Contributions of nuclear cardiology to diagnosis and prognosis of patients with coronary artery disease

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.

A deep learning-based automated diagnosis system for SPECT myocardial perfusion imaging

Images obtained from single-photon emission computed tomography for myocardial perfusion imaging (MPI SPECT) contain noises and artifacts, making cardiovascular disease diagnosis difficult. We developed a deep learning-based diagnosis support system using MPI SPECT images. Single-center datasets of MPI SPECT images (n = 5443) were obtained and labeled as healthy or coronary artery disease based on diagnosis reports. Three axes of four-dimensional datasets, resting, and stress conditions of three-dimensional reconstruction data, were reconstructed, and an AI model was trained to classify them. The trained convolutional neural network showed high performance [area under the curve (AUC) of the ROC curve: approximately 0.91; area under the recall precision curve: 0.87]. Additionally, using unsupervised learning and the Grad-CAM method, diseased lesions were successfully visualized. The AI-based automated diagnosis system had the highest performance (88%), followed by cardiologists with AI-guided diagnosis (80%) and cardiologists alone (65%). Furthermore, diagnosis time was shorter for AI-guided diagnosis (12 min) than for cardiologists alone (31 min). Our high-quality deep learning-based diagnosis support system may benefit cardiologists by improving diagnostic accuracy and reducing working hours.

Comparison of positional artifacts in myocardial perfusion imaging in supine and semi-reclining position using dedicated D-SPECT cardiac camera: validation using CT based attenuation correction

BACKGROUND

Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols.

METHODS

We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image.

RESULTS

In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments.

CONCLUSION

The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images.

Prognostic value of myocardial flow reserve derived by quantitative SPECT for patients with intermediate coronary stenoses

BACKGROUND

Functional assessment of myocardial ischemia is critical for patients with intermediate coronary stenosis. As the diagnosis performance of absolute quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) by single-photon emission tomography (SPECT) has been proven, its prognostic value in patients with intermediate coronary stenosis remains to be evaluated.

METHODS

Patients with one or more target lesions of ≥ 50% to ≤ 80% diameter stenoses on invasive coronary angiography were prospectively included in this study. All patients were scheduled for clinically indicated SPECT myocardial perfusion imaging (MPI) within 3 months and agreed to provide informed consent to participate in quantitative SPECT acquisitions to obtain MBF and MFR values. The primary endpoint was defined as a composite of the major adverse cardiac events (MACE): Cardiac death, myocardial infarction, late revascularization and heart failure or unstable angina-related rehospitalization.

RESULTS

One hundred and nineteen patients (mean age 57 ± 8 years, 62.2% men) were included in the analysis. The average lumen stenosis of patients was 67.0 ± 10.4%. Over a median follow-up duration of 1408 days (interquartile range 1297-1666 days), 18 patients (15.1%) had MACE. Patients with impaired MFR (MFR < 2) had a significantly higher incidence of events than those with preserved MFR (MFR ≥ 2) in Kaplan-Meier survival analysis (Log-rank = 8.105, P = 0.004), while no significant difference was found between patients with normal relative perfusion and those with relative perfusion abnormalities (log-rank = 0.098, P > 0.05). In a multivariate Cox hazards analysis, the SPECT-derived MFR remained an independent predictor of MACE (HR 0.352, 95% CI 0.145-0.854, P = 0.021).

CONCLUSIONS

In a cohort of patients with angiographic intermediate coronary lesions, SPECT-derived MFR was an independent predictor of prognosis.

Evaluation of the cardiac subvolume dose and myocardial perfusion in left breast cancer patients with postoperative radiotherapy: a prospective study

Adjuvant breast radiotherapy could reduce the risk of local recurrence. However, the radiation dose received by the heart also increases the risk of cardiotoxicity and causes consequential heart diseases. This prospective study aimed to evaluate more precisely cardiac subvolume doses and corresponding myocardial perfusion defects according to the American Heart Association (AHA)'s 20-segment model for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) interpretation for breast cancer after radiotherapy. The 61 female patients who underwent adjuvant radiotherapy following breast cancer surgery for left breast cancer were enrolled. SPECT MPI were performed before radiotherapy for baseline study, and 12 months after for follow-up. Enrolled patients were divided into two groups, new perfusion defect (NPD) and non new perfusion defect found (non-NPD) according to myocardial perfusion scale score. CT simulation data, radiation treatment planning, and SPECT MPI images were fused and registered. The left ventricle was divided into four rings, three territories, and 20 segments according to the AHA's 20-segment model of the LV. The doses between NPD and non-NPD groups were compared by the Mann-Whitney test. The patients were divided into two groups: NPD group (n = 28) and non-NPD group (n = 33). The mean heart dose was 3.14 Gy in the NPD group and 3.08 Gy in the non-NPD group. Mean LV doses were 4.84 Gy and 4.71 Gy, respectively. The radiation dose of the NPD group was higher than the non-NPD group in the 20 segments of LV. There was significant difference in segment 3 (p = 0.03). The study indicated that the radiation doses to 20 segments of LV in NPD were higher than those in non-NPD significantly at segment 3, and higher in other segments in general. In the bull's eye plot combining radiation dose and NPD area, we found that the new cardiac perfusion decline may exist even in the low radiation dose region.Trial registration: FEMH-IRB-101085-F. Registered 01/01/2013, https://clinicaltrials.gov/ct2/show/NCT01758419?cond=NCT01758419&draw=2&rank=1 .

Fractional flow reserve and non-hyperemic indices: Essential tools for percutaneous coronary interventions

Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact. Fractional flow reserve (FFR) received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis. FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy, deferring unnecessary procedures for lesions with a FFR > 0.8, improving patients' management and clinical outcome. Post intervention, an optimal FFR > 0.9 post stenting should be reached and > 0.8 post drug eluting balloons. Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89. They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated. FFR remains the gold standard reference for invasive assessment of ischemia. We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio. We conclude introducing a hybrid approach to intermediate lesions (DFR 0.85-0.95) potentially maximizing clinical decision from all measurements.

Synthesis and biological evaluation of [131I]iodocarvedilol as a potential radiopharmaceutical for heart imaging

The optimization of the radiolabeling yield of carvedilol with iodine-131 was described. Dependence of the labeling yield of [¹³¹I]iodocarvedilol on the concentration of carvedilol, chloramine-T content, pH of the reaction mixture and reaction time was studied in details. Carvedilol was labeled with iodine-131 at pH 6 with a labeling yield of 92.6 ± 2.77% by using 100 µg carvedilol, 200 µg chloramin-T (CAT) and 30 min reaction time. The formed [¹³¹I]iodocarvedilol was nearly stable for a time up to one day. Biodistribution of [¹³¹I]iodocarvedilol was investigated in experimental animals. [^131/123I]iodocarvedilol was located in the heart with a concentration of 19.6 ± 0.41% of the injected dose at 60 min post injection. It has a high heart uptake and heart to liver ratio, both of which are beneficial for high-quality SPECT (single-photon emission computerized tomography) myocardial imaging. [^131/123I]iodocarvedilol solve most the drawbacks of the FDA (Food and Drug Administration) approved ^99mTc-sestamibi.

Integration of quantitative absolute myocardial blood flow estimates from dynamic CZT-SPECT improves the detection of coronary artery disease

BACKGROUND

Balanced ischemia with multi-vessel coronary artery disease (CAD) is difficult to diagnose with semiquantitative single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Dynamic cardiac SPECT provides quantitative estimations of stenosis severity and ischemic burden by assessing myocardial flow reserve (MFR) and myocardial blood flow (MBF). The aim of this study was to evaluate the incremental value of dynamic SPECT in multi-vessel coronary artery disease (CAD).

METHODS

Patients with suspected CAD who underwent dynamic ECG-gated dipyridamole MPI and coronary angiography within 6 months were retrospectively reviewed. The performance of summed stress, rest and difference scores (SSS, SRS, SDS), post-stress and resting MBF (MBFs, MBFr) and MFR were compared at both patient level and vessel level.

RESULTS

In 32 patients with 39 stenotic vessels, 12 had three-vessel disease (38%). Globally increased SSS and impaired MBF values were significantly associated with significant CAD at the patient level, but SDS and MFR were not. Regional increases in SSS and reductions in both MBFs and MBFr were significantly associated with stenotic vessels. The best cutoff value of global MBFs to predict CAD was 3.5 ml·g-1·min-1 (area under the curve, AUC = .84, P = .002). The best cutoff value of regional MBFs to detect significant stenosis was 3.6 ml·g-1·min-1 (AUC = .74, P < .001). However, the best possible cut-off values of MFR were not found. Sex-difference in both global and regional MBFr but MBFs was found, which might result in the non-significance in MFR.

CONCLUSIONS

This study validated a clinically available method to quantify MFR using dynamic CZT-SPECT. This method improved the detectability of multi-vessel CAD, and absolute MBFs was superior to MFR and other semiquantitative MPI parameters.

Using real-world data to monitor and improve quality of care in coronary artery disease: results from the Netherlands Heart Registration

Worldwide, quality registries for cardiovascular diseases enable the use of real-world data to monitor and improve the quality of cardiac care. In the Netherlands Heart Registration (NHR), cardiologists and cardiothoracic surgeons register baseline, procedural and outcome data across all invasive cardiac interventional, electrophysiological and surgical procedures. This paper provides insight into the governance and processes as organised by the NHR in collaboration with the hospitals. To clarify the processes, examples are given from the percutaneous coronary intervention and coronary artery bypass grafting registries. Physicians who are mandated by their hospital to instruct the NHR to process their data are united in registration committees. The committees determine standard sets of variables and periodically discuss the completeness and quality of data and patient-relevant outcomes. In the case of significant variation in outcomes, processes of healthcare delivery are discussed and good practices are shared in a non-competitive and safe setting. To create new insights for further improvement in patient-relevant outcomes, quality projects are initiated on, for example, multivessel disease treatment, cardiogenic shock and diagnostic intracoronary procedures. Moreover, possibilities are explored to expand the quality registries through additional relevant indicators, such as resource use before and after the procedure, by enriching NHR data with other existing data resources.

A rapid electromechanical model to predict reverse remodeling following cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an effective therapy for patients who suffer from heart failure and ventricular dyssynchrony such as left bundle branch block (LBBB). When it works, it reverses adverse left ventricular (LV) remodeling and the progression of heart failure. However, CRT response rate is currently as low as 50-65%. In theory, CRT outcome could be improved by allowing clinicians to tailor the therapy through patient-specific lead locations, timing, and/or pacing protocol. However, this also presents a dilemma: there are far too many possible strategies to test during the implantation surgery. Computational models could address this dilemma by predicting remodeling outcomes for each patient before the surgery takes place. Therefore, the goal of this study was to develop a rapid computational model to predict reverse LV remodeling following CRT. We adapted our recently developed computational model of LV remodeling to simulate the mechanics of ventricular dyssynchrony and added a rapid electrical model to predict electrical activation timing. The model was calibrated to quantitatively match changes in hemodynamics and global and local LV wall mass from a canine study of LBBB and CRT. The calibrated model was used to investigate the influence of LV lead location and ischemia on CRT remodeling outcome. Our model results suggest that remodeling outcome varies with both lead location and ischemia location, and does not always correlate with short-term improvement in QRS duration. The results and time frame required to customize and run this model suggest promise for this approach in a clinical setting.

Verification of Coronary Computed Tomography-Derived Fractional Flow Reserve Measurement Site for Detection of Significant Coronary Artery Disease

Background: The optimal site for measuring computed tomography (CT)-derived fractional flow reserve (FFR_CT) to detect significant coronary artery disease (CAD) remains unknown. We investigated how diagnostic performance changes with FFR_CT measurement site. Methods and Results: The diagnostic performance of FFR_CT, measured 1-2 cm distal to the stenosis vs. a far-distal site, in detecting significant CAD with invasive fractional flow reserve ≤0.8 was evaluated in 254 diseased vessels from 146 patients with stable or suspected CAD diagnosed by coronary CT angiography. Receiver operating characteristic curve analysis revealed a significantly larger area under the curve for FFR_CT measured 1-2 cm distal to the stenosis than at a far-distal site (0.829 vs. 0.791, respectively; P=0.0305). The rate of reclassification of positive FFR_CT was 19% for measurements made 1-2 cm distal to the stenosis, and diagnostic accuracy for FFR_CT 0.71-0.80 improved from 36% to 58% (P=0.0052). Vessel-based diagnostic accuracy of FFR_CT 1-2 cm distal to the stenosis and at a far-distal site was 75% and 65%, respectively (P<0.0001), with corresponding sensitivity of 87% and 94% (P=0.0039), specificity of 60% and 29% (P<0.0001), a positive predictive value of 73% and 62% (P=0.028), and a negative predictive value of 78% and 79% (P=0.958). Conclusions: Our data suggest measuring FFR_CT 1-2 cm distal to the stenosis has better diagnostic performance for detecting physiologically significant CAD.

Motion in nuclear cardiology imaging: types, artifacts, detection and correction techniques

In this paper, the authors review the field of motion detection and correction in nuclear cardiology with single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging systems. We start with a brief overview of nuclear cardiology applications and description of SPECT and PET imaging systems, then explaining the different types of motion and their related artefacts. Moreover, we classify and describe various techniques for motion detection and correction, discussing their potential advantages including reference to metrics and tasks, particularly towards improvements in image quality and diagnostic performance. In addition, we emphasize limitations encountered in different motion detection and correction methods that may challenge routine clinical applications and diagnostic performance.

Cardiovascular event risk estimated by myocardial perfusion SPECT combined with clinical data

Myocardial scintigraphy plays important roles in the diagnosis of coronary artery disease, prognostic risk stratification, and determination of the treatment policy. Recently, several large-scale clinical trials reported that coronary intervention was not necessarily advantageous for preventing future cardiac events in patients with stable angina. This review summarizes how we can estimate cardiac event risks based on Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS), and describes that the combination of scintigraphy and other clinical features leads to more accurate stratification of prognosis and the determination of subsequent treatment policy.

