Fractional flow reserve derived from CCTA may have a prognostic role in myocardial bridging

Predictors of discordance between CT-derived fractional flow reserve (CT-FFR) and △CT-FFR in deep coronary myocardial bridging

OBJECTIVE

To compare the performance between CT-derived fractional flow reserve (CT-FFR) and ΔCT-FFR measurements in patients with deep myocardial bridging (MB) along the left anterior descending artery, and explore the potential predictors of discordance.

METHODS

175 patients with deep MB who underwent coronary computed tomography angiography (CCTA) and CT-FFR assessment were included. Clinical, anatomical and atherosclerotic variables were compared between patients with concordant and discordant CT-FFR and ΔCT-FFR.

RESULTS

30.9 % patients were discordantly classified, in which 94.4 % patients were classified as CT-FFR+/△CT-FFR-. The discordant group showed significantly higher upstream stenosis degree, distance from MB to the aorta, △CT-FFR (P 0.007, 0.009 and 0.002, respectively), and lower CT-FFR (P < 0.001). In multivariate analysis, upstream stenosis degree (P 0.023, OR 1.628, 95 % CI: 1.068-2.481) and distance from MB to the aorta (P 0.001, OR 1.04, 95 % CI: 1.016-1.064) were independent predictors for discordance between CT-FFR and ΔCT-FFR.

CONCLUSION

The discordance between CT-FFR and ΔCT-FFR measurements underscores the challenges in clinical decision-making, necessitating tailored approaches for MB evaluation.

Coronary CTA-based vascular radiomics predicts atherosclerosis development proximal to LAD myocardial bridging

AIMS

Cardiac cycle morphological changes can accelerate plaque growth proximal to myocardial bridging (MB) in the left anterior descending artery (LAD). To assess coronary computed tomography angiography (CCTA)-based vascular radiomics for predicting proximal plaque development in LAD MB.

METHODS AND RESULTS

Patients with repeated CCTA scans showing LAD MB without proximal plaque in index CCTA were included from Jinling Hospital as a development set. They were divided into training and internal testing in an 8:2 ratio. Patients from four other tertiary hospitals were set as external validation set. The endpoint was proximal plaque development of LAD MB in follow-up CCTA. Four vascular radiomics models were built: MB centreline (MB CL), proximal MB CL (pMB CL), MB cross-section (MB CS), and proximal MB CS (pMB CS), whose performances were evaluated using area under the receiver operating characteristic curve (AUC), integrated discrimination improvement (IDI), and net reclassification improvement (NRI). In total, 295 patients were included in the development (n = 192; median age, 54 ± 11 years; 137 men) and external validation sets (n = 103; median age, 57 ± 9 years; 57 men). The pMB CS vascular radiomics model exhibited higher AUCs in training, internal test, and external sets (AUC = 0.78, 0.75, 0.75) than the clinical and anatomical model (all P < 0.05). Integration of the pMB CS vascular radiomics model significantly raised the AUC of the clinical and anatomical model from 0.56 to 0.75 (P = 0.002), along with enhanced NRI [0.76 (0.37-1.14), P < 0.001] and IDI [0.17 (0.07-0.26), P < 0.001] in the external validation set.

CONCLUSION

The CCTA-based pMB CS vascular radiomics model can predict plaque development in LAD MB.

Quantitative computed tomography angiography evaluation of the coronary fractional flow reserve in patients with left anterior descending artery myocardial bridging

PURPOSE

To quantitatively investigate the effect of myocardial bridge (MB) in the left anterior descending artery (LAD) on the fractional flow reserve (FFR).

MATERIALS AND METHODS

Three-hundred patients with LAD MB who had undergone coronary artery CT angiography (CCTA) were retrospectively enroled, and 104 normal patients were enroled as the control. The CCTA-derived fractional flow reserve (FFRCT) was measured at the LAD 10 mm proximal (FFR1) and 20-40 mm distal (FFR3) to the MB and at the MB location (FFR2).

RESULTS

FFR2 and FFR3 of the MB (with BM only) and MBLA (with both MB and atherosclerosis) groups were significantly (p < 0.01) lower than those of the control. The FFR3 distal to the MB was significantly lower (p < 0.01) than that of the control. The FFRCT of the whole LAD in the MBLA group was significantly (p < 0.05) lower than that of the MB and control group (p < 0.05). MB length (OR 1.061) and MB muscle index (odds ratio or OR 1.007) were two risk factors for abnormal FFRCT, and MB length was a significant independent risk factor for abnormal FFRCT (OR = 1.077). LAD stenosis degree was a risk factor for abnormal FFRCT values (OR 3.301, 95% confidence interval [CI] 1.441-7.562, p = 0.005) and was also a significant independent risk factor (OR = 3.369, 95% CI: 1.392-8.152; p = 0.007) for abnormal FFRCT.

CONCLUSION

MB significantly affects the FFRCT of distal coronary artery. For patients with MB without atherosclerosis, the MB length is a risk factor significantly affecting FFRCT, and for patients with MB accompanied by atherosclerosis, LAD stenotic severity is an independent risk factor for FFRCT.

Non-Invasive Assessment of Endothelial Shear Stress in Myocardial Bridges Using Coronary Computed Tomography Angiography

Myocardial bridging (MB) is a segment of coronary arteries with an intramural course, typically spared from atherosclerosis, while the adjacent proximal segment is reported to be atherosclerosis-prone, a phenomenon contributed to local endothelial shear stress (ESS). We aimed to describe the ESS milieu in coronaries with MBs combining coronary computed tomography angiography with computational fluid dynamics and to investigate the association of atherosclerosis presence proximal to MBs with hemorheological characteristics. Patients (n = 36) were identified and 36 arteries with MBs (11 deep and 25 superficial) were analyzed. ESS did not fluctuate 5 mm proximally to MBs vs 5 mm within MBs (0.94 vs 1.06 Pa, p = .56). There was no difference when comparing ESS in the proximal versus mid versus distal MB segments (1.48 vs 1.37 vs 1.9 Pa, p = ns). In arteries with plaques (n = 12), no significant ESS variances were observed around the MB entrance, when analyzing all arteries (p = .81) and irrespective of morphological features of the bridged segment (deep MBs; p = .65, superficial MBs; p = .84). MBs are characterized by homogeneous, atheroprotective ESS, possibly explaining the absence of atherosclerosis within bridged segments. The interplay between ESS and atherosclerosis is potentially not different in arteries with MB compared with arteries without bridges.

Effect of a second-generation motion correction algorithm on image quality and measurement reproducibility of coronary CT angiography in patients with a myocardial bridge and mural coronary artery

AIM

To determine the effect of second-generation motion correction (MC2) on image quality and measurement reproducibility of cardiac CT images in patients with a myocardial bridge and mural coronary artery (MB-MCA) compared to standard (STD) images without motion correction and with first-generation motion correction (MC1).

MATERIALS AND METHODS

A total of 66 patients with MB-MCA in the left anterior descending branch who underwent 256-detector CT with single-heartbeat acquisition were included. Images were reconstructed at 45% and 75% R-R intervals using STD, MC1, and MC2 algorithms. Image quality for MB-MCA was assessed by two observers on a four-point scale (1 = poor and 4 = excellent) and compared among STD, MC1, and MC2. Depth and length of MB, lumen area, and minimal diameter of MCA were measured and compared.

RESULTS

At 45% R-R interval, image quality scores were 1.59 ± 0.78, 2.21 ± 0.97, and 3.21 ± 0.62 for MCA, and 2.48 ± 0.79, 2.76 ± 0.75, and 3.58 ± 0.58 for MB with STD, MC1 and MC2, respectively. At 75% R-R interval, these values were 2.26 ± 0.60, 3.03 ± 0.89, and 3.59 ± 0.55 for MCA and 3.00 ± 0.93, 3.17 ± 0.83, and 3.80 ± 0.44 for MB. Although MC1 was superior to STD in displaying MCA, there was no statistical difference between the two algorithms for MB (p>0.05). Compared with STD and MC1, MC2 statistically improved image quality and interpretability for both MCA and MB and had narrower limits in interobserver agreement for measurements at both 45% and 75% R-R intervals.

CONCLUSION

MC2 improves CT image quality and measurement reproducibility in patients with MB-MCA compared to STD and MC1.

Myocardial Bridging: Review on the Role of Coronary Computed Tomography Angiography

Myocardial bridging (MB) is a congenital coronary anomaly in which a segment of a coronary artery, most frequently the left anterior descending artery, deviates from its epicardial route by passing through the myocardium. The advent of cardiac computed tomography angiography (CCTA), equipped with its multiplane and three-dimensional functionalities, has notably enhanced the ability to identify MBs. Furthermore, novel post-processing methods have recently emerged to extract functional insights from anatomical evaluations. MB is generally considered a benign entity with very good survival rates; however, there is an increasing volume of evidence that certain MB characteristics may be associated with cardiovascular morbidity. This review is intended to depict the diagnostic and prognostic role of CCTA in the MB context.

Nomogram to predict recurrent chest pain in patients with myocardial bridging

OBJECTIVE

Patients with myocardial bridging (MB) frequently experience recurrent chest pain, even in those without coronary heart disease. This study aims to predict the risk of recurrent chest pain in patients with MB by using a novel predictive nomogram.

METHODS

This retrospective study enrolled 250 patients with acute chest pain who underwent coronary computed tomography angiography (CCTA) between January and December 2018, including 111 patients with MB and 139 control patients. Least absolute shrinkage and selection operator (LASSO) and multivariable Cox regression analyses were used to screen for significant parameters that were included to develop a novel predictive nomogram model. Receiver operating characteristic curve, calibration curve, and decision curve analyses were used to evaluate the performance and clinical utility of the nomogram.

RESULTS

A predictive nomogram was constructed in 111 patients with MB, 34 of whom (30.9%) had recurrent chest pain. The significant predictors screened out by the LASSO regression included age, sex, branch type MB, and systolic compression index. The area under the curves (AUCs) for recurrent chest pain at 12, 24, and 36 months were 0.688, 0.742, and 0.729, respectively, indicating remarkable accuracy of the nomogram. The calibration curve and decision curve analyses indicated a good agreement with the observations and utility of the nomogram.

CONCLUSIONS

This study presents a high-accuracy nomogram to predict recurrent chest pain in patients with MB. This model incorporates clinical risk factors and CT imaging features and can be conveniently used to facilitate the individualised prediction.

KEY POINTS

• Symptomatic patients with myocardial bridging often present with recurrent chest pain. • The potential predictors of recurrent chest pain in patients with myocardial bridging were age, sex, branch type MB, and systolic compression index. • Nomogram based on clinical CT imaging features is valuable to predict recurrent chest pain in patients with myocardial bridging.

Assessment of myocardial bridging and the pericoronary fat attenuation index on coronary computed tomography angiography: predicting coronary artery disease risk

BACKGROUND

The fