Predictors of high-risk coronary artery disease in subjects with normal SPECT myocardial perfusion imaging

Multivessel Coronary Artery Disease Presenting as a False-Negative Nuclear Stress Test: A Case of Balanced Ischemia

Myocardial perfusion imaging (MPI) is fundamental to comparing coronary vessel perfusion levels and guides in identifying ischemic areas. However, false negatives, such as balanced ischemia, are important considerations in interpreting these results. In this case report, we describe a 77-year-old female who presented with cardiac chest pain with normal laboratory results, electrocardiogram, and imaging. However, given her history and risk factors, left heart catheterization was performed, which showed triple vessel coronary artery disease.

Improved Performance of PET Myocardial Perfusion Imaging Compared to SPECT in the Evaluation of Suspected CAD

PURPOSE OF REVIEW

Myocardial perfusion imaging (MPI) with single photon emission computed tomography (SPECT) has played a central role in the non-invasive evaluation of patients with obstructive coronary artery disease (CAD) for decades. In this review, we discuss the key differences and advantages of positron emission tomography (PET) MPI over SPECT MPI as it relates to the diagnosis, prognosis, as well as clinical decision-making in patients with suspected CAD.

RECENT FINDINGS

Stress-induced perfusion abnormalities on SPECT help estimate presence, extent, and location of ischemia and flow-limiting obstructive CAD, help with risk stratification, and serve as a gatekeeper to identify patients who will benefit from downstream revascularization versus medical management. Some of the major limitations of SPECT include soft-tissue attenuation artifacts, underestimation of ischemia due to reliance on relative perfusion assessment, and longer protocols with higher radiation dose when performed with traditional equipment. PET MPI addresses most of these limitations and offers better quality images, higher diagnostic accuracy along with shorter protocols and lower radiation dose to the patient. A special advantage of PET scanning lies in the ability to quantify absolute myocardial blood flow and assess true extent of epicardial involvement along with identifying non-obstructive phenotypes of CAD such as diffuse atherosclerosis and microvascular dysfunction. In addition, stress acquisition at/near peak stress with PET allows us to measure left ventricular ejection fraction reserve and myocardial blood flow reserve, which help with identifying patients at a higher risk of future cardiac events and optimally select candidates for revascularization. The several technical advantages of PET MPI position as a superior method to diagnose obstructive and non-obstructive phenotypes of ischemic heart disease affecting the entirety of the coronary circulation offer incremental value for risk stratification and guide post-test management strategy for patients with suspected CAD.

Diagnostic safety of a machine learning-based automatic patient selection algorithm for stress-only myocardial perfusion SPECT

BACKGROUND

Stress-only myocardial perfusion imaging (MPI) markedly reduces radiation dose, scanning time, and cost. We developed an automated clinical algorithm to safely cancel unnecessary rest imaging with high sensitivity for obstructive coronary artery disease (CAD).

METHODS AND RESULTS

Patients without known CAD undergoing both MPI and invasive coronary angiography from REFINE SPECT were studied. A machine learning score (MLS) for prediction of obstructive CAD was generated using stress-only MPI and pre-test clinical variables. An MLS threshold with a pre-defined sensitivity of 95% was applied to the automated patient selection algorithm. Obstructive CAD was present in 1309/2079 (63%) patients. MLS had higher area under the receiver operator characteristic curve (AUC) for prediction of CAD than reader diagnosis and TPD (0.84 vs 0.70 vs 0.78, P < .01). An MLS threshold of 0.29 had superior sensitivity than reader diagnosis and TPD for obstructive CAD (95% vs 87% vs 87%, P < .01) and high-risk CAD, defined as stenosis of the left main, proximal left anterior descending, or triple-vessel CAD (sensitivity 96% vs 89% vs 90%, P < .01).

CONCLUSIONS

The MLS is highly sensitive for prediction of both obstructive and high-risk CAD from stress-only MPI and can be applied to a stress-first protocol for automatic cancellation of unnecessary rest imaging.

Artificial intelligence for disease diagnosis and risk prediction in nuclear cardiology

Artificial intelligence (AI) techniques have emerged as a highly efficient approach to accurately and rapidly interpret diagnostic imaging and may play a vital role in nuclear cardiology. In nuclear cardiology, there are many clinical, stress, and imaging variables potentially available, which need to be optimally integrated to predict the presence of obstructive coronary artery disease (CAD) or predict the risk of cardiovascular events. In spite of clinical awareness of a large number of potential variables, it is difficult for physicians to integrate multiple features consistently and objectively. Machine learning (ML) is particularly well suited to integrating this vast array of information to provide patient-specific predictions. Deep learning (DL), a branch of ML characterized by a multi-layered convolutional model architecture, can extract information directly from images and identify latent image features associated with a specific prediction. This review will discuss the latest AI applications to disease diagnosis and risk prediction in nuclear cardiology with a focus on potential clinical applications.

Cardiac computed tomography-derived coronary artery volume to myocardial mass

In the absence of disease impacting the coronary arteries or myocardium, there exists a linear relationship between vessel volume and myocardial mass to ensure balanced distribution of blood supply. This balance may be disturbed in diseases of either the coronary artery tree, the myocardium, or both. However, in contemporary evaluation the coronary artery anatomy and myocardium are assessed separately. Recently the coronary lumen volume to myocardial mass ratio (V/M), measured noninvasively using coronary computed tomography angiography (CTCA), has emerged as an integrated measure of myocardial blood supply and demand in vivo. This has the potential to yield new insights into diseases where this balance is altered, thus impacting clinical diagnoses and management. In this review, we outline the scientific methodology underpinning CTCA-derived measurement of V/M. We describe recent studies describing alterations in V/M across a range of cardiovascular conditions, including coronary artery disease, cardiomyopathies and coronary microvascular dysfunction. Lastly, we highlight areas of unmet research need and future directions, where V/M may further enhance our understanding of the pathophysiology of cardiovascular disease.

Nuclear Cardiology in Women and Underrepresented Minority Populations

PURPOSE OF REVIEW

To outline sex-specific features of coronary artery disease (CAD) that should be considered in the assessment of women, including those from ethnic minority populations with suspected stable ischemic heart disease (IHD). Second, to determine the latest nuclear imaging tools available to assess microvascular CAD.

RECENT FINDINGS

Latest studies indicate that women are more likely to have ischemia with no obstructive coronary arteries (INOCA) and paradoxically have worse outcomes. Therefore, the evaluation of women with suspected IHD should include assessing microvascular and epicardial coronary circulation. The prevalence of CAD is increasing in younger women due to the increased cardiovascular disease (CVD) risk burden. CAD is often underrecognized in these patients. There is increasing recognition that INOCA is not benign and should be accurately diagnosed and managed. Nuclear imaging assesses the full spectrum of CAD from microvascular CAD to multivessel obstructive epicardial CAD. Further research on myocardial blood flow (MBF) assessment with PET MPI is needed.

Role of coronary computed tomography angiography (CTA) post the ISCHEMIA trial: Precision prevention based on coronary CTA-derived coronary atherosclerosis

The International Study of Comparative Health Effectiveness With Medical and Invasive Approaches (ISCHEMIA) trial has been recently published and suggested the importance of the selection of patients at high risk for future cardiovascular disease events and the enhancing optimal medical therapy. In the ISCHEMIA trial, coronary computed tomography angiography (CTA) was performed in most of the patients to exclude high-risk patients and those without obstructive coronary artery disease (CAD) who should not be randomized. Coronary CTA has been widely used as a non-invasive diagnostic modality to assess patients with suspected CAD. Currently, the international guidelines allow use of coronary CTA as a class I recommendation for patients with chest pain. Besides, in the numerous multicenter trials, the emerging role of coronary CTA has proven that it could soon become the standard for monitoring CAD and identifying patients at high risk of future cardiovascular events. In this review article, we summarize the current evidence on coronary CTA and the potential role of coronary CTA after the ISCHEMIA trial for patients with CAD. Risk assessment using detailed CAD data obtained non-invasively and prevention of future cardiovascular events through improved medical care will become increasingly essential for the precision treatment and prevention of CAD in patients.

Extensive and balanced reduction of myocardial blood flow in patients with suspected obstructive coronary artery disease: 15O-water PET study

BACKGROUND

Detection of obstructive coronary artery disease (CAD) by stress myocardial perfusion imaging (MPI) is conventionally based on relative differences in perfusion. This may lead to either underestimation of the extent of myocardial ischemia, or the ischemia might be completely missed in case of balanced perfusion reduction. Using absolute quantification of myocardial blood flow (MBF) by positron emission tomography (PET), we evaluated how common are extensive and balanced myocardial perfusion abnormalities in symptomatic patients with suspected obstructive CAD.

METHODS AND RESULTS

Among 758 consecutive symptomatic patients undergone coronary computed tomography angiography (CTA), 286 patients subsequently underwent quantitative 15O-water adenosine-stress PET MPI to assess the hemodynamic significance of suspected obstructive stenosis. Out of these, 46 (16%) patients had reduced (≤2.3 ml/g/min) absolute stress MBF in all three standard coronary territories (LAD, LCX, RCA). Subsequently, relative stress MBF in each coronary territory was calculated, considering a territory with the highest absolute stress MBF as a reference region. Among the 46 patients, 72% had significant regional heterogeneity in myocardial perfusion (defined as having ≥1 territory with relative stress MBF <80%) while the remaining 28% (4.5% of the whole MPI cohort) showed balanced perfusion reduction (all relative MBF values ≥80%).

CONCLUSIONS

Among symptomatic patients with suspected obstructive stenosis on coronary CTA, quantitative PET revealed that 16% of patients had reduced stress MBF involving all three coronary artery territories, of whom approximately one third showed balanced reduction. Thus, in 4.5% of the patients the perfusion abnormalities could have been missed by conventional relative MPI analysis.

Early onset of left ventricular regional asynchrony in arteries with sub-clinical stenosis

BACKGROUND

Asynchrony has been reported to be a marker of ischemic-induced left ventricular dysfunction, the magnitude of which correlates with extent of epicardial coronary disease. We wished to determine whether normal-appearing arterial territories with mild degrees of asynchrony have lower 82Rb PET absolute myocardial blood flow (MBF) and/or lower myocardial flow reserve (MFR).

METHODS AND RESULTS

Data were examined retrospectively for 105 patients evaluated for known/suspected CAD who underwent rest/regadenoson-stress 82Rb PET/CT and quantitative coronary angiography. Rest and stress absolute MBF and MFR were quantified from first-pass 82Rb PET curves. Regional relative myocardial perfusion summed stress score (SSS), summed rest score (SRS), regional phase bandwidth (BW), and regional semi-quantitative asynchrony visual scores of (Asynch) were assessed. We found that in apparently normal arteries (SSS < 4, SRS < 4 and stenosis < 70%), those with abnormally low MFR < 2.0 compared to those with MFR ≥ 2.0 had larger phase BW (186 ± 79° vs 158 ± 67°, P = .02), and more visually apparent Asynch (5.7 ± 4.2 vs 3.9 ± 3.6, P = .02), which was associated with increasing stenosis values (ρ = 0.44, P < .0001).

CONCLUSION

A subgroup of coronary territories with normal relative perfusion and normal or non-obstructive coronary disease may have reduced MFR, which is signaled physiologically by a mild degree of left ventricular asynchrony.

Diagnostic accuracy of stress-only myocardial perfusion SPECT improved by deep learning

PURPOSE

Deep convolutional neural networks (CNN) for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has been used to improve the diagnostic accuracy of coronary artery disease (CAD). This study was to design and evaluate a deep learning (DL) approach to automatic diagnosis of myocardial perfusion abnormalities from stress-only MPI.

METHODS

The new DL approach developed for this study was compared to a conventional quantitative perfusion defect size (DS) method. A total of 37,243 patients (51.5% males) undergone stress ^99mTc-Tetrofosmin or ^99mTc-Sestamibi MPI were selected retrospectively from Yale New Haven Hospital. Patients were dichotomized as studies with normal (75.4%) or abnormal (24.6%) myocardial perfusion based on final diagnoses of clinical nuclear cardiologists. Stress myocardial perfusion defect size was calculated using Yale quantitative analytic software. A deep CNN was trained using the circumferential count profile maps derived from SPECT MPI and was evaluated for the diagnosis of perfusion abnormality with a 5-fold cross-validation approach. In each fold, 27,933, 1862 and 7448 patients were used as training, validation and testing datasets, respectively. The area under the receiver-operating characteristic curve (AUC) was calculated and analyzed for all patients as well as for the eight sub-groups classified based on patient genders, quantitative algorithms, radioactive tracers and SPECT cameras.

RESULTS

The AUC value resulted from the DL method was significantly higher than that from the DS method (0.872 ± 0.002 vs. 0.838 ± 0.003, p < 0.01). Across the eight sub-groups, the DL method provided more consistent AUC values in terms of smaller standard deviation and higher diagnostic accuracy and specificity, but slightly lower sensitivity than the DS method (AUC: 0.865 ± 0.010 vs. 0.838 ± 0.019, Accuracy: 82.7% ± 2.5% vs. 78.5% ± 3.6%, Specificity: 84.9% ± 3.7% vs. 77.5% ± 6.5%, Sensitivity: 74.4% ± 4.2% vs. 79.8% ± 5.8%).

CONCLUSIONS

The incorporation of deep learning for stress-only MPI has a considerable potential to improve the diagnostic accuracy and consistency in the detection of myocardial perfusion abnormalities.

Left ventricular dyssynchrony and abnormalities in wall motion, assessed by gated-SPECT as ischemic auxiliary markers

INTRODUCTION

Left ventricular dyssynchrony (LVD) quantified by gated myocardial perfusion studies (MPS), through phase analysis (PA), has shown controversial results in myocardial stunning.

OBJECTIVES

Assessment of LVD and regional wall motion abnormalities (RWMA) in normal and ischemic patients.

METHODS

A cohort of 172 patients were studied. Summed Stress Score (SSS), Summed Resting Score (SRS), and Summed Difference Score (SDS) were evaluated. Group 1-patients with normal MPS (N = 133) and Group 2-patients with myocardial ischemia in the MPS (N = 39). LVD was evaluated through PA and RWM by visual analysis.

RESULTS

SSS 0 vs 9.8 ± 3.9 P = .0001; SDS 0 vs 9.8 ± 3.9 P = .0001; SRS 0 vs 0 P = NS, in G1 and G2. Significant differences were found in LVD between G1 and G2, bandwidth 36 ± 14 vs 63 ± 46 P = .0001; standard deviation 16 ± 10 vs 26 ± 15 P = .0001. In G1, 16% had LVD vs RWMA in 0%, P = .0001 and in G2, 59% with LVD vs 33% with RWMA, P = .03. Sensitivity for LVD 59% and for RWMA 33%, P = .03 and specificity for LVD 83% and for RWMA 100%, P = .0001.

CONCLUSION

Ischemic patients have LVD post-stress due to myocardial stunning. LVD measured by PA could be a useful tool to identify ischemia.

Feasibility and accuracy of SPECT myocardial perfusion imaging in end-stage lung disease

BACKGROUND

Coronary artery disease (CAD) is associated with increased mortality in patients with chronic lung disease. However, non-invasive diagnostic of CAD is difficult, especially in patients with more advanced disease. Therefore, we aimed to assess the feasibility and accuracy of SPECT-myocardial perfusion imaging (MPI) stress testing with regadenoson in patients with end-stage lung disease (ELD) undergoing assessment of stable CAD.

METHODS

Between January 2012 and May 2018, 102 patients with ELD, who were referred to our institution for lung transplant evaluation, were assessed retrospectively. All patients underwent both stress SPECT-MPI as well as coronary angiography.

RESULTS

The mean age in our population was 57±6 years. All patients had severe pulmonary function impairment. During stress SPECT-MPI 14 patients (14%) reported regadenoson-related symptoms, but only 2 patients (2%) required medical treatment. Coronary angiography revealed obstructive CAD in 20 patients (20%). Among those, 5 patients had abnormal SPECT-MPI and PCI was performed in 3 patients accordingly. In 14 patients with obstructive CAD, revascularization was deferred based on normal SPECT-MPI findings.

CONCLUSIONS

SPECT-MPI using regadenoson is well tolerated in patients with ELD and can help to make decisions about coronary revascularization before lung transplant.

Improved diagnostic accuracy for myocardial perfusion imaging using artificial neural networks on different input variables including clinical and quantification data

OBJECTIVE

Diagnostic accuracy of myocardial perfusion imaging (MPI) is not optimal to predict the result of angiography. The current study aimed at investigating the application of artificial neural network (ANN) to integrate the clinical data with the result and quantification of MPI.

METHODS

Out of 923 patients with MPI, 93 who underwent angiography were recruited. The clinical data including the cardiac risk factors were collected and the results of MPI and coronary angiography were recorded. The quantification of MPI polar plots (i.e. the counts of 20 segments of each stress and rest polar plots) and the Gensini score of angiographies were calculated. Feed-forward ANN was designed integrating clinical and quantification data to predict the result of angiography (normal vs. abnormal), non-obstructive or obstructive coronary artery disease (CAD), and Gensini score (≥10 and <10). The ANNs were designed to predict the results of angiography using different combinations of data as follows: reports of MPI, the counts of 40 segments of stress and rest polar plots, and the count of these 40 segments in addition to age, gender, and the number of risk factors. The diagnostic performance of MPI with different ANNs was compared.

RESULTS

The accuracy of MPI to predict the result of angiography, obstructive CAD, and Gensini score increased from 81.7% to 92.9%, 65.0% to 85.7%, and 50.5% to 92.9%, respectively by ANN using counts and clinical risk factors.

CONCLUSION

The diagnostic accuracy of MPI could be improved by ANN, using clinical and quantification data.

Shock-Wave Therapy Improves Myocardial Blood Flow Reserve in Patients with Refractory Angina: Evaluation by Real-Time Myocardial Perfusion Echocardiography

BACKGROUND

Cardiac shock-wave therapy (CSWT) has been demonstrated as an option for the treatment of patients with refractory angina (RA), promoting immediate vasodilatory effects and, in the long-term, neoangiogenic effects that would be responsible for reducing the myocardial ischemic load. The aim of this study was to determine the effects of CSWT on myocardial blood flow reserve (MBFR) assessed by quantitative real-time myocardial perfusion echocardiography in patients with RA.

METHODS

Fifteen patients (mean age 61.5 ± 12.8 years) with RA who underwent CSWT during nine sessions, over 3 months of treatment, were prospectively studied. A total of 32 myocardial segments with ischemia were treated, while another 31 did not receive therapy because of technical limitations. Myocardial perfusion was evaluated at rest and after dipyridamole stress (0.84 mg/kg) before and 6 months after CSWT, using quantitative real-time myocardial perfusion echocardiography. Clinical effects were evaluated using Canadian Cardiovascular Society grading of angina and the Seattle Angina Questionnaire.

RESULTS

The ischemic segments treated with CSWT had increased MBFR (from 1.33 ± 0.22 to 1.74 ± 0.29, P < .001), a benefit that was not observed in untreated ischemic segments (1.51 ± 0.29 vs 1.54 ± 0.28, P = .47). Patients demonstrated increased global MBFR (from 1.78 ± 0.54 to 1.89 ± 0.49, P = .017). Semiquantitative single-photon emission computed tomographic analysis of the treated ischemic segments revealed a score reduction from 2.10 ± 0.87 to 1.68 ± 1.19 (P = .024). There was improvement in Canadian Cardiovascular Society score (from 3.20 ± 0.56 to 1.93 ± 0.70, P < .05) and in Seattle Angina Questionnaire score (from 42.3 ± 12.99 to 71.2 ± 14.29, P < .05). No major cardiovascular events were recorded during follow-up.

CONCLUSIONS

CSWT improved MBFR in ischemic segments, as demonstrated by quantitative real-time myocardial perfusion echocardiography. These results suggest that CSWT has the potential to increase myocardial blood flow, with an impact on symptoms and quality of life in patients with RA.

My warranty has expired: I need to be retested

The concept of warranty period, the duration of time during which the patient's risk remains low, is appealing. However, some points remain to be resolved before its translation in the clinical arena. Methodological issues should be standardized in order to compare the results of studies in different patient populations. Also, the definition of a "normal" study should always take into consideration the history of prior revascularization, the achieved level of exercise, and the stressor used. The promise of warranty can be questioned by the patient's baseline demographic and clinical characteristics and may also be influenced by life-style modification in the course of the follow-up. The "warranty period" concept should shift from data reflecting the time to a cardiac event to the development of ischemia, given an opportunity for intervention before a cardiac event occurs. In this context, clarify the role of serial imaging can be extremely useful, in particular to evaluate if and when retesting a patient after a normal scan.

Diagnosis and Prognosis of Coronary Artery Disease with SPECT and PET

PURPOSE OF REVIEW

Radionuclide myocardial perfusion imaging (MPI) continues to be the most reliable modality for diagnosis of hemodynamically significant coronary artery disease (CAD). The application of radionuclide MPI using single photon emission computed tomography (SEPCT) and positron emission tomography (PET) for CAD is reviewed, with emphasis on diagnosis and risk stratification.

RECENT FINDINGS

Contemporary studies have reported the diagnostic and prognostic value of novel imaging protocols, employing stress-first or stress-only approach. In addition, the superior diagnostic value of PET has been established with a role of assessment of myocardial blood flow to improve risk stratification. The utility of MPI in special populations, such as the elderly, women, and diabetic patients has also been recently evaluated. Furthermore, multicenter studies have reported a similar diagnostic and prognostic value of radionuclide MPI compared with other functional and anatomical techniques for CAD. Radionuclide MPI with SPECT and PET are efficacious for diagnosis and prognosis of CAD. Its universal application in varied patient populations highlights its excellent clinical effectiveness.

Prognostic value of left ventricular dyssynchrony evaluated by gated myocardial perfusion imaging in patients with chronic kidney disease and normal perfusion defect scores

BACKGROUND

This study aimed to investigate whether indices of left ventricular (LV) dyssynchrony by gated myocardial perfusion SPECT (GMPS) could be useful to predict prognosis in chronic kidney disease (CKD) patients with normal perfusion defect scores.

METHODS

One hundred and sixty-seven CKD patients with normal perfusion defect scores on adenosine-stress 201Tl GMPS and no previous history of overt heart diseases were enrolled. Phase standard deviation (PSD) and bandwidth (BW) were automatically calculated from GMPS. The major adverse cardiac events (MACEs) for a mean of 560 days were defined as sudden cardiac death, fatal arrhythmias, and acute coronary syndrome requiring urgent coronary revascularization. Patients were divided into two groups according to the presence or absence of MACEs.

RESULTS

The MACEs occurred in 12 patients (7.1%). Patients who experienced MACEs showed significantly higher PSD and wider BW than those who did not. In the Kaplan-Meier event-free survival analysis, cardiac event rate was significantly higher in the high-PSD and wide-BW group (n = 81) than in the low-PSD and narrow-BW group (n = 71) (P = .002). The multivariate regression analysis revealed that the PSD was associated with MACEs (odds ratio 1.33, 95% confidence interval 1.05-1.69, P = .01).

CONCLUSION

The LV dyssynchrony indices from GMPS may be novel prognostic predictors in CKD patients with normal perfusion defect scores.

Difficulties of Diagnostics of Obstructive Coronary Artery Lesions in Patients with Stable Ischemic Heart Disease and Possibilities of Single-Photon Emission Computed Tomography

PURPOSE

to assess diagnostic capabilities of single-photon emission computed tomography (SPECT) in the detection of obstructive coronary artery (CA) lesions, depending on the meeting appropriate use criteria.

MATERIALS AND METHODS

We used in this retrospective analysis data from 107 patients with previously diagnosed ischemic heart disease (IHD) or in need to exclude it, who were hospitalized in inpatient departments of the Research Institute for Complex Issues of Cardiovascular Diseases in the period from 2012 to 2015. All patients underwent coronary angiography (CAG) and SPECT (the time interval between the studies did not exceed 3 months) for detection of hemodynamically significant CA stenoses. Patients were distributed into two groups according SPECT imaging appropriateness score: group 1-88 patients with score 7-9 (in whom SPECT imaging was appropriate), group 2-19 patients with score 1-6 (in whom SPECT imaging was uncertain, possibly appropriate, or inappropriate.

RESULTS

Clinical signs and symptoms of angina pectoris were predominantly found in group 1 patients (p=0.499). Asymptomatic patients were more likely to be found in group 2 (p&lt;0.001). Group 1 patients commonly had high pretest probability (PTP) (over 90 %, p&lt;0.001), whereas group 2 patients commonly had low PTP (5-10 %, p&lt;0.001). Mean PTP was 77 and 58 % in groups 1 and 2, respectively (p=0.003). According to positive SPECT imaging, significant CA lesions were more often found in group 1 compared to group 2 (31.8 and 10.5 %, respectively, p=0.060). Two- and three-vessel disease prevailed in group 1 (25 % and 14.7 %) according the analysis of prevalence and location of hemodynamically significant CA lesions, although the data did not reach statistical significance (p=0.057 and p=0.073). Stenoses &gt;70 % were more commonly detected in group 1, compared to group 2: in anterior descending artery 52.3 vs. 5.3 % (p&lt;0.001), circumflex artery 35.2 vs. 10.5 %; (p=0.034), right coronary artery 34.1 vs. 10.5 % (p=0.041). The sensitivity in both groups was rather low (40 % vs. 25 %), whereas specificity was 83 % in group 1 and 93 % in group 2.

CONCLUSION

According to clinical examination, patients with IHD and indications for SPECT imaging more often had obstructive CA lesions (63.6 %), than patients with questionable or no indications (21.1 %). However, rate of positive findings during stress tests with SPECT imaging was low in both groups and did not differ significantly (p=0.06). Despite high specificity of SPECT imaging, its sensitivity was low in both groups.

Left ventricular functional parameters by gated SPECT myocardial perfusion imaging in a Latin American country

BACKGROUND

There is paucity of data on left ventricular (LV) functional parameters using gated SPECT myocardial perfusion imaging (MPI) from the Latin American region. This study provides detailed information in low-risk patients both at rest and during exercise.

METHODS AND RESULTS

We studied 90 patients (50 men) with a very low likelihood of coronary artery disease. Gated-SPECT MPI was performed with Tc-99m MIBI using a 2-day protocol, with 16 frames/R-R cycle. The LV ejection fraction and volumes were not different between the rest and post-stress images. LVEF was 68 ± 7% post-stress and 70 ± 7% at rest in women, and 62 ± 7% and 63 ± 7%, respectively, in men (P = .19, .26). LV volumes were larger in men than women (P < .01). There were no differences in most variables obtained at rest or post-stress. Transient ischemic dilatation was similar, with upper limits of 1.20 and 1.19 in women and men, respectively (P = NS).

CONCLUSIONS

These data could prove helpful for the interpretation of gated SPECT MPI data in Latin America using identical protocol as used in this study.

Predictors of severe stenosis at invasive coronary angiography in patients with normal myocardial perfusion imaging

Purpose

Normal myocardial perfusion imaging (MPI) is associated with excellent prognosis. However, in patients with persisting symptoms, it may be difficult to determine the patients in whom invasive angiography is justified to rule out false negative MPI. We evaluated predictors for severe stenosis at invasive angiography in patients with persisting symptoms after normal MPI.

Methods

229 consecutive patients with normal MPI, without previous bypass surgery, underwent invasive angiography within 6 months. Older age was defined as >65 years. Multivariable analyses were performed to adjust for differences in baseline variables.

Results

Mean age was 62 ± 11 years, 48% were women. Severe stenosis was observed in 34%, and of these patients 60% had single-vessel disease (not left main coronary artery disease). After adjusting for several variables, including diabetes, smoking status, hypertension and hypercholesterolaemia, predictors of severe stenosis were male gender, odds ratio (OR) 2.7 (95% confidence interval (CI) 1.5–4.9), older age, OR 1.9 (95% CI 1.02–3.54) previous PCI, OR 2.0 (95% CI 1.0–4.3) and typical angina, OR 2.5 (95% CI 1.4–4.6).

Conclusions

Increasing age, male gender, previous PCI and typical symptoms are predictors of severe stenosis at invasive coronary angiography in patients with normal MPI. The majority of these patients have single-vessel disease.

Reconciling discordant myocardial perfusion imaging and coronary angiography

A common clinical conundrum presents itself in the discordance between nuclear stress testing and invasive coronary angiography (ICA) in the patient presenting with angina. A patient with an abnormal perfusion scan and "normal coronary angiography" may result in the patient's symptoms being dismissed as "non-cardiac." Alternatively, a patient with a "normal perfusion study," who nonetheless undergoes ICA and is found to have significant coronary artery disease may confound efforts to risk stratify and potentially treat patients with angina. This paper will review the current evidence to explain these apparent paradoxical scenarios.

Review of cardiovascular imaging in the journal of nuclear cardiology in 2016: Part 2 of 2-myocardial perfusion imaging

In 2016, the Journal of Nuclear Cardiology published many high-quality articles. Similar to previous years, we will summarize here a selection of the articles that were published in the Journal in 2016 to provide a concise review of the main advancements that have recently occurred in the field. In the first article of this two-part series we focused on publications dealing with positron emission tomography, computed tomography, and magnetic resonance. This review will place emphasis on myocardial perfusion imaging using single-photon emission-computed tomography summarizing advances in the field including in diagnosis, prognosis, and appropriate use.

Cardiac shockwave therapy in patients with chronic refractory angina pectoris

Background

Cardiac shockwave therapy (CSWT) might improve symptoms and decrease ischaemia burden by stimulating collateral growth in chronic ischaemic myocardium. This prospective study was performed to evaluate the feasibility and safety of CSWT.

Methods

We included 33 patients (mean age 70 ± 7 years, mean left ventricular ejection fraction 55 ± 12 %) with end-stage coronary artery disease, chronic angina pectoris and reversible ischaemia on myocardial scintigraphy. CSWT was applied to the ischaemic zones (3–7 spots/session, 100 impulses/spot, 0.09 mJ/mm²) in an echocardiography-guided and ECG-triggered fashion. The protocol included a total of 9 treatment sessions (3 treatment sessions within 1 week at baseline, and after 1 and 2 months). Clinical assessment was performed using exercise testing, angina score (CCS class), nitrate use, myocardial scintigraphy, and cardiac magnetic resonance (CMR) 1 and 4 months after the last treatment session.

Results

One and 4 months after CSWT, sublingual nitrate use decreased from 10/week to 2/week (p < 0.01) and the angina symptoms diminished from CCS class III to CCS class II (p < 0.01). This clinical improvement was accompanied by an improved myocardial uptake on stress myocardial scintigraphy (54.2 ± 7.7 % to 56.4 ± 9.4 %, p = 0.016) and by increased exercise tolerance at 4-month follow-up (from 7.4 ± 2.8 to 8.8 ± 3.6 min p = 0.015). No clinically relevant side effects were observed.

Conclusion

CSWT improved symptoms and reduced ischaemia burden in patients with end-stage coronary artery disease without relevant side effects. The study provides a solid basis for a randomised multicentre trial to establish CSWT as a new treatment option in end-stage coronary artery disease.

Noninvasive Cardiac Imaging in Patients with Known and Suspected Coronary Artery Disease: What is in it for the Interventional Cardiologist?

The long-standing coronary artery disease (CAD) paradigm simplified by the discrimination between patients with or without CAD warrants to be revisited by the insightful information provided by noninvasive cardiac imaging, leading to a comprehensive physiopathological assessment rather than a mainly anatomical approach. This review will address (1) the role of non-invasive cardiac imaging for the appropriate selection of stable patients referred to invasive coronary angiography (ICA), and the evolving concept and prognostic implications of myocardial ischemia; (2) the usefulness of computed tomography coronary angiography for the guidance of percutaneous coronary interventions; and (3) the role and potential clinical impact of novel anatomical and functional non-invasive prognostic markers.