Mechanical dyssynchrony: How do we measure it, what it means, and what we can do about it

Left ventricular mechanical dyssynchrony (LVMD) is defined by a difference in the timing of mechanical contraction or relaxation between different segments of the left ventricle (LV). Mechanical dyssynchrony is distinct from electrical dyssynchrony as measured by QRS duration and has been of increasing interest due to its association with worse prognosis and potential role in patient selection for cardiac resynchronization therapy (CRT). Although echocardiography is the most used modality to assess LVMD, some limitations apply to this modality. Compared to echo-based modalities, nuclear imaging by gated single-photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) has clear advantages in evaluating systolic and diastolic LVMD. GSPECT MPI can determine systolic and diastolic mechanical dyssynchrony by the variability in the timing in which different LV segments contract or relax, which has prognostic impact in patients with coronary artery disease and heart failure. As such, by targeting mechanical dyssynchrony instead of electrical dyssynchrony, GSPECT MPI can potentially improve patient selection for CRT. So far, few studies have investigated the role of diastolic dyssynchrony, but recent evidence seems to suggest high prevalence and more prognostic impact than previously recognized. In the present review, we provide an oversight of mechanical dyssynchrony.

Introduction to the D-SPECT for Technologists: Workflow Using a Dedicated Digital Cardiac Camera

The D-SPECT is a dedicated cardiac camera that incorporates a solid-state semiconductor detector. This camera differs greatly from conventional SPECT/CT systems, resulting in significant differences in patient imaging. This continuing education article focuses on the specifications of both SPECT/CT and D-SPECT systems, radiopharmaceutical dosing requirements, imaging workflows, and some disadvantages of using each camera system. When used properly, the D-SPECT system can provide high-quality cardiac images with lower doses and faster exam times than conventional SPECT/CT systems.

Physiology over Angiography to Determine Lesion Severity: the FAME Trials

The "Achilles heel" of invasive coronary angiography is its inability to accurately localize which stenoses induce ischemia and warrant treatment. Fractional flow reserve (FFR) is a coronary wire-based physiologic index that measures the functional significance of epicardial stenoses, thereby overcoming this limitation. Over the past decade, the landmark FAME (Fractional Flow Reserve vs Angiography for Multivessel Evaluation) trials demonstrated the clinical utility of an FFR-guided strategy for percutaneous coronary intervention (PCI) compared with angiography-only PCI or medical therapy alone in patients with predominantly stable ischemic heart disease. These trials have spurred the current era of coronary-physiology-guided revascularization.

The prognostic value of diastolic and systolic mechanical left ventricular dyssynchrony among patients with coronary artery disease and heart failure

BACKGROUND

Prevalence and prognostic value of diastolic and systolic dyssynchrony in patients with coronary artery disease (CAD) + heart failure (HF) or CAD alone are not well understood.

METHODS

We included patients with gated single-photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) between 2003 and 2009. Patients had at least one major epicardial obstruction ≥ 50%. We assessed the association between dyssynchrony and outcomes, including all-cause and cardiovascular death.

RESULTS

Of the 1294 patients, HF was present in 25%. Median follow-up was 6.7 years (IQR 4.9-9.3) years with 537 recorded deaths. Patients with CAD + HF had a higher incidence of dyssynchrony than patients with CAD alone (diastolic BW 28.8% for the HF + CAD vs 14.7% for the CAD alone). Patients with CAD + HF had a lower survival than CAD alone at 10 years (33%; 95% CI 27-40 vs 59; 95% CI 55-62, P < 0.0001). With one exception, HF was found to have no statistically significant interaction with dyssynchrony measures in unadjusted and adjusted survival models.

CONCLUSIONS

Patients with CAD + HF have a high prevalence of mechanical dyssynchrony as measured by GSPECT MPI, and a higher mortality than CAD alone. However, clinical outcomes associated with mechanical dyssynchrony did not differ in patients with and without HF.

Role of DECT in coronary artery disease: a comparative study with ICA and SPECT

PURPOSE

Earlier imaging techniques for coronary artery disease (CAD) focused primarily on either morphological or functional assessment of CAD. However, dual-energy computed tomography (DECT) can be used to assess myocardial blood supply both morphologically and functionally. We aimed to evaluate the diagnostic accuracy of DECT in detecting morphological and functional components of CAD, using invasive coronary angiography (ICA) and single photon emission computed tomography (SPECT) as reference standards.

METHODS

Twenty-five patients with known or suspicious CAD and scheduled for ICA were investigated by DECT and SPECT. DECT was performed during the resting state using retrospective electrocardiography (ECG) gating. CT coronary angiography and perfusion images were generated from the same raw data. All patients were evaluated for significant stenosis (≥50%) on both ICA and DECT coronary angiography, and for myocardial perfusion defects on SPECT and DECT perfusion. Comparison was done between ICA and DECT coronary angiography for detection of significant stenosis and between SPECT and DECT perfusion for detecting myocardial perfusion defects.

RESULTS

Using ICA as reference standard, sensitivity, specificity, and accuracy of DECT coronary angiography in detecting ≥50% stenosis of coronary artery lumen were 81.6%, 97.8%, and 95.0%, respectively, by segment-based analysis and 92.1%, 96.1%, and 93.7%, respectively, by vessel-based analysis. Using SPECT as the reference standard, the sensitivity, specificity, and accuracy of DECT perfusion in detecting myocardial perfusion defects were 70.4%, 86.4%, and 80.6%, respectively, on per-segment analysis and 90.7%, 66.6%, and 84.7%, respectively, on per-territorial basis.

CONCLUSION

DECT accurately detected coronary artery stenosis and myocardial ischemia using ICA and SPECT as reference standards. In the same scan, DECT can accurately provide integrative imaging of coronary artery morphology and myocardial perfusion.

[Comparison of the prognostic value of different clinical, angiographic and scintigraphic scores in stable coronary patients after acute coronary syndrome]

INTRODUCTION

To date, there is no consensus regarding the follow-up of asymptomatic coronary patients with an intermediate risk of events. Indeed, most of cardiovascular events (CVE) occur in asymptomatic patients, hence the clinician's interest in establishing risk stratification scores. In asymptomatic patient, the risk assessment after acute coronary syndrome (ACS) can currently be based on 3 types of score: clinical with, for example, the REACH score; angiographic with the residual SYNTAX score; imaging with different scintigraphic scores. These scores differ widely in terms of evaluation criteria and period of analysis. The aim of our study was therefore, in stable and asymptomatic coronary patients after ACS, to compare these different predictive scores; to establish that the combination of these scores makes it possible to optimize the risk assessment during the follow-up.

METHODS

Our retrospective study included 236 revascularized patients after ACS. Three different risk scores were collected: 1) the residual SYNTAX score, calculated at the time of revascularization; 2) the scintigraphic risk score described by Sharir et al., performed 3 to 12 months after the event and taking into account the extent of ischemia (SDS) and the poststress left ventricular ejection fraction (LVEF). Patients with LVEF <50% and/or moderate to severe ischemic disease (SDS≥2) were considered with an intermediate or high scintigraphic risk; 3) the REACH clinical score calculated on the day of the scintigraphic examination. After the myocardial scintigraphic exam, patients had a 1-year follow-up and CVE were recorded. Continuous data were analyzed either by Student's t-test or non-parametric Mann-Whitney test. The dichotomous data were compared either by the χ² test or by Fisher's exact test.

RESULTS

Forty-eight patients (20.1%) had a CVE during the 1-year follow-up. Thirty patients (13.8%) had a high residual SYNTAX score (≥8) without any correlation observed between the residual SYNTAX score and CVE (P=0.359). 148 patients (57.7%) had a high REACH clinical score (≥11) with no significant correlation observed with CVE (P=0.079). Lastly, 34 patients (14.4%) had an intermediate or high scintigraphic score, this imaging score being strongly correlated with a greater number of CVE (P<0.001). Multivariate analysis revealed 3 independent factors associated with CVE: a scintigraphic score> 2 (OR [(95% CI): 5.530 [2.426-12.605] P<0.001); Peripheral Arterial Obstructive Disease (PAOD) (OR [95% CI]: 8.531 [2.540-28.660] P<0.001); diabetes (OR [95% CI]: 2.86 [1.262-6.517] P=0,012).

CONCLUSION

The combination of the scintigraphic score with two clinical factors, such as PAOD and diabetes, provides optimal prognostic value in the evaluation of asymptomatic and stable patients after ACS. Our study therefore highlights the importance of optimizing evaluation strategies in the follow-up of these patients who remain at risk of post-revascularization CVE.

Diagnostic Accuracy of Perfusional Computed Tomography in Moderate Coronary Stenosis: Comparison With Fractional Flow Reserve

Coronary computed tomography with myocardial perfusion imaging (CCTA-MPI) provides data on coronary anatomy and perfusion and may be useful in the assessment of ischemic coronary artery disease (CAD). Management of angiographically intermediate coronary lesions is challenging, and coronary fractional flow reserve (FFR) evaluation is recommended to assess whether these lesions are functionally significant. Our aim was to evaluate the diagnostic accuracy of CCTA-MPI in patients with stable CAD and at least 1 angiographically intermediate coronary lesion submitted to FFR. In this single-center prospective study, patients with stable CAD and at least 1 moderate coronary stenosis (50%-70% by visual estimation) were referred for CCTA-MPI (64-row multidetector) assessment before coronary FFR evaluation. Patients with severe coronary obstructions (≥70%) were excluded. The significance level adopted for all tests was 5%. Twenty-eight patients (mean age 60 ± SD years, 54% women) with 33 intermediate coronary obstructions were enrolled. Ten patients (30%) had functionally significant coronary obstructions characterized by FFR ≤0.8. The sensitivity, specificity, and accuracy of CCTA-MPI for the detection of functionally significant coronary obstructions were 30%, 100%, and 78.8%, respectively. CCTA-MPI positive predictive value was 100%, whereas negative predictive value was 76.7%. Correlation coefficient between tests was 0.48 (P = 0.005). On a novel approach to evaluate intermediate coronary lesions, accuracy of CCTA-MPI was 78.8%. The positive predictive value of an abnormal CCTA-MPI on this population was 100%, suggesting that CCTA-MPI may have a role in the assessment of patients with anatomically identified intermediate coronary lesions.

Application of the DILEMMA score to improve lesion selection for invasive physiological assessment

OBJECTIVES

We sought to assess the validity of the DILEMMA score against instantaneous wave-free ratio (iFR) and evaluate its utility in rationalizing the number of patients referred for invasive physiological assessment.

BACKGROUND

The DILEMMA score is a validated angiographic scoring tool incorporating minimal lumen diameter, lesion length and subtended myocardial area that has been shown to predict the functional significance of lesions as assessed by fractional flow reserve (FFR).

METHODS

Patients in the DEFINE-FLAIR study who had coronary stenosis of intermediate severity were randomized to either FFR or iFR. DILEMMA score was calculated retrospectively on a subset of this cohort by operators blinded to FFR or iFR values.

RESULTS

Three hundred and forty-six lesions (181 assessed by FFR; 165 by iFR) from 259 patients (mean age 66.0 years, 79% male) were included. A DILEMMA score ≤ 2 had a negative predictive value of 96.3% and 95.7% for identifying lesions with FFR >0.80 and iFR >0.89, respectively. A DILEMMA score ≥ 9 had a positive predictive value of 88.9% and 100% for identifying lesions with FFR ≤0.80 and iFR ≤0.89, respectively. The receiver operating characteristic area under the curve values for DILEMMA score to predict FFR ≤0.80 and iFR ≤0.89 were 0.83 (95% CI 0.77-0.90) and 0.82 (0.75-0.89) respectively. A DILEMMA score ≤ 2 or ≥9 occurred in 172 of the 346 lesions (49.7%).

CONCLUSIONS

Using DILEMMA score in patients with coronary stenosis of intermediate severity may reduce the need for pressure wire use, offering potential cost-savings and minimizing the risks associated with invasive physiological lesion assessment.

A combined static-dynamic single-dose imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT

BACKGROUND

SPECT myocardial perfusion imaging (MPI) is a clinical mainstay that is typically performed with static imaging protocols and visually or semi-quantitatively assessed for perfusion defects based upon the relative intensity of myocardial regions. Dynamic cardiac SPECT presents a new imaging technique based on time-varying information of radiotracer distribution, which permits the evaluation of regional myocardial blood flow (MBF) and coronary flow reserve (CFR). In this work, a preliminary feasibility study was conducted in a small patient sample designed to implement a unique combined static-dynamic single-dose one-day visit imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT for improving the diagnosis of coronary artery disease (CAD).

METHODS

Fifteen patients (11 males, four females, mean age 71 ± 9 years) were enrolled for a combined dynamic and static SPECT (Infinia Hawkeye 4, GE Healthcare) imaging protocol with a single dose of 99mTc-tetrofosmin administered at rest and a single dose administered at stress in a one-day visit. Out of 15 patients, eleven had selective coronary angiography (SCA), 8 within 6 months and the rest within 24 months of SPECT imaging, without intervening symptoms or interventions. The extent and severity of perfusion defects in each myocardial region was graded visually. Dynamically acquired data were also used to estimate the MBF and CFR. Both visually graded images and estimated CFR were tested against SCA as a reference to evaluate the validity of the methods.

RESULTS

Overall, conventional static SPECT was normal in ten patients and abnormal in five patients, dynamic SPECT was normal in 12 patients and abnormal in three patients, and CFR from dynamic SPECT was normal in nine patients and abnormal in six patients. Among those 11 patients with SCA, conventional SPECT was normal in 5, 3 with documented CAD on SCA with an overall accuracy of 64%, sensitivity of 40% and specificity of 83%. Dynamic SPECT image analysis also produced a similar accuracy, sensitivity, and specificity. CFR was normal in 6, each with CAD on SCA with an overall accuracy of 91%, sensitivity of 80%, and specificity of 100%. The mean CFR was significantly lower for SCA detected abnormal than for normal patients (3.86±1.06 vs 1.94±0. 0.67, P < 0.001).

CONCLUSIONS

The visually assessed image findings in static and dynamic SPECT are subjective, and may not reflect direct physiologic measures of coronary lesion based on SCA. The CFR measured with dynamic SPECT is fully objective, with better sensitivity and specificity, available only with the data generated from the dynamic SPECT method.

Automated Quantitative Stress Perfusion in a Clinical Routine

Cardiovascular magnetic resonance (CMR) perfusion imaging is a robust noninvasive technique to evaluate ischemia in patients with coronary artery disease (CAD). Although qualitative and semiquantitative methods have shown that CMR has high accuracy in diagnosing flow-obstructing lesions in CAD, quantitative ischemic burden is an important variable used in clinical practice for treatment decisions. Quantitative CMR perfusion techniques have evolved significantly, with accuracy comparable with both PET and microsphere evaluation. Routine clinical use of these quantitative techniques has been facilitated by the introduction of automated methods that accelerate the work flow and rapidly generate pixel-based myocardial blood flow maps.

Clinical performance of Rb-82 myocardial perfusion PET and Tc-99m-based SPECT in patients with extreme obesity

BACKGROUND

We evaluated the performance of stress imaging with technetium-99m-labeled tetrofosmin single-photon emission computed tomography (SPECT) and rubidium-82 positron emission tomography (PET) in patients with extreme obesity, defined as body mass index ≥40 kg/m2.

METHODS

We identified patients with extreme obesity who underwent angiography in our center and either stress SPECT or PET within the previous six months. Cohorts of patients with extreme obesity and a <5% pretest likelihood of CAD who underwent SPECT (N = 25) or PET (N = 25) were also included.

RESULTS

In total, 108 patients who underwent SPECT (N = 57) or PET (N = 51) were identified. Scan interpretation was classified as definitely normal or abnormal in 83.3% of PET and 60.5% of SPECT scans, respectively (P < .01). PET demonstrated higher diagnostic accuracy and normalcy rate. PET was found to have higher specificity for the pooled cohort. Similar findings were observed using stenosis cut-offs of ≥50% and ≥70%.

CONCLUSIONS

In patients with extreme obesity, PET enabled more definitive scan interpretation with less artifact compared to SPECT. PET provided higher diagnostic accuracy and specificity in the detection of obstructive coronary artery disease.

IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report)

The IUPAC (International Union of Pure and Applied Chemistry) Periodic Table of the Elements and Isotopes (IPTEI) was created to familiarize students, teachers, and non-professionals with the existence and importance of isotopes of the chemical elements. The IPTEI is modeled on the familiar Periodic Table of the Chemical Elements. The IPTEI is intended to hang on the walls of chemistry laboratories and classrooms. Each cell of the IPTEI provides the chemical name, symbol, atomic number, and standard atomic weight of an element. Color-coded pie charts in each element cell display the stable isotopes and the relatively long-lived radioactive isotopes having characteristic terrestrial isotopic compositions that determine the standard atomic weight of each element. The background color scheme of cells categorizes the 118 elements into four groups: (1) white indicates the element has no standard atomic weight, (2) blue indicates the element has only one isotope that is used to determine its standard atomic weight, which is given as a single value with an uncertainty, (3) yellow indicates the element has two or more isotopes that are used to determine its standard atomic weight, which is given as a single value with an uncertainty, and (4) pink indicates the element has a well-documented variation in its atomic weight, and the standard atomic weight is expressed as an interval. An element-by-element review accompanies the IPTEI and includes a chart of all known stable and radioactive isotopes for each element. Practical applications of isotopic measurements and technologies are included for the following fields: forensic science, geochronology, Earth-system sciences, environmental science, and human health sciences, including medical diagnosis and treatment.

Network meta-analysis comparing iFR versus FFR versus coronary angiography to drive coronary revascularization

AIMS

Instantaneous free-wave ratio (iFR) has been recently demonstrated non-inferior to fractional flow reserve (FFR) to drive coronary revascularization; however, no study has compared iFR versus coronary angiography (CA). We performed a network meta-analysis to evaluate efficacy and safety of iFR- versus CA-guided strategy.

METHODS AND RESULTS

We searched for randomized trials and studies with propensity score matching in The Cochrane Collaboration Central Register of Controlled Trials, EMBASE, and MEDLINE/Pubmed. CA, FFR, and iFR were the three competitive arms, MACE (a composite endpoint of death, myocardial infarction [MI], and target vessel revascularization [TVR]) was the primary endpoint, while its single components the secondary ones. Subgroup analysis was performed for patients presenting with stable coronary artery disease. Eight studies were selected: 4126 patients were evaluated with FFR, 2160 with iFR, and 2214 with CA, acute coronary syndrome (ACS) was the most frequent admission diagnosis. After 12 months, rates of MACE and all-cause death did not differ between groups (respectively OR 1.04 and OR 0.86 for iFR vs FFR). Both FFR and iFR reduced TVR compared to CA (respectively OR 0.68 and OR 0.70). In patients with stable CAD both FFR and iFR reduced risk of subsequent MI compared to CA (respectively OR 0.66 and OR 0.79).

CONCLUSION

Compared to CA alone, both FFR and iFR are safe and effective in guiding coronary revascularization at 12 months. In patients with stable CAD, both FFR and iFR-guided revascularization reduce the risk of subsequent MI at 12 months.

Defining and Measuring a Standard Set of Patient-Relevant Outcomes in Coronary Artery Disease

Systematic outcome measurement enables to continuously improve treatment results and stimulates dissemination of best practices. For patients with coronary artery disease, no examples yet exist of standard sets of patient-relevant outcome measures that have already been fully implemented at a large scale in clinical care. The aim of this paper is twofold: (1) to share the standard set of outcome measures as developed by Meetbaar Beter, and (2) to show how the standard set is presented and published to support improvement of cardiac care. A step-wise approach was followed by an expert panel to construct a standard set of outcome measures. This resulted in a comprehensive set of relevant outcome measures, comprising 4 generic and 11 treatment-specific outcomes. Both short-term and long-term outcomes measures up to 5 years of follow-up were included. Relevant initial conditions were selected to enable case-mix adjustment. The standard set has been implemented in 21 hospitals across the Netherlands. The results and experiences have been used to fine-tune the set in 4 reporting cycles in 2012 to 2016, using an annual maintenance cycle. Currently about 83,000 percutaneous coronary interventions and 30,000 coronary artery bypass graftings are included in the dataset, covering the majority of all percutaneous coronary interventions and coronary artery bypass graftings in the Netherlands. In conclusion, Meetbaar Beter has defined and implemented a comprehensive set of patient-relevant outcome measures for coronary artery disease, and the variation of the results among the centers indicates that there are sufficient opportunities to further improve cardiac care in the Netherlands.

A comparison of cardiovascular magnetic resonance and single photon emission computed tomography (SPECT) perfusion imaging in left main stem or equivalent coronary artery disease: a CE-MARC substudy

BACKGROUND

Assessment of left main stem (LMS) stenosis has prognostic and therapeutic implications. Data on assessment of LMS disease by cardiovascular magnetic resonance (CMR) and single photon emission computed tomography (SPECT) are limited. CE-MARC is the largest prospective comparison of CMR and SPECT against quantitative invasive coronary angiography (QCA) for detection of coronary artery disease (CAD), and provided the framework for this evaluation. The aims of this study were to compare diagnostic accuracy of visual and quantitative perfusion CMR to SPECT in patients with LMS stable CAD.

METHODS

Fifty-four patients from the CE-MARC study were included: 27 (4%) with significant LMS or LMS-equivalent disease on QCA, and 27 age/sex-matched patients with no flow-limiting CAD. All patients underwent multi-parametric CMR, SPECT and QCA. Performance of visual and quantitative perfusion CMR by Fermi-constrained deconvolution to detect LMS disease was compared with SPECT.

RESULTS

Of 27 patients in the LMS group, 22 (81%) had abnormal CMR and 16 (59%) had abnormal SPECT. All patients with abnormal CMR had abnormal perfusion by visual analysis. CMR demonstrated significantly higher area under the curve (AUC) for detection of disease (0.95; 0.85-0.99) over SPECT (0.63; 0.49-0.76) (p = 0.0001). Global mean stress myocardial blood flow (MBF) by CMR in LMS patients was significantly lower than controls (1.77 ± 0.72 ml/g/min vs. 3.28 ± 1.20 ml/g/min, p < 0.001). MBF of <2.08 ml/g/min had sensitivity of 78% and specificity of 85% for diagnosis of LMS disease, with an AUC (0.87; 0.75-0.94) not significantly different to visual CMR analysis (p = 0.18), and more accurate than SPECT (p = 0.003).

CONCLUSION

Visual stress perfusion CMR had higher diagnostic accuracy than SPECT to detect LMS disease. Quantitative perfusion CMR had similar performance to visual CMR perfusion analysis.

Variable temporal sampling and tube current modulation for myocardial blood flow estimation from dose-reduced dynamic computed tomography

Quantification of myocardial blood flow (MBF) can aid in the diagnosis and treatment of coronary artery disease. However, there are no widely accepted clinical methods for estimating MBF. Dynamic cardiac perfusion computed tomography (CT) holds the promise of providing a quick and easy method to measure MBF quantitatively. However, the need for repeated scans can potentially result in a high patient radiation dose, limiting the clinical acceptance of this approach. In our previous work, we explored techniques to reduce the patient dose by either uniformly reducing the tube current or by uniformly reducing the number of temporal frames in the dynamic CT sequence. These dose reduction techniques result in noisy time-attenuation curves (TACs), which can give rise to significant errors in MBF estimation. We seek to investigate whether nonuniformly varying the tube current and/or sampling intervals can yield more accurate MBF estimates for a given dose. Specifically, we try to minimize the dose and obtain the most accurate MBF estimate by addressing the following questions: when in the TAC should the CT data be collected and at what tube current(s)? We hypothesize that increasing the sampling rate and/or tube current during the time frames when the myocardial CT number is most sensitive to the flow rate, while reducing them elsewhere, can achieve better estimation accuracy for the same dose. We perform simulations of contrast agent kinetics and CT acquisitions to evaluate the relative MBF estimation performance of several clinically viable variable acquisition methods. We find that variable temporal and tube current sequences can be performed that impart an effective dose of 5.5 mSv and allow for reductions in MBF estimation root-mean-square error on the order of 20% compared to uniform acquisition sequences with comparable or higher radiation doses.

Fractional flow reserve in 2017: current data and everyday practice

INTRODUCTION

Fractional flow reserve (FFR) is an objective physiological index utilized in coronary angiography. It expresses the blood flow in the presence of a coronary artery stenosis as a fraction of the normal blood flow and gives information regarding the functional significance of the lesion. FFR guided percutaneous coronary intervention (PCI) has been shown to be superior to angiography guided PCI in several trials and registries. In addition, it appears that the use of FFR may also be preferable from an economic perspective. Areas covered: This article will cover the physiological principles underpinning FFR, the landmark clinical trials that have established its diagnostic utility and the current recommendations for the use of the procedure in daily practice. We will also examine potential future directions for the technology and try to predict how its use will evolve in the next five years. Expert commentary: We see FFR as an essential diagnostic tool in the modern catheterization laboratory, enabling physicians to make optimal decisions regarding percutaneous coronary intervention for an individual patient. It must be stated however that FFR is an adjunctive invasive functional tool that must be used in conjunction with sensible clinical history and exam findings pertaining to the individual patient. We expect that the results of FAME3 will further establish the role of FFR in risk stratifying patients with 3 vessel disease by utilizing a functional SYNTAX score.

Prognostic value of normal positron emission tomography myocardial perfusion imaging in patients with known or suspected coronary artery disease: a meta-analysis

OBJECTIVE

Several studies have confirmed high diagnostic performance of positron emission tomography (PET) myocardial perfusion imaging (MPI) in patients with known or suspected coronary artery disease. However, whether the superior diagnostic accuracy could translate into improved mortality outcomes remains unknown. The aim of this study was to define the prognostic value of normal PET MPI.

METHODS

PubMed and EMBASE were searched to identify related studies up to June 2016. All studies using PET MPI to evaluate subjects with known or suspected coronary artery disease and providing absolute number of patients with a negative test and primary data on clinical outcomes with a follow-up time ≥3 months were included for analysis.

RESULTS

The search yielded 11 studies comprising 20,471 patients for final analysis. The negative-predictive value (NPV) for cardiac death, all-cause death and major adverse cardiovascular events (MACE) were 98.80% [95% confidence interval (CI), 97.64%-99.39%], 94.89% (95% CI: 92.99-96.30%) and 90.26% (95% CI: 78.01-96.03%), over 36.9 months of follow-up for cardiac death, over 26.8 months for all-cause death and 35.7 months for MACE. The corresponding annualized event rates were 0.39%, 2.29% and 3.27%, respectively. In subgroup analyses of different imaging analysis methods for PET MPI, studies using perfusion abnormity had a similar NPV as compared with those using coronary flow reserve (98.46% vs 98.86%, p-value = NS), with a corresponding annualized event rate after negative tests (equal to 1 - NPV) as 0.45% and 0.42%, respectively.

CONCLUSION

Normal PET has a high NPV for cardiac death, MACE and all-cause mortality. Different indexes used for PET imaging analysis have a comparable prognostic value. Advances in knowledge: A normal PET MPI conferred a very low risk of cardiac death of 0.39% per year, which is close to that of a normal aged-matched population.

New solid state cadmium-zinc-telluride technology for cardiac single photon emission computed tomographic myocardial perfusion imaging

INTRODUCTION

Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is well established as diagnostic test for patients with suspected or known coronary artery disease. New camera systems have been developed with cadmium-zinc-telluride (CZT) detectors, novel collimator designs and reconstruction software. Areas covered: We review the current state of cardiac SPECT, advances in conventional camera technology and the development and clinical validation of solid-state CZT cameras. Expert commentary: The development of CZT systems is timely and addresses current issues for clinical SPECT imaging. These systems have a significant increase in photon sensitivity, permitting much lower radiation patient doses at a time when the lay and medical communities are very concerned about the radiation doses resulting from medical imaging. The increased count sensitivity permits shorter acquisition times and greater patient throughput which may address the ongoing and increasing issue of decreased funding for healthcare and, particularly, diagnostic imaging. The improved image resolution should improve diagnostic accuracy and increase the value of SPECT imaging for management of patients with CAD at a time of significant competition from other imaging modalities.

Sequential SPECT/CT imaging for detection of coronary artery disease in a large cohort: evaluation of the need for additional imaging and radiation exposure

BACKGROUND

Performing both single photon emission computerized tomography (SPECT) and coronary computed tomography angiography (CCTA) in patients suspected for coronary artery disease (CAD) leads to increased radiation exposure. We evaluated the need for additional imaging and following implications for radiation exposure of a sequential SPECT/computed tomography (CT) algorithm.

METHODS AND RESULTS

5018 consecutive patients without history of CAD were referred for stress-first SPECT and coronary artery calcium (CAC) scoring. If stress SPECT was abnormal, additional rest SPECT and, if feasible, CCTA were acquired. Stress SPECT was normal in 2617 patients (52%). CCTA was not performed in 1289 of the 2401 patients referred for additional imaging (54%), mainly because of severe CAC (47%) or fast/irregular heart rate (22%). 642 patients with abnormal SPECT underwent CCTA, which excluded significant CAD in 378 patients (59%). Mean radiation dose was 4.5 ± 0.3 mSv for stress-only imaging and 13.2 ± 3.3 mSv for additional imaging (P < 0.001).

CONCLUSIONS

Half of the patients do not require additional imaging in our sequential SPECT/CT algorithm, which is accompanied with low radiation exposure. CCTA cannot be performed in half of the patients who undergo additional imaging because of (relative) contra-indications. CCTA is able to correct for false-positive SPECT findings in our algorithm.

The FAME Trials: Impact on Clinical Decision Making

Careful and stepwise evaluation of the fractional flow reserve (FFR) index has been performed over the years, culminating in the landmark Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) and Fractional Flow Reserve-Guided Percutaneous Coronary Intervention Plus Optimal Medical Treatment Versus Optimal Medical Treatment Alone in Patients with Stable Coronary Artery Disease (FAME II) trials. Findings from these studies demonstrated unequivocally the overall inadequacy of angiography versus FFR to correctly assess stenosis severity. Thus, proof of concept and clinical applicability was established beyond debate and will be discussed here.

Impact of Early Coronary Revascularization on Long-Term Outcomes in Patients With Myocardial Ischemia on Dobutamine Stress Echocardiography

The role of early coronary revascularization in the management of stable coronary artery disease remains controversial. The aim of this study was to evaluate the impact of early coronary revascularization on long-term outcomes (>10 years) after an ischemic dobutamine stress echocardiography (DSE) in patients with known or suspected coronary artery disease. Patients without stress-induced ischemia on DSE and those who underwent late coronary revascularization (>90 days after DSE) were excluded. The final study cohort consisted of 905 patients. A DSE with a peak wall motion score index of 1.1 to 1.7 was considered mild to moderately abnormal (n = 460), and >1.7 was markedly abnormal (n = 445). End points were all-cause and cardiac mortality. The impact of early coronary revascularization on outcomes was assessed using Kaplan-Meier survival analysis and Cox's proportional hazard regression models. Early coronary revascularization was performed in 222 patients (percutaneous coronary intervention in 113 [51%] and coronary artery bypass grafting in 109 patients [49%]). During a median follow-up time of 10 years (range 8 to 15), 474 deaths (52%) occurred, of which were 241 (51%) due to cardiac causes. Kaplan-Meier survival curves showed that both in patients with a markedly abnormal DSE and a mild-to-moderately abnormal DSE, early revascularization was associated with better long-term outcomes. Multivariable analyses revealed that early revascularization had a beneficial effect on all-cause mortality (hazard ratio 0.60, 95% confidence interval 0.46 to 0.79) and cardiac mortality (hazard ratio 0.49, 95% confidence interval 0.34 to 0.72). In conclusion, early coronary revascularization has a beneficial impact on long-term outcomes in patients with myocardial ischemia on DSE. Early coronary revascularization was associated with better outcomes not only in patients with a markedly abnormal DSE but also in those with a mild to moderately abnormal DSE.

Usefulness of the novel risk estimation software, Heart Risk View, for the prediction of cardiac events in patients with normal myocardial perfusion SPECT

BACKGROUND

Myocardial perfusion single-photon emission-computed tomography (SPECT) can predict cardiac events in patients with coronary artery disease with high accuracy; however, pseudo-negative cases sometimes occur. Heart Risk View, which is based on the prospective cohort study (J-ACCESS), is a software for evaluating cardiac event probability.

OBJECTIVES

We examined whether Heart Risk View was useful to evaluate the cardiac risk in patients with normal myocardial perfusion SPECT (MPS).

METHODS AND RESULTS

We studied 3461 consecutive patients who underwent MPS to detect myocardial ischemia and those who had normal MPS were enrolled in this study (n = 698). We calculated cardiac event probability by Heart Risk View and followed-up for 3.8 ± 2.4 years. The cardiac events were defined as cardiac death, non-fatal myocardial infarction, and heart failure requiring hospitalization. During the follow-up period, 21 patients (3.0 %) had cardiac events. The event probability calculated by Heart Risk View was higher in the event group (5.5 ± 2.6 vs. 2.9 ± 2.6 %, p < 0.001). According to the receiver-operating characteristics curve, the cut-off point of the event probability for predicting cardiac events was 3.4 % (sensitivity 0.76, specificity 0.72, and AUC 0.85). Kaplan-Meier curves revealed that a higher event rate was observed in the high-event probability group by the log-rank test (p < 0.001).

CONCLUSION

Although myocardial perfusion SPECT is useful for the prediction of cardiac events, risk estimation by Heart Risk View adds more prognostic information, especially in patients with normal MPS.

How should CT coronary angiography be integrated into the management of patients with chest pain and how does this affect outcomes?

When examining the role of a diagnostic test in clinical practice, consideration must be placed not only on the accuracy of the result, but also its impact on patient care and outcomes. Proving a direct effect on outcomes may be difficult because the impact of the diagnostic test largely depends on the clinician's interpretation and consequent actions as well as the patient's response to changes in their diagnosis, investigations, and treatment. Recent major clinical trials of symptomatic patients with suspected coronary heart disease (CHD) have shown that computed tomography coronary angiography (CTCA) can markedly clarify the diagnosis and lead to major changes in patient investigation and management including the use of invasive angiography, preventative therapies, and coronary revascularization. Thus, when added to our existing clinical tools, such as exercise electrocardiography, CTCA represents a powerful method of identifying and excluding CHD. Furthermore, it can identify patients with prognostically relevant non-obstructive CHD and, with recent technological advances, will be able to assess the functional impact of anatomically detected coronary artery stenoses. Overall, the routine integration of CTCA into the investigation of patients with chest pain improves clinical diagnostic certainty that has led to better targeting of investigations and evidence-based treatments that have ultimately translated into improved clinical outcomes.

Refractory Hypotension after Liver Allograft Reperfusion: A Case of Dynamic Left Ventricular Outflow Tract Obstruction

Hypotension after reperfusion is a common occurrence during liver transplantation following the systemic release of cold, hyperkalemic, and acidic contents of the liver allograft. Moreover, the release of vasoactive metabolites such as inflammatory cytokines and free radicals from the liver and mesentery, compounded by the hepatic uptake of blood, may also cause a decrement in systemic perfusion pressures. Thus, the postreperfusion syndrome (PRS) can materialize if hypotension and fibrinolysis occur concomitantly within 5 min of reperfusion. Treatment of the PRS may require the administration of inotropes, vasopressors, and intravenous fluids to maintain hemodynamic stability. However, the occurrence of the PRS and its treatment with inotropes and calcium chloride may lead to dynamic left ventricular outflow tract obstruction (DLVOTO) precipitating refractory hypotension. Expedient diagnosis of DLVOTO with transesophageal echocardiography is extremely vital in order to avoid potential cardiovascular collapse during this critical period.

Accuracy and usefulness of noninvasive fractional flow reserve from computed tomographic coronary angiography: comparison with myocardial perfusion imaging, echocardiographic coronary flow reserve, and invasive fractional flow reserve

We present a case of coronary artery disease with intermediate stenosis in the proximal left anterior descending artery, which was evaluated using multiple functional modalities. FFR_CT demonstrated a significant perfusion abnormality in the LAD, and the value of FFR_CT (0.68) was similar to the value measured by invasive FFR (0.67). However, the other modalities gave discrepant results. In particular, perfusion scintigraphy with thallium showed no evidence of an inducible perfusion abnormality in the LAD territory. The patient was treated by PCI for two tandem lesions in the LAD. FFR_CT may have potential as a default noninvasive method for assessment of coronary anatomy and physiology.

Dipyridamole stress myocardial perfusion by computed tomography in patients with left bundle branch block

Background

Functional tests have limited accuracy for identifying myocardial ischemia in patients with left bundle branch block (LBBB).

Objective

To assess the diagnostic accuracy of dipyridamole-stress myocardial computed tomography perfusion (CTP) by 320-detector CT in patients with LBBB using invasive quantitative coronary angiography (QCA) (stenosis ≥ 70%) as reference; to investigate the advantage of adding CTP to coronary computed tomography angiography (CTA) and compare the results with those of single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy.

Methods

Thirty patients with LBBB who had undergone SPECT for the investigation of coronary artery disease were referred for stress tomography. Independent examiners performed per-patient and per-coronary territory assessments. All patients gave written informed consent to participate in the study that was approved by the institution’s ethics committee.

Results

The patients’ mean age was 62 ± 10 years. The mean dose of radiation for the tomography protocol was 9.3 ± 4.6 mSv. With regard to CTP, the per-patient values for sensitivity, specificity, positive and negative predictive values, and accuracy were 86%, 81%, 80%, 87%, and 83%, respectively (p = 0.001). The per-territory values were 63%, 86%, 65%, 84%, and 79%, respectively (p < 0.001). In both analyses, the addition of CTP to CTA achieved higher diagnostic accuracy for detecting myocardial ischemia than SPECT (p < 0.001).

Conclusion

The use of the stress tomography protocol is feasible and has good diagnostic accuracy for assessing myocardial ischemia in patients with LBBB.

Prediction of 14-year outcomes in patients with a limited exercise capacity: Utility of dobutamine myocardial perfusion imaging in a high-risk population

OBJECTIVE

Despite multiple studies on the diagnostic and prognostic use of dobutamine myocardial perfusion imaging (MPI), information on its long-term prognostic value is scarce. The aim of this study was to assess the value of this technique for the prediction of very long-term outcome.

METHODS

A total of 721 patients with limited exercise capacity underwent dobutamine MPI for the evaluation of suspected or known coronary artery disease. 719 of 721 patients attended follow-up (99.7%). Twenty-eight patients who underwent early coronary revascularization were excluded from analysis. Endpoints were all-cause mortality, cardiac death, nonfatal infarction, and coronary revascularization. Kaplan-Meier survival curves were constructed, and univariate and multivariate analyses were performed to identify predictors of long-term outcome.

RESULTS

The mean age of patients was 60 ± 11 years, and 61% were male. Myocardial perfusion abnormalities were present in 381 patients (55%) and included fixed defects in 190 patients (27%) and reversible defects in 191 patients (28%). During a median follow-up time of 14 years (range 0-16), 295 deaths occurred (43%), of which 158 were cardiac deaths (23%). Nonfatal myocardial infarction occurred in 35 (5%), and late coronary revascularization was performed on 133 patients (19%). An abnormal dobutamine MPI provided significant prognostic information for prediction of cardiac death, hard cardiac events, and MACE, after adjustment for significant clinical variables and stress test variables.

CONCLUSIONS

Dobutamine MPI provides incremental prognostic information for the prediction of cardiovascular outcomes in patients with limited exercise capacity. The long-term prognosis of patients with limited exercise capacity who have an abnormal dobutamine MPI is significantly worse than those with a normal MPI.

Fractional Flow Reserve Guided Percutaneous Coronary Intervention Improves Clinical Outcome with Reduced Cost in Contemporary Clinical Practice

BACKGROUND

Fractional flow reserve (FFR) is currently considered as the gold standard for evaluating the functional significance of coronary stenosis. However, its potential benefits in real-world practice remain unknown in China. This study aimed to test the hypothesis that the use of FFR is associated with improved outcome and reduced cost in Chinese real-world clinical practice.

METHODS

A retrospective cohort study was carried out using the database of Second Affiliated Hospital of Zhejiang University, a tertiary and high-volume center in China. Clinical events were compared using the Cox proportional hazards model during a median follow-up of 13 months.

RESULTS

The study cohort consisted of 366 consecutive patients referred for coronary revascularization with adjunct FFR and 366 matched controls, from 2010 to 2014. Major adverse cardiac events (MACEs) (death, myocardial infarction, repeated revascularization, or hospitalization for angina) at 4 years were found in 12.0% of angiography-guided patients and 4.9% in the FFR-guided group (P < 0.001). The mean number of implanted stents was significantly lower in FFR treated subjects (0.52 ± 0.82 stents) compared with the angiography-guided group (0.93 ± 0.96 stents) (P < 0.001). No difference in overall costs at initial hospitalization was observed between angiography-guided percutaneous coronary intervention (PCI) compared with FFR-guided PCI (RMB 33,000 Yuan, range: RMB 7393-44,700 Yuan) versus RMB 21,200 Yuan (RMB 19,100-47,100 Yuan) (P = 0.54). However, costs for MACEs during follow-up were significantly reduced in the FFR-guided arm (P < 0.001).

CONCLUSIONS

In the contemporary clinical practice, FFR-guided PCI is associated with decreased use of stents, improved clinical outcome, and reduced costs, compared with angiography-guided PCI.

Incremental Prognostic Value of Brachial-Ankle Pulse Wave Velocity to Single-Photon Emission Computed Tomography in Patients with Suspected Coronary Artery Disease

AIM

Arterial stiffness assessed by brachial-ankle pulse wave velocity (baPWV) is predictive of cardiovascular events. This study was designed to investigate whether baPWV has an additional prognostic value to single-photon emission computed tomography (SPECT) in patients with suspected coronary artery disease (CAD).

METHODS

A total of 350 subjects (age, 66.2 ± 10.5 years, 53.4% male) with suspected CAD undergoing myocardial SPECT and baPWV within 30 days were retrospectively analyzed. Cardiovascular events, including cardiovascular death, acute coronary syndrome and ischemic stroke, were assessed. Both fixed and reversible perfusion defects on SPECT were considered abnormal myocardial perfusion imaging (MPI) findings.

RESULTS

During the median follow-up period of 441 days (interquartile range 169-719 days), cardiovascular events occurred in 21 patients (6.0%). In multivariable Cox regression analysis, abnormal MPI [hazard ratio (HR), 2.67; 95% confidence interval (CI), 1.21-10.37; p=0.024] and high baPWV (≥ 1,790 cm/s) (HR, 2.03; 95% CI, 1.08-6.38; p=0.007) were independent predictors of clinical events even after adjusting for possible confounders. Also, high baPWV had an incremental prognostic value to traditional risk factors and abnormal MPI in predicting cardiovascular events (overall Chi-square, from 24.08 to 27.42; p ＜ 0.001). Kaplan-Meier survival curves stratified by baPWV and MPI proved significantly improved prediction of cardiovascular events (log-rank p=0.001).

CONCLUSIONS

baPWV has an incremental prognostic value to traditional risk factors and MPI. Therefore, baPWV can be used to identify subjects at higher risk of cardiovascular events in patients undergoing SPECT.