Nonobstructive Coronary Lesions Research Articles

Uncovering a hidden danger: a case report of diffuse coronary spasm concealing spontaneous coronary artery dissection

BackgroundOver recent years, spontaneous coronary artery dissection (SCAD) has emerged as a no longer rare cause of acute coronary syndrome (ACS). On the other hand, coronary artery spasm (CAS) is the main cause of ischemic heart disease with non-obstructive coronary lesions. Clinical manifestations of both vary from stable angina to ACS or, rarely, sudden cardiac death. These entities may be underdiagnosed on a coronary angiography.Case presentationWe report the case of a young woman presenting with acute chest pain and no coronary risk factors. Angiography revealed a focal subcritical stenosis of the right coronary artery. Coronary wiring resulted in diffuse and critical spasm. However, optical coherence tomography (OCT) and intravascular ultrasound (IVUS) showed extensive SCAD. She was therefore treated conservatively. On the fourth day, cardiac computed tomography angiography (CCTA) excluded disease progression, and then she was discharged on medical therapy.ConclusionsCombined IVI plays a vital role in providing accurate and detailed visualization of the coronary anatomy and thus allowing for more precise diagnosis, risk stratification, and treatment planning. CCTA can be considered a valuable tool in the noninvasive follow-up of SCAD.

Prognostic value of negative stress cardiac magnetic resonance imaging in patients with moderate-severe coronary artery stenosis.

This study aims to evaluate the prognostic value of stress cardiac magnetic resonance (CMR) without inducible ischemia in a real-world cohort of patients with known severe coronary artery stenosis. The prognosis of patients with severe coronary artery stenosis and without inducible ischemia using stress CMR remains uncertain, even though its identification of functionally significant coronary artery disease (CAD) is excellent. Patients without inducible ischemia and known CAD who underwent stress CMR between February 2015 and December 2016 were included in this retrospective study. These patients were divided into two groups: group 1 with stenosis of 50%-75% and group 2 with stenosis of >75%. The primary endpoint was defined as the occurrence of a major adverse cardiovascular event (MACE) [cardiac death, non-fatal myocardial infarction (MI), percutaneous coronary intervention (PCI), or coronary artery bypass grafting (CABG)]. Real-world data collected from 169 patients with a median age of 69 (60-75) years were included. The median follow-up was 5.5 (IQR 4.1-6.6) years. Events occurred after a mean time of 3.0 ± 2.2 years in group 1 and 3.7 ± 2.0 years in group 2 (p = 0.35). Sixteen (18.8%) patients in group 1 and 23 (27.4%) patients in group 2 suffered from MACE without a significant difference between the two groups (p = 0.33). In group 2, one cardiac death (1.2%), seven non-fatal MI (8.3%), 15 PCI (17.9%), and one CABG (1.2%) occurred. The findings of this pilot study suggest that long-term outcomes in a real-world patient cohort with known severe and moderate coronary artery stenosis but without inducible ischemia were similar. Stress CMR may provide valuable risk stratification in patients with angiographically significant but hemodynamically non-obstructive coronary lesions.

Небіволол – бета-адреноблокатор з вазодилатаційними властивостями: досягнення і перспективи застосування

Огляд присвячений клінічному застосуванню β-адреноблокатора з вазодилатаційними властивостями – небівололу. Розглянуто основні фармакологічні властивості та характеристики препарату, його кардіоселективність та механізми вазодилатаційної дії. Показано особливості застосування небівололу в лікуванні есенціальної артеріальної гіпертензії, ішемічної хвороби серця та серцевої недостатності. Препарат не має діабетогенної дії при тривалому застосуванні, сприятливо впливає на показники ліпідного та вуглеводного обмінів. У хворих з ішемічною хворобою серця продемонстровано його антиангінальну й антиішемічну дію та зниження частоти рецидивів після виконання операцій на коронарних артеріях. Препарат добре толерується та має високу ефективність у зниженні показників смертності в пацієнтів віком понад 70 років з хронічною серцевою недостатністю, незалежно від фракції викиду лівого шлуночка. У лікуванні ішемічної хвороби серця при цукровому діабеті 2-го типу перевагу надають β-адреноблокаторам з вазодилатаційними властивостями. При необструктивних ураженнях коронарних артерій з-поміж β-адреноблокаторів перевагу надають небівололу для лікування мікросудинної стенокардії. У пацієнтів з артеріальною гіпертензією небіволол, крім антигіпертензивного ефекту, має сприятливий вплив на функцію ендотелію, метаболічний профіль, центральну гемодинаміку, якість життя пацієнтів, а також кращий профіль побічних ефектів.

Current achievements and prospects for the use of nebivolol in the treatment of patients with cardiovascular diseases

A literature review deals with the clinical use of nebivol as a beta-blocker (BB) with vasodilating properties. The principal pharmacological properties and characteristics of the drug, its cardioselectivity and mechanisms of vasodilation are presented. The special place of nebivolol in the treatment of essential arterial hypertension (AH), coronary heart disease (CHD) and heart failure (HF) is outlined. The drug does not possess a diabetogenic activity with a long-term use, and impacts favourably on the parameters of lipid and carbohydrate metabolism. In CHD patients, nebivolol demonstrates the anti-anginal and anti-ischemic activities, and reduces the frequency of angina recurrence after coronary artery interventions. The drug is well tolerated and characterized by a high effectiveness with respect to the reduction of mortality rates in patients with chronic HF over 70 years of age, regardless of the left ventricular ejection fraction. Vasodilating BB are preferred in the treatment of CHD patients with type 2 diabetes. In case of non-obstructive coronary lesions, nebivolol is chosen among existing BBs for the treatment of microvascular angina. The use of nebivolol in AH patients, in addition to the antihypertensive effect, is characterized by a favorable impact on the function of endothelium, the metabolic profile, central hemodynamics, health-related quality of life of patients, as well as more favorable profile of side effects.

Pre-angioplasty instantaneous wave-free ratio pullback predicts hemodynamic outcome in diffuse coronary artery disease

Background: Serial stenoses or diffuse vessel narrowing hamper pressure wire–guided management of coronary stenoses. Characterization of functional relevance of individual stenoses or narrowed segments constitutes an unmet need in ischemia-driven percutaneous revascularization. Aim of the Study: To perform hemodynamic mapping of the entire vessel using pullback technique of a pressure guidewire with continuous instantaneous wave-free ratio (iFR) measurement compared coronary angiography aiming to minimize the procedure, decrease number and length of stents used. Materials and Methods: This study was conducted on 40 patients presented with diffuse coronary artery disease and undergoing elective PCI. Diagnostic coronary angiography using the routine angiographic projections was done with assessment of non-obstructive coronary lesions by 2D quantitative coronary angiography and iFR pullback measurement Results: Percentage of difference between probable sig lesions via pullback technique and No of actual sig lesions for studied group, was (59.5%). The difference was statistically highly significant p=0.0001. Conclusion: Compared with angiography alone, availability of iFR pullback data significantly decreased the number and length of hemodynamically significant lesions identified for revascularization.

Abstract 12511: Differential Regulation of Circulating Damage-Associated Molecular Patterns in Patients With Coronary Artery Ectasia

Introduction: Coronary artery ectasia (CAE) defined as localized or diffuse non-obstructive coronary lesions is a rare but well-recognized pathological entity of the coronary arteries and characterized as a variant of coronary atherosclerosis. CAE commonly coexists with coronary artery disease (CAD). Although inflammation appears to be involved, the pathophysiology behind CAE remains unclear. Danger-associated molecular patterns (DAMPs) are altered metabolism products of necrotic or stressed cells, which are deemed as alarm signals by the innate immune system. Inflammatory agents are DAMP generators and DAMPs create a pro-inflammatory state. Hypothesis: We aimed to investigate the different patterns of serum DAMPs in patients with CAE, obstructive CAD and normal coronary arteries and the prognostic role of these in the pathogenesis of CAE. Methods: In this prospective cross-sectional study, 28 patients with CAE and nonobstructive CAD were enrolled in the study, 19 patients with obstructive CAD but without CAE, and 18 control subjects with normal coronary arteries that have been matched with the CAE patients for age and sex were also enrolled in our study population. Venous blood samples of the participants were collected for serum DAMP evaluation. Results: Patients with CAE and non-obstructive CAD had increased (30-35%) serum levels of the DAMPs, the receptor for advanced glycation end products (RAGE) ligand S100B and the toll-like receptor 4 ligand heat shock protein (HSP)70 compared to control subjects and patients with CAD. Additionally, CAE and non-obstructive CAD patients had decreased (30-40%) serum levels of potential DAMPs, the antioxidant DJ-1 and soluble (s)RAGE, a decoy molecule that bind excess RAGE ligands, compared to control subjects and CAD patients. Positive correlations were observed between S100B and HSP70 (p=00564), and DJ-1 and sRAGE (p=0.00461). All evaluated serum DAMPs were not different in CAD patients compared to control subjects. Conclusion: The differential regulation of the DAMPs S100B, HSP70, DJ-1 and sRAGE in CAE versus CAD makes them attractive novel biomarkers as therapeutic targets and therapeutics.

Atrial Fibrillation and Chronic Kidney Disease-A Risky Combination for Post-Contrast Acute Kidney Injury.

Atrial fibrillation (AF) symptoms may mimic coronary artery disease (CAD) which reflects the difficulties in qualifying AF patients for invasive diagnostics. A substantial number of coronary angiographies may be unnecessary or even put patients at risk of post-contrast acute kidney injury (PC-AKI), especially patients with chronic kidney disease (CKD). We aimed to investigate the hypothesis indicating higher prevalence of PC-AKI in patients with AF scheduled for coronary angiography. The study population comprised of 8026 patients referred for elective coronarography including 1621 with AF. In the comparison of prevalence of PC-AKI in distinguished groups we can see that kidney impairment was twice more frequent in patients with AF in both groups with CKD (CKD (+)/AF (+) 6.24% vs. CKD (+)/AF (−) 3.04%) and without CKD (CKD (−)/AF (+) 2.32% vs. CKD (−)/AF (−) 1.22%). In our study, post-contrast acute kidney disease is twice more frequent in patients with AF, especially in subgroup with chronic kidney disease scheduled for coronary angiography. Additionally, having in mind results of previous studies stating that AF is associated with non-obstructive coronary lesions on angiography, patients with AF and CKD may be unnecessarily exposed to contrast agent and possible complications.

Prognostic Implication of Non-Obstructive Coronary Lesions: A New Classification in Different Settings.

The clinical significance of non-obstructive coronary artery disease is the subject of debate. Our objective was to evaluate the long-term cardiovascular prognosis associated with non-obstructive coronary artery disease in patients undergoing coronary angiography, and to conduct a stratification by sex, diabetes, and clinical indication. We designed a multi-centre retrospective longitudinal observational study of 3265 patients that were classified into three groups: normal coronary arteries (lesion <20%, 1426 patients), non-obstructive coronary artery disease (20–50%, 643 patients), and obstructive coronary artery disease (>70%, 1196 patients). During a mean follow-up of 43 months, we evaluated a combined cardiovascular event: acute myocardial infarction, stroke, hospitalization for heart failure, or cardiovascular death. Multivariable-adjusted Cox proportional hazard models showed a worse prognosis in patients with non-obstructive coronary artery disease, in comparison with patients of normal coronary arteries group, in the total population (hazard ratio 1.72, 95% confidence interval 1.23–2.39; p for trend <0.001), in non-diabetics (hazard ratio 2.12, 95% confidence interval: 1.40–3.22), in women (hazard ratio 1.75, 95% confidence interval 1.10–2.77), and after acute coronary syndrome (hazard ratio 2.07, 95% confidence interval 1.25–3.44). In conclusion, non-obstructive coronary artery disease is associated with an impaired long-term cardiovascular prognosis. This association held for non-diabetics, women, and after acute coronary syndrome.

The relationship between serum magnesium level and coronary artery ectasia .

Background: Magnesium is an essential element that plays a crucial role in cardiac and vascular functions. Low levels of intracellular (Mg2+) lead to abnormal vascular cell growth, inflammation, fibrosis resulting in negative vascular remodeling, finally results in CAE. Objective: The aim of this study was to studying serum magnesium level among patients going to do elective coronary angiography for comparing its level in O- CAD patients , and CAE patients , and arelationship between serum magnesium level and CAE . Methods: A case control study was conducted on 84 patients admitted for elective CA for suspected ischemic heart disease. The patients were divided into 4 groups according to CA results. All patients were subjected to detailed history, physical examination, electrocardiography, conventional echocardiography, laboratory investigations and coronary angiography. Results: 84 patients divided into 4 groups, patients with obstructive coronary artery disease (group I), isolated coronary artery ectasia (group II), normal coronaries (group III) and patients with coronary artery ectasia and obstructive coronary artery disease (group IV). A significant correlation was found as regarding serum Mg in between one another group with significant p values, except for comparing group I (obstructive coronary artery disease) with group III (normal coronaries) there was no statistically significant difference in between them with p value 0.984, with best cut-off value considering prediction of CAE >1.8 with 80.95% sensitivity and 71.43% specificity. Conclusion: (Mg2+) level is highly predictive in suspecting the finding of coronary artery ectasia in both obstructive and non-obstructive coronary lesions.

High-risk plaque regression after intensive dietary intervention in patients with non-obstructive coronary artery disease: a randomised computed tomography angiography study (DISCO-CT)

Abstract Background Lifestyle and diet modification are the forefront in the management of coronary artery disease (CAD), however, there is no data whether they may stop progression of atheroslcerosis. Some coronary plaque characteristics are known to increase the risk of future cardiovascular events independently of coronary stenosis severity. These plaques are characterized by the presence of lipids and necrotic elements, and can be identified with coronary computed tomography angiography (CTA). Purpose To study the effect of intensive dietary intervention on changes in atherosclerotic plaque volume and composition. Methods We enrolled 89 patients (41% women, mean age 60±7.7 years) with nonobstructive coronary lesions (&amp;lt;70% stenosis) identified by CTA (2x192-multislice scanner, temporal resolution 66 ms), qualified to medical treatment. All participants were subjected to optimal medical therapy (OMT). Patients were randomised (1:1) to either A) OMT with regular follow-up (after 1, 3, 6, 9 and 12 months) by a dietitian to stick to Dietary Approaches to Stop Hypertension (DASH) model, or B) routine management, ie. OMT alone. CTA was repeated in all patients after the mean time of 66.9±13.7 weeks. An experienced observer blinded to the allocated treatment group and other clinical data evaluated all of the scans. The outcome was change in total plaque volume, percent plaque volume and plaque composition, assessed with a dedicated software system. Based on tissue attenuation ranges in Hounsfield units (HU), the following components of atheroma were distinguished: dense calcium (&amp;gt;351 HU), fibrous plaque (151 to 350 HU), and fibrofatty plaque plus necrotic core (−100 to 150 HU), regarded as the vulnerable plaque component. Results Total plaque volume did not change significantly in any group (p=0.41; Figure 1A). Percent atheroma volume increased in the control arm vs. no significant change in the experimental arm, with no significant intergroup difference (p=0.79; Figure 1B). Vulnerable plaque component decreased in both subgroups, by 52.9±82.2 mm3 in the experimental vs. 20.8±58.5 mm3 in the control arm, and there was a significant difference in the reductions between the groups (p=0.04; Figure 1C). Fibrous plaque volume and dense calcium volume did not change significantly in any group (+9.5±117.8 mm3 in the experimental vs. +7.6±92.1 mm3 in the control arm, p=0.93, and +33±68.9 mm3 vs. +30.2±52.5 mm3, p=0.78, respectively). Conclusions Intensive diet intervention atop OMT can stop the progression of atherosclerosis and lead to a significant reduction in vulnerable plaque component compared to OMT alone. Figure 1 Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Institute of Cardiology in Warsaw, Poland

Atrial fibrillation is more frequently associated with nonobstructive coronary lesions: the Bialystok Coronary Project.

Atrial fibrillation (AF) and chronic coronary syndrome (CCS) share common risk factors and frequently coexist. Additionally, AF symptoms may mimic CCS. The aim of the study was to investigate the hypothesis indicating absence of significant coronary lesions in patients with AF as compared with those with sinus rhythm. We conducted a single‑center retrospective study including consecutive patients referred for elective coronary angiography between 2007 and 2016. The study population included 8288 patients out of whom 1674 had AF. There were substantial differences between groups with and without AF. Patients with AF were significantly older, more often were men and had diabetes, and more frequently were diagnosed with both chronic kidney disease and heart failure. On the other hand, they had history of hyperlipidemia less often. CCS was less frequently detected in patients with AF as compared with those with sinus rhythm (37.5% vs 41.1%; P <0.001). Additionally, the latter group more often underwent subsequent coronary angioplasty (19.2% vs 22.3%; P = 0.004). Multivariable analysis identified AF as an independent factor associated with absence of significant coronary lesions (odds ratio, 1.57; 95% CI, 1.32-1.87; P <0.001). Moreover, a comparison between patients with and without angiographically significant CCS revealed a higher prevalence of AF in the latter group (18.7% vs 21.2%; P = 0.006). In our study, AF was associated with the absence of significant coronary lesions on angiography, reflecting difficulties with qualifying patients with AF for invasive CCS diagnostic workup. Our findings suggest the need for more efficacious noninvasive diagnostic approach for patients with AF and suspected CCS.

Acute myocardial infarction in libyan patients below 45 years of age: Prevalence and risk factors

Background and Aims: Acute myocardial infarction (AMI) below 45 years of age constitutes a specific subset of population having different risk factors and clinical features as compared to older patients. The aim of the study was to assess the frequency and risk factors of AMI in patient's ≤45 years of age.Patients and Methods: A cross-sectional retrospective study was conducted involving 187 patients with clinical diagnosis of AMI. They were studied for risk factors, clinical characteristics, coronary angiographic finding and in-hospital outcome during January 2015 and December 2015 at Benghazi medical center, Benghazi - Libya. Results: Out of total 187 AMI patients studied, there were 41 (22%) young patient ≤45 years of age. Risk factors was studied, smoking was found in 63.4% of young patients, 44% were had history of dyslipidemia, 14% had history of alcohol drinking and 12% had family history of coronary artery disease. In young AMI patients, anterior wall STEMI was the most common site and single vessel disease was the most common finding in coronary angiography. However, 13% of patients have normal or non-obstructive coronary lesions. Arrhythmia (24%) and heart failure (17%).Conclusion: In our young AMI patients, smoking was the single most important modifiable risk factor, other conventional risk factors are less strongly associated than older patients. Our young patients tend to have less extensive coronary artery lesions. The presence of normal or non-obstructive coronary lesions would suggest possibility of different mechanism of myocardial necrosis.

Exercise Electrocardiography Testing in Patients with Calcific Non-obstructive Coronary Lesions at Cardiac Multislice Computed Tomography

Background: Non-obstructive coronary artery disease (NoCAD), cardiac syndrome X (CSX), conduit vessel endothelial dysfunction and microvascular angina are all terms used to describe patients that have chest pain yet no obstructive coronary artery disease on coronary angiography. Objectives: the purpose of this study was to evaluate exercise ECG (Ex-ECG) test in patients with subclinical atherosclerosis who were diagnosed by multi-slice computed tomography (MSCT) coronary angiography to have nonobstructive lesions. Patients and Methods: 100 patients were recruited in the current study (their age ranged from 30 – 66 years), they were classified into three groups: group (A) 30 patients with non-calcific normal coronaries by MSCT, group (B) 35 patients with non-calcific non-obstructive lesions (zero calcium score) by MSCT and group (C) 35 patients with calcific non-obstructive lesions (calcium score < 400 HU) by MSCT. Results: There was statistically highly significant difference between the three groups as regard results of exercise ECG test (P value=0.001). Positive exercise ECG test results occurred with calcific and mixed plaques in group (C) more than soft plaque in group (B), and there is significant difference between two groups with (P-value = 0.001). Positive exercise ECG test results in group (C) occurred more frequently with higher calcium score ranged from (59 – 362) HU. Conclusions: MSCT angiography and calcium scoring system can provide valuable results which is helpful in avoiding an extra unnecessary invasive coronary angiography in patients for whom exercise ECG test results seemed to be positive or for whom high cardiovascular mortality risk from ischemia is not present.

Exercise Electrocardiography Testing in Patients with Calcific Non-obstructive Coronary Lesions at Cardiac Multislice Computed Tomography

Background: Non-obstructive coronary artery disease (NoCAD), cardiac syndrome X (CSX), conduit vessel endothelial dysfunction and microvascular angina are all terms used to describe patients that have chest pain yet no obstructive coronary artery disease on coronary angiography. Objectives: the purpose of this study was to evaluate exercise ECG (Ex-ECG) test in patients with subclinical atherosclerosis who were diagnosed by multi-slice computed tomography (MSCT) coronary angiography to have nonobstructive lesions. Patients and Methods: 100 patients were recruited in the current study (their age ranged from 30 – 66 years), they were classified into three groups: group (A) 30 patients with non-calcific normal coronaries by MSCT, group (B) 35 patients with non-calcific non-obstructive lesions (zero calcium score) by MSCT and group (C) 35 patients with calcific non-obstructive lesions (calcium score < 400 HU) by MSCT. Results: There was statistically highly significant difference between the three groups as regard results of exercise ECG test (P value=0.001). Positive exercise ECG test results occurred with calcific and mixed plaques in group (C) more than soft plaque in group (B), and there is significant difference between two groups with (P-value = 0.001). Positive exercise ECG test results in group (C) occurred more frequently with higher calcium score ranged from (59 – 362) HU. Conclusions: MSCT angiography and calcium scoring system can provide valuable results which is helpful in avoiding an extra unnecessary invasive coronary angiography in patients for whom exercise ECG test results seemed to be positive or for whom high cardiovascular mortality risk from ischemia is not present.

Role of clinical evaluation in the identification of coronary obstructive disorders in patients with stable coronary artery disease. Part I

To make a decision on choice the type of myocardial revascularization in patients with coronary artery disease (CAD), an invasive coronary angiography (CAG) is necessary. However, in clinical practice, a significant number of patients during CAG fails to detect coronary obstructive disorders, there is the so-called problem of “clean” coronary arteries. Indeed, in the Russian Federation in approximately 50% of cases, CAG does not end with myocardial revascularization, and in patients with suspected CAD, non-obstructive coronary artery lesions are detected in 67% of cases. In the first part of the review, a critical analysis of the clinical evaluation of patients in the selection of patients for CAG was conducted. First stages of the diagnostic process based on clinical evaluation are considered. The review discusses the use for diagnostic purposes more complete set of routine assessment methods and the expanded use of laboratory tests using memetic algorithms.

Relevance of anatomical, plaque, and hemodynamic characteristics of non-obstructive coronary lesions in the prediction of risk for acute coronary syndrome.

We explored the anatomical, plaque, and hemodynamic characteristics of high-risk non-obstructive coronary lesions that caused acute coronary syndrome (ACS). From the EMERALD study which included ACS patients with available coronary CT angiography (CCTA) before the ACS, non-obstructive lesions (percent diameter stenosis < 50%) were selected. CCTA images were analyzed for lesion characteristics by independent CCTA and computational fluid dynamics core laboratories. The relative importance of each characteristic was assessed by information gain. Of the 132 lesions, 24 were the culprit for ACS. The culprit lesions showed a larger change in FFRCT across the lesion (ΔFFRCT) than non-culprit lesions (0.08 ± 0.07 vs 0.05 ± 0.05, p = 0.012). ΔFFRCT showed the highest information gain (0.051, 95% confidence interval [CI] 0.050-0.052), followed by low-attenuation plaque (0.028, 95% CI 0.027-0.029) and plaque volume (0.023, 95% CI 0.022-0.024). Lesions with higher ΔFFRCT or low-attenuation plaque showed an increased risk of ACS (hazard ratio [HR] 3.25, 95% CI 1.31-8.04, p = 0.010 for ΔFFRCT; HR 2.60, 95% CI 1.36-4.95, p = 0.004 for low-attenuation plaque). The prediction model including ΔFFRCT, low-attenuation plaque and plaque volume showed the highest ability in ACS prediction (AUC 0.725, 95% CI 0.724-0.727). Non-obstructive lesions with higher ΔFFRCT or low-attenuation plaque showed a higher risk of ACS. The integration of anatomical, plaque, and hemodynamic characteristics can improve the noninvasive prediction of ACS risk in non-obstructive lesions. • Change in FFR CT across the lesion (ΔFFR CT ) was the most important predictor of ACS risk in non-obstructive lesions. • Non-obstructive lesions with higher ΔFFR CT or low-attenuation plaque were associated with a higher risk of ACS. • The integration of anatomical, plaque, and hemodynamic characteristics can improve the noninvasive prediction of ACS risk.

Noninvasive Derivation of Fractional Flow Reserve From Coronary Computed Tomographic Angiography: A Review.

Coronary computed tomographic angiography (CCTA) has evolved as a rapid and highly sensitive method for the exclusion of obstructive coronary artery disease. Unfortunately, as it pertains to moderate and severe lesions, the ability to discriminate between those that are hemodynamically significant and those that are nonobstructive is lacking. Consequently, this deficiency can result in a significant number of unnecessary referrals for invasive angiography that yields nonobstructive results. Fractional flow reserve (FFR), which assesses the hemodynamic significance of a specific lesion, when performed during invasive angiography, results in improved patient outcomes compared with visual stenosis assessment alone. Through the application of computational analytic methods to CT-derived anatomic coronary models, noninvasive calculation of FFR has become possible. This allows for the improved ability to differentiate between nonobstructive coronary lesions and those that are truly hemodynamically significant. Currently, HeartFlow FFRCT is the only FDA-approved and commercially available CCTA-derived FFR (CT-FFR) platform. By reducing the number of invasive procedures performed for nonobstructive disease, CT-derived FFR has the ability to lower health care expenditures and become the true gatekeeper to invasive angiography.

Structured learning algorithm for detection of nonobstructive and obstructive coronary plaque lesions from computed tomography angiography.

Visual identification of coronary arterial lesion from three-dimensional coronary computed tomography angiography (CTA) remains challenging. We aimed to develop a robust automated algorithm for computer detection of coronary artery lesions by machine learning techniques. A structured learning technique is proposed to detect all coronary arterial lesions with stenosis [Formula: see text]. Our algorithm consists of two stages: (1)two independent base decisions indicating the existence of lesions in each arterial segment and (b) the final decision made by combining the base decisions. One of the base decisions is the support vector machine (SVM) based learning algorithm, which divides each artery into small volume patches and integrates several quantitative geometric and shape features for arterial lesions in each small volume patch by SVM algorithm. The other base decision is the formula-based analytic method. The final decision in the first stage applies SVM-based decision fusion to combine the two base decisions in the second stage. The proposed algorithm was applied to 42 CTA patient datasets, acquired with dual-source CT, where 21 datasets had 45 lesions with stenosis [Formula: see text]. Visual identification of lesions with stenosis [Formula: see text] by three expert readers, using consensus reading, was considered as a reference standard. Our method performed with high sensitivity (93%), specificity (95%), and accuracy (94%), with receiver operator characteristic area under the curve of 0.94. The proposed algorithm shows promising results in the automated detection of obstructive and nonobstructive lesions from CTA.

Atherosclerotic plaque characteristics improve diagnosis of ischemia for non-obstructive coronary artery lesions: a direct comparison to fractional flow reserve

Purpose: Fractional flow reserve (FFR) at the time of invasive coronary angiography (ICA) is the gold standard for determining lesion-specific ischemia, and identifies ischemia in a significant proportion of lesions considered anatomically non-obstructive. Beyond luminal stenosis severity, coronary CT angiography (CT) enables evaluation of atherosclerotic plaque characteristics (APCs) that include positive remodeling (PR), low attenuation plaque (LAP) and spotty intra-plaque calcification (SC). The relationship of these APCs to ischemia in non-obstructive coronary lesions has not been evaluated to date. Methods: 252 patients from 17 centers in 5 countries were prospectively enrolled. Patients underwent CT and ICA, with clinically indicated FFR performed for 407 coronary lesions. CTs were evaluated by an independent core laboratory in blinded fashion, with ≥50% and <50% stenosis considered obstructive and non-obstructive, respectively. Presence of APCs within coronary lesions by CT was defined as: (1) PR, maximal lesion diameter/reference diameter ≥1.10; (2) LAP, any intra-plaque voxel <30 HU; and (3) SC, nodular calcified plaque ≤3 mm. Coronary lesion-specific ischemia was defined by an FFR ≤0.8. Results: For FFR-interrogated coronary lesions, 195 of 407 (48%) were non-obstructive by CT. FFR-defined ischemia was present in 33 of 195 (17%) lesions, with a mean FFR value of 0.75±0.07. Amongst non-obstructive lesions that caused ischemia, 24 (73%), 9 (27%) and 8 (24%) exhibited PR, LAP and SC, respectively; with at least 1 APC present in 24 (73%) of lesions. In multivariable analyses, the presence of PR [Odds ratio (OR) 6.6, 95% confidence interval (CI) 2.4-17.9, p<0.0001)] was associated with lesion-specific ischemia while LAP (OR 1.0, 95% CI 0.3-3.2, p=0.9) and SC (OR 1.4, 95% CI 0.5-4.5, p=0.5) were not. A dose-response relationship was observed for increasing risk of ischemia for non-obstructive coronary lesions possessing 1 (OR 4.5, p=0.006), 2 (OR 11.8, p<0.001) and 3 (OR 4.0, p=0.1) APCs. Conclusion: The presence of positive arterial remodeling and increasing numbers of APCs enhances diagnosis of non-obstructive coronary lesions that cause ischemia.

Nonobstructive coronary disease leading to STEMI

Nonobstructive coronary atherosclerotic lesions can lead to ST-elevation myocardial infarction (STEMI). Thrombus aspiration during a primary percutaneous coronary intervention provides a setting to evaluate the degree of stenosis of culprit lesions leading to STEMI. The aim of this study was to assess the degree of culprit lesion residual stenosis after thrombus aspiration and to compare the demographic, clinical, and angiographic characteristics between patients with obstructive versus nonobstructive residual stenosis. From a single-center registry of 483 consecutive patients with STEMI undergoing a primary percutaneous coronary intervention, 172 patients underwent thrombus aspiration and were eligible for our study. We defined two groups according to the residual stenosis after thrombus aspiration: group A (n=119, 69%) with residual stenosis greater than or equal to 50%, and group B (n=53, 31%) with residual stenosis less than 50%.In terms of the baseline angiographic characteristics, patients with residual stenosis less than 50% had significantly lower prevalence of multivessel disease (15.1 vs. 46.2%, P<0.001). On multivariable analysis of the preprocedural variables, absence of vascular disease (odds ratio 4.99, 95% confidence interval 1.08-23.12, P=0.040) and age less than 59 years (odds ratio 2.67, 95% confidence interval 1.25-5.73, P=0.011) were independent predictors of culprit residual stenosis less than 50%. In this population, a significant proportion of patients with STEMI had nonobstructive residual stenosis after thrombus aspiration. These patients were younger, had a lower prevalence of vascular disease in other vascular territories, and less multivessel disease, suggesting an earlier stage of atherosclerosis.