arm exercise MPI is a valuable approach for outcome prediction in patients unable to perform leg exercise.

Improved diagnosis and prognosis using Decisions Informed by Combining Entities (DICE): results from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE)

OBJECTIVES

To introduce an algorithmic approach to improve the interpretation of myocardial perfusion images in women with suspected myocardial ischemia.

BACKGROUND

Gated single photon emission computed tomography (SPECT) and magnetic resonance (MR) myocardial perfusion imaging (MPI) approaches have relatively poor diagnostic and prognostic value in women with suspected myocardial ischemia. Here we introduce an approach: Decisions Informed by Combining Entities (DICE) that forms a mathematical model utilizing MPI and cardiac dimensions generated by one modality to predict the perfusion status of another modality. The effect of the model is to systematically incorporate cardiac metrics that influence the interpretation of perfusion images, leading to greater consistency in designation of myocardial perfusion status between studies.

METHODS

Women (n=213), with suspected myocardial ischemia, underwent MPI assessment for regional perfusion defects using two modalities: gated SPECT (n=207) and MR imaging (n=203). To determine perfusion status, MR data were evaluated qualitatively and semi-quantitatively while SPECT data were evaluated using conventional clinical criteria. These perfusion status readings were designated "Original". Four regression models were generated to model perfusion status obtained with one modality [e.g., semi-quantitative magnetic resonance imaging (MRI)] against another modality (e.g., SPECT) and a threshold applied (DICE modeling) to designate perfusion status as normal or low. The DICE models included perfusion status, left ventricular (LV) chamber volumes and myocardial wall thickness. Women were followed for 40±16 months for the development of first major adverse cardiovascular event (MACE: CV death, nonfatal myocardial infarction (MI) or hospitalization for congestive heart failure). Original and DICE perfusion status were compared in their ability to detect high-grade coronary artery disease (CAD) and for prediction of MACE.

RESULTS

Adverse events occurred in 25 (12%) women and CAD was present in 34 (16%). In receiver-operator characteristic (ROC) analysis for CAD detection, the average area under the curve (AUC) for DICE vs. Original status was 0.77±0.03 vs. 0.70±0.03, P<0.01. Similarly, in Kaplan-Meier survival analysis the average log-rank statistic was higher for DICE vs. the Original readings (10.6±5.2 vs. 3.0±0.6, P<0.05).

CONCLUSIONS

While two data sets are required to generate the DICE models no knowledge of follow-up results is needed. DICE modeling improved diagnostic and prognostic value vs. the Original interpretation of the myocardial perfusion status.

Withholding or continuing beta-blocker treatment before dipyridamole myocardial perfusion imaging for the diagnosis of coronary artery disease? A randomized clinical trial

BACKGROUND

Although it has been shown that acute beta-blocker administration may reduce the presence or severity of myocardial perfusion defects with dipyridamole stress, little information is available about the potential effect of chronic beta-blocker treatment on the sensitivity of dipyridamole myocardial perfusion imaging (DMPI).

METHODS

As a randomized clinical trial, one hundred twenty patients (103 male and 17 female) with angiographically confirmed CAD who were on long-term beta blocker therapy (≥3 months) enrolled in a randomized clinical trial study. The patients were allocated into two groups: Group A (n=60) in whom the beta-blocker agent was discontinued for 72h before DMPI and Group B (n=60) without discontinuation of beta-blockers prior to DMPI.

RESULTS

No significant difference was noted between the groups concerning age, sex, type of the injected radiotracer and number of involved coronary vessels. The mean rank of total perfusion scores for whole myocardium (irrespective of reversibility or irreversibility) in group B was not significantly different from that of group A, (65.75 vs. 55.25, P=0.096). Regarding the only irreversible perfusion defects, the mean rank of perfusion score in group B was higher than that of group A for whole myocardium (72 vs. 49, P=0.0001); however, no difference was noted between two groups for only reversible perfusion defects (61.0 vs. 60.0, P=0.898). The overall sensitivity of DMPI for the diagnosis of CAD in group A (91.7%) was not statistically different from group B (90%).

CONCLUSION

Beta-blocker withholding before DMPI did not generally affect the sensitivity of the test for the diagnostic purposes in our study. Thus, beta-blocker withdrawal for just the purpose of diagnostic imaging is not mandatory particularly when medication discontinuation may cause the patients to face increased risk of heart events.

Cardiac PET/CT misregistration causes significant changes in estimated myocardial blood flow

Misregistration of cardiac PET/CT data can lead to misinterpretation of regional myocardial perfusion. However, the effect of misregistration on the quantification of myocardial blood flow (MBF) has not been studied.

METHODS

Cardiac (82)Rb-PET/CT scans of 10 patients with normal regional myocardial perfusion were analyzed. Realignment was done for the baseline and stress PET/CT images as necessary, and MBF was obtained from dynamic data. Then, the stress images were misregistered by 5 mm along the x-axis (left) and z-axis (cranial) and again by 10 mm. A 10-mm misregistration in the opposite direction (-10 mm along the x-axis [right] and z-axis [caudal]) was also tested. Stress MBF was recalculated for 5-, 10-, and -10-mm misregistrations.

RESULTS

Stress MBF of the left ventricle decreased by 10% ± 6% (P = 0.005) after 5-mm misregistration and by 24% ± 15% (P = 0.001) after 10-mm misregistration. In descending order, the most important stress MBF changes occurred in the anterior (39% ± 9%), lateral (34% ± 9%), apical (20% ± 16%), inferior (12% ± 10%), and septal (10% ± 12%) walls after 10-mm misregistration. Lesser changes were observed after 5-mm misregistration, with the same wall distribution. In contrast, -10-mm misregistration increased global MBF by 9% ± 6% (P = 0.004). In descending order, the overestimation of estimated MBF after -10-mm misregistration occurred in the lateral (15% ± 8%), apical (15% ± 18%), anterior (9% ± 5%), and inferior (9% ± 11%) walls.

CONCLUSION

Misregistration of the stress PET/CT dataset leads to significant global and regional artifactual alterations in the estimated MBF. Quantitative error was observed throughout the myocardium and was not confined to those heart regions that extended into the lung on misregistered CT.

Higher events rate in patients with a normal gated myocardial perfusion imaging with dipyridamole than exercise: "Run for reliability"

OBJECTIVE

The aim of this is to evaluate the negative predictive value (NPV) of a normal gated myocardial perfusion imaging (NGMPI) with exercise and dipyridamole in a propensity matched population.

MATERIALS AND METHODS

This is a prospective study conducted at Nuclear Cardiology Department of Karachi Institute of Heart Diseases, Karachi from December 2008 until June 2010. A total of 809 patients with a NGMPI with adequate exercise (558/809) or dipyridamole (251/809) stress were included and followed-up for 12-30 months (mean 24 ± 3 months) for fatal or non-fatal myocardial infarctions (MI).

RESULTS

Mean ejection fraction (%), end diastolic volume (ml), and end systolic volume (ml) in exercise and dipyridamole cohorts were (72 ± 08, 66 ± 11), (68 ± 13, 81 ± 17), and (19 ± 11, 26 ± 12) respectively. On follow-up, in dipyridamole cohort 2 fatal and 6 non-fatal MIs were reported. While in exercise cohort only 2 non-fatal MIs were reported. The NPV of a NGMPI with exercise was 99.7% (95% confidence interval [CI] 98.93-99.96%) with an event rate of 0.3% (95% CI; 0.03-0.6%) and annualized event rate of 0.15%. The NPV of NGMPI with dipyridamole was 96.80% (95% CI; 2.2-4.3%) with an event rate of 3.2% (95% CI; 1.39-3.83%) and annualized event rate of approximately 1.6%. Event free survival for dipyridamole group was significantly lower than exercise analyzed by Log-rank test (14.509, P < 0.001).

CONCLUSION

A NGMPI with dipyridamole stress has higher event rate (low-NPV) as compared with exercise and this raises concern over its credibility to label these patients into low-risk group.

A comparison of reconstruction and viewing parameters on image quality and accuracy of stress myocardial CT perfusion

BACKGROUND

Myocardial stress computed tomography perfusion (CTP) has similar diagnostic accuracy for detecting perfusion defects (PDs) versus single-photon emission computed tomography (SPECT). However, the optimal diagnostic viewing and image processing parameters for CTP are unknown.

OBJECTIVE

We sought to compare the diagnostic accuracy of different image processing techniques, cardiac phases, slice thicknesses, and viewing parameters for detection of PDs.

METHODS

A stress and rest dual-source CTP protocol was performed with adenosine. Twelve subjects with severe stenosis proven by quantitative coronary angiography (QCA), with corresponding territorial defects at SPECT, were selected as well as 7 controls (subjects with similar clinical suspicion but negative QCA and SPECT). Short-axis stress images were processed with 3 techniques: minimum intensity projection (MinIP), maximum intensity projection, and average intensity multiplanar reconstruction (MPR), 3 thicknesses (1, 3, 8 mm), and 2 phases (systolic, mid-diastolic). The resulting images (n = 1026) were randomized and interpreted by independent readers.

RESULTS

Diastolic reconstructions (8-mm MPR) showed the highest sensitivity (81%) to detect true PDs. The highest accuracy was achieved with the 8-mm (61%) and 1-mm (61%) MPR diastolic images. The most sensitive and accurate systolic reconstructions were 3-mm MinIP images. These findings related to viewing in relatively narrow window width and window level settings.

CONCLUSION

Viewing parameters for optimal accuracy in detection of perfusion defects on CTP differ for systolic and diastolic images.

Coronary risk assessment and management options in chronic kidney disease patients prior to kidney transplantation

Cardiovascular disease remains the most important cause of morbidity and mortality among kidney transplant recipients. Nearly half the deaths in transplanted patients are attributed to cardiac causes and almost 5% of these deaths occur within the first year after transplantation. The ideal strategies to screen for coronary artery disease (CAD) in chronic kidney disease patients who are evaluated for kidney transplantation (KT) remain controversial. The American Society of Transplantation recommends that patients with diabetes, prior history of ischemic heart disease or an abnormal ECG, or age ≥50 years should be considered as high-risk for CAD and referred for a cardiac stress test and only those with a positive stress test, for coronary angiography. Despite these recommendations, vast variations exist in the way these patients are screened for CAD at different transplant centers. The sensitivity and specificity of noninvasive cardiac tests in CKD patients is much lower than that in the general population. This has prompted the use of direct diagnostic cardiac catheterization in high-risk patients in several transplant centers despite the risks associated with this invasive procedure. No large randomized controlled trials exist to date that address these issues. In this article, we review the existing literature with regards to the available data on cardiovascular risk screening and management options in CKD patients presenting for kidney transplantation and outline a strategy for approach to these patients.

Addition of atropine to submaximal exercise stress testing in patients evaluated for suspected ischaemia with SPECT imaging: a randomized, placebo-controlled trial

PURPOSE

To evaluate the effects of the addition of atropine to exercise testing in patients who failed to achieve their target heart rate (HR) during stress myocardial perfusion imaging with single-photon emission computed tomography (SPECT).

METHODS

The study was a prospective, randomized, placebo-controlled design. Patients with suspected or known coronary artery disease who failed to achieve a target HR (≥85% of maximal predicted HR) during exercise SPECT imaging were randomized to receive intravenous atropine (n=100) or placebo (n=101).

RESULTS

The two groups of patients did not differ with respect to demographic or clinical characteristics. A higher proportion of patients in the atropine group achieved the target HR compared to the placebo group (60% versus 3%, p<0.0001). SPECT imaging was abnormal in a higher proportion of patients in the atropine group as compared to the placebo group (57% versus 42%, p<0.05). Stress-induced myocardial ischaemia was present in more patients in the atropine group as compared to placebo (47% versus 29%, p<0.01). In both groups of patients, no major side effects occurred.

CONCLUSION

The addition of atropine at the end of exercise testing is more effective than placebo in raising HR to adequate levels, without additional risks of complications. The use of atropine in patients who initially failed to achieve their maximal predicted HR is associated with a higher probability of achieving a diagnostic myocardial perfusion study.

Comparison of long-term mortality risk following normal exercise vs adenosine myocardial perfusion SPECT

BACKGROUND

A higher frequency of clinical events has been observed in patients undergoing pharmacological vs exercise myocardial perfusion single-photon emission computed tomography (SPECT). While this difference is attributed to greater age and co-morbidities, it is not known whether these tests also differ in prognostic ability among patients with similar clinical profiles.

METHODS AND RESULTS

We assessed all-cause mortality rates in 6,069 patients, followed for 10.2 ± 1.7 years after undergoing exercise or adenosine SPECT. We employed propensity analysis to match exercise and adenosine subgroups by age, gender, symptoms, and coronary risk factors. Within our propensity-matched cohorts, adenosine patients had an annualized mortality rate event rates that was more than twice that of exercise patients (3.9% vs 1.6%, P < .0001). Differences in mortality persisted among age groups, including those <55 years old. In the exercise cohort, mortality was inversely related to exercise duration, with comparable mortality noted for patients exercising <3 min and those undergoing adenosine testing.

CONCLUSIONS

Among patients with normal stress SPECT tests, those undergoing adenosine testing manifest a mortality rate that is substantially higher than that observed among adequately exercising patients, but comparable to that observed among very poorly exercising patients. This elevated risk underscores an important challenge for managing patients undergoing pharmacological stress testing.

Quantitative and qualitative analysis and interpretation of CT perfusion imaging

Coronary artery disease (CAD) remains the leading cause of death in the United States. Rest and stress myocardial perfusion imaging has an important role in the non-invasive risk stratification of patients with CAD. However, diagnostic accuracies have been limited, which has led to the development of several myocardial perfusion imaging techniques. Among them, myocardial computed tomography perfusion imaging (CTP) is especially interesting as it has the unique capability of providing anatomic- as well as coronary stenosis-related functional data when combined with computed tomography angiography (CTA). The primary aim of this article is to review the qualitative, semi-quantitative, and quantitative analysis approaches to CTP imaging. In doing so, we will describe the image data required for each analysis and discuss the advantages and disadvantages of each approach.

Comparison of dobutamine stress echocardiography, dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging in patients with end-stage renal disease

OBJECTIVES

We sought to assess and compare the diagnostic accuracy and prognostic value of dobutamine stress echocardiography (DSE), dobutamine SPECT, and adenosine SPECT myocardial perfusion imaging (MPI) in patients with end-stage renal disease (ESRD).

BACKGROUND

The optimal stress imaging modality for patients with ESRD has not yet been determined.

METHODS

Forty-nine patients with ESRD underwent DSE, dobutamine SPECT MPI, and adenosine SPECT MPI. The primary endpoint of the trial was concordance between stress tests with respect to the presence or absence of ischemia.

RESULTS

Agreement on the presence or absence of ischemia between adenosine SPECT MPI and DSE was 69% (kappa = .25, P = NS). Agreement on the presence or absence of ischemia between adenosine and dobutamine SPECT MPI was 77% (kappa = .37, P = <.009). Summed stress scores for adenosine and dobutamine SPECT MPI studies were highly correlated (r = .9, P = <.0001). DSE and SPECT MPI results provided incremental prognostic information when added to clinical variables.

CONCLUSIONS

There is moderate concordance between DSE and adenosine SPECT MPI in ESRD patients referred for stress testing. Interobserver agreement was higher for SPECT MPI compared to DSE. Based on these observations, the optimal approach for diagnosing severe coronary artery disease and assessing risk in patients with ESRD has yet to be determined, but appears to warrant further investigation.

Value of cardiovascular magnetic resonance stress perfusion testing for the detection of coronary artery disease in women

OBJECTIVES

We wanted to assess the value of cardiovascular magnetic resonance (CMR) stress testing for evaluation of women with suspected coronary artery disease (CAD).

BACKGROUND

A combined perfusion and infarction CMR examination can accurately diagnose CAD in the clinical setting in a mixed gender population.

METHODS

We prospectively enrolled 147 consecutive women with chest pain or other symptoms suggestive of CAD at 2 centers (Duke University Medical Center, Robert-Bosch-Krankenhaus). Each patient underwent a comprehensive clinical evaluation, a CMR stress test consisting of cine rest function, adenosine-stress and rest perfusion, and delayed-enhancement CMR infarction imaging, and X-ray coronary angiography within 24 h. The components of the CMR test were analyzed visually both in isolation and combined using a pre-specified algorithm. Coronary artery disease was defined as stenosis > or =70% on quantitative analysis of coronary angiography.

RESULTS

Cardiovascular magnetic resonance imaging was completed in 136 females (63.0 +/- 11.1 years), 37 (27%) women had CAD on coronary angiography. The combined CMR stress test had a sensitivity, specificity, and accuracy of 84%, 88%, and 87%, respectively, for the diagnosis of CAD. Diagnostic accuracy was high at both sites (Duke University Medical Center 82%, Robert-Bosch-Krankenhaus 90%; p = 0.18). The accuracy for the detection of CAD was reduced when intermediate grade stenoses were included (82% vs. 87%; p = 0.01 compared the cutoff of stenosis > or =50% vs. > or =70%). The sensitivity was lower in women with single-vessel disease (71% vs. 100%; p = 0.06 compared with multivessel disease) and small left ventricular mass (69% vs. 95%; p = 0.04 for left ventricular mass < or =97 g vs. >97 g). The latter difference was even more significant after accounting for end-diastolic volumes (70% vs. 100%; p = 0.02 for left ventricular mass indexed to end-diastolic volume < or =1.15 g/ml vs. >1.15 g/ml).

CONCLUSIONS

A multicomponent CMR stress test can accurately diagnose CAD in women. Detection of CAD in women with intermediate grade stenosis, single-vessel disease, and with small hearts is challenging.

The effect of beta-blockers on the diagnostic accuracy of vasodilator pharmacologic SPECT myocardial perfusion imaging

BACKGROUND

The effect of beta (beta) blockers on the accuracy, particularly the sensitivity, of vasodilator radionuclide myocardial perfusion imaging (MPI) is not entirely clear. This study aimed to further assess the effect of beta-blockers on the ability of MPI to identify significant and high-risk coronary artery disease (CAD).

METHODS AND RESULTS

For 555 patients who underwent vasodilator MPI and had coronary angiography within 90 days, global and per-vessel sensitivities and specificities were calculated, and were found to be similar between patients taking beta-blockers and those who were not. beta-blockers did not decrease the ability to detect patients with multivessel disease. Summed stress scores and summed rest scores were likewise similar in both groups. To account in part for catheterization referral bias and the potential of false-negative MPI studies in patients receiving beta-blockers, survival analysis was performed on 2646 patients with normal MPI studies who did not undergo cardiac catheterization and failed to demonstrate significant mortality difference related to the taking of beta-blockers.

CONCLUSIONS

beta-blocker therapy does not diminish the ability of vasodilator stress MPI to detect clinically significant CAD, nor hide the mortality risk of patients with normal studies not referred for catheterization.

Baseline serum levels of cardiac biomarkers in patients with stable coronary artery disease

Stable coronary artery disease (CAD) can cause repetitive reversible myocardial ischaemia, and it seems to be possible that reversibly injured myocardium releases small amounts of soluble cytoplasmic proteins. Hence, the aim was to evaluate the effect of stable CAD on baseline serum levels of cardiac biomarkers. We studied 68 consecutive outpatients referred for gated myocardial perfusion imaging. Before a treadmill exercise test, blood samples for measurement of creatine kinase (CK), CK-myocardial band (CK-MB) mass, myoglobin, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were collected. Normal perfusion patterns were detected in 29 (43%) patients (group 1) and perfusion defects were detected in 39 (57%) patients (group 2). Baseline serum levels of biomarkers except CK were significantly higher in group 2 (p=0.001). Stable CAD increases baseline levels of CK-MB mass, myoglobin, AST and LDH in the serum and this increase is related to the extent and severity of the perfusion defect and to some extent the ejection fraction of the left ventricle.

The prognostic value of Doppler echocardiographic-derived coronary flow reserve is not affected by concomitant antiischemic therapy at the time of testing

BACKGROUND

When wall motion abnormality is the diagnostic end point, concomitant antiischemic therapy heavily modulates the prognostic value of dipyridamole echocardiography test (DET). A negative test result is less benign, and a positive test result is more malignant if performed under therapy. Recently, coronary flow reserve (CFR) was added to wall motion in dual imaging DET. The aim of the study was to determine whether antianginal medications affect the prognostic value of Doppler echocardiographic-derived CFR in patients with known or suspected coronary artery disease undergoing DET.

METHODS

In a prospective, multicenter, observational study, we evaluated 1,779 patients (1,072 males; 64 +/- 11 years) who underwent high-dose dipyridamole (0.84 mg/kg for 6 minutes) stress echo with CFR evaluation of left anterior descending (LAD) artery by Doppler.

RESULTS

Seven hundred thirty-three (41%) patients were on antiischemic therapy at time of testing (nitrates and/or calcium antagonists and/or beta-blockers). Mean CFR was 2.3. +/- 0.6. At individual patient analysis, 1,141 patients had normal (CFR >2.0) and 638 had abnormal (CFR <or=2.0) CFR on LAD. During a median follow-up of 36 months, 263 events occurred as follows: 36 deaths and 59 ST-elevation myocardial infarctions (STEMIs) and 168 non-STEMIs (NSTEMIs). Survival was highest in patients with normal CFR and lowest in patients with abnormal CFR (87% vs 34%, P = .0001). Survival was comparable in patients with normal CFR on and off therapy and in patients with abnormal CFR on and off therapy. At multivariable analysis, hypertension (hazard ratio [HR] 1.5, 95% CI 1.0-1.9, P = .010), DET positivity for regional wall motion abnormalities (HR 5.7, 95% CI 4.3-7.4, P = .000), an abnormal CFR on LAD (HR 3.3, 95% CI 2.5-4.4, P = .000) were independent prognostic predictors of hard cardiac events.

CONCLUSION

Ongoing antiischemic therapy at the time of testing does not modulate the prognostic value of Doppler echocardiographic-derived coronary flow reserve.

Direct comparison between pharmacological stress with adenosine triphosphate disodium and exercise stress myocardial perfusion imagings

To clarify the significance of adenosine triphosphate disodium stress myocardial perfusion imaging (ATP-MPI), we directly compared the findings of ATP-MPI with those of exercise stress myocardial perfusion imaging (Ex-MPI). ATP-MPI, Ex-MPI, and coronary angiography (CAG) were performed within 60 days in 17 coronary artery disease patients with mean age of 62.1+/-7.9 years. CAG revealed single-vessel disease (SVD) in 10 patients and multivessel disease (MVD) in seven patients. The summed stress score (SSS) of ATP-MPI was significantly higher than that of Ex-MPI (10.0 [7.8-14.3] vs. 8.0 [4-18], P<0.05). No difference in the SSS was observed between ATP-MPI and Ex-MPI in patients with SVD (8.0 [6.0-9.0] vs. 8.0 [6.0-10.0], NS), whereas this difference was significant in patients with MVD (15.0 [14.0-22.8] vs.9 [7.3-16.3], P<0.05). There was no difference in the summed rest score between ATP-MPI and Ex-MPI. The univariate logistic analysis showed that "MVD" was the significant factor influencing to the overt discrepancy between ATP-MPI and Ex-MPI (odds ratio: 9.0, 95% confidence interval: 1.07-75.84, P=0.043). The accuracy of ATP-MPI and Ex-MPI in detecting the territory of stenotic coronary vessel or previous myocardial infarction was 98.0% and 92.1% (NS), respectively. In conclusion, ATP-MPI is useful for detecting potential ischemic areas that cannot be detected by Ex-MPI, particularly in patients with MVD.

Does beta blocker therapy affect the diagnostic accuracy of adenosine single-photon-emission computed tomographic myocardial perfusion imaging?

We retrospectively evaluated perfusion defect presence, extent, and severity in 158 consecutive patients receiving beta blockers, who underwent adenosine single-photon-emission computed tomography (SPECT) myocardial perfusion imaging (MPI) and coronary angiography. Seventy-six patients (group 1) had their beta blockers withdrawn 48 hours prior to testing, and 82 patients (group 2) remained on the beta blocker regimen. Groups 1 and 2 were similar in gender, age, pretest symptoms, and history of coronary artery disease (CAD). Group 1 patients had higher resting heart rates (79 +/- 19/min versus 68 +/- 13/min; P < 0.001), peak heart rates (91 +/- 21/min versus 80 +/- 15/min; P < 0.001), resting diastolic blood pressures (82 +/- 14 mm Hg versus 74 +/- 13 mm Hg; P < 0.001), peak systolic blood pressures (139 +/- 23 mm Hg versus 124 +/- 23 mm Hg; P < 0.001), and peak diastolic blood pressures (72 +/- 12 mm Hg versus 68 +/- 11 mm Hg; P = 0.04) than group 2 patients. Group 1 also had a higher incidence of angina during the 48 hours off beta blockers than group 2 (10% versus 2%; P < 0.001). There was no significant difference between the two groups in symptoms and side effects during adenosine infusion, quantitated lung/heart ratio, visually assessed lung uptake, transient ischemic dilation, post-stress ejection fraction, summed stress score, summed rest score, and summed difference score. In conclusion, in patients with CAD, beta blocker therapy does not affect the extent, severity, and reversibility of perfusion defects on adenosine SPECT MPI.

Influence of chronic renal failure on the heart rate response to dipyridamole in patients undergoing myocardial perfusion SPECT

BACKGROUND

Dipyridamole promotes a reduction in blood pressure and an increase in heart rate (HR), considered the normal hemodynamic response to the drug. Data suggest that patients with chronic renal failure (CRF) have an attenuation of this hemodynamic response. This study sought to evaluate the HR response to dipyridamole and its determinants in patients with or without CRF undergoing gated myocardial perfusion single photon emission computed tomography.

METHODS AND RESULTS

Consecutive patients (n = 355, 9.6% with CRF) undergoing rest/dipyridamole myocardial perfusion single photon emission computed tomography were evaluated. The HR response to dipyridamole was considered to be reduced if the HR ratio (maximal HR/rest HR) was 1.20 or less. A logistic regression analysis determined independent predictors of a blunted HR response. A reduced HR response was found in 84.4% of patients with CRF and 40.6% of those without CRF (P < .0001). In patients without CRF the independent predictors of abnormal HR response were hypertension, rest and differential perfusion scores, and left ventricular ejection fraction. In contrast, in CRF patients there was no significant association of any of the studied variables with abnormal HR response.

CONCLUSIONS

An abnormal HR response to dipyridamole is frequently found in patients with CRF. Different mechanisms may account for abnormal HR response in patients with or without CRF.

Symptom-limited exercise combined with dipyridamole stress: prognostic value in assessment of known or suspected coronary artery disease by use of gated SPECT imaging

BACKGROUND

Combining vasodilator and exercise stress reduces noncardiac side effects, improves image quality, and enhances the detection of ischemia, compared with suboptimal exercise or vasodilator stress alone. However, prognostic data with combined protocols are limited.

METHODS AND RESULTS

Consecutive patients (n = 2064) who underwent symptom-limited exercise and dipyridamole stress with gated single-photon emission computed tomography (SPECT) imaging, without early revascularization, were studied. Subsequent cardiac death or nonfatal myocardial infarction was related to exercise and gated SPECT variables. Cox proportional hazards regression modeling was performed to identify predictors of adverse outcome. Annualized event rates in patients with normal and abnormal images were 0.96% and 2.71%, respectively (P < .001). With abnormal imaging, annualized event rates were 0.86% and 3.13% in patients with average to high and fair or poor functional capacity, respectively (P = .019). Abnormal imaging, a severely reduced post-stress ejection fraction, transient ischemic dilation, and fair or poor functional capacity emerged as predictors of adverse outcome. Accordingly, patients were stratified into low-risk, intermediate-risk, and high-risk cohorts with annualized event rates of 0.94%, 2.24%, and 8.19%, respectively (P < .001 in any two-way comparison).

CONCLUSIONS

A protocol that combines symptom-limited exercise and dipyridamole stress with gated SPECT imaging provides highly effective risk stratification for adverse outcomes.

Clinical decision making with contemporary cardiovascular imaging: ischemic heart disease

Treating ischemic heart disease requires an understanding of both coronary artery anatomy as well as myocardial physiology. The following clinical vignette illustrates these complementary concepts as part of an ongoing series on cardiovascular imaging in the Journal of Cardiovascular Medicine. This series seeks to present contemporary approaches to diagnosis and management in cardiovascular medicine that include state-of-the-art imaging techniques guided by bedside clinical assessment. Incorporating volumetric multidetector computed tomography and dynamic magnetic resonance imaging at various stages of this patient's care afforded timely myocardial characterization and coronary artery intervention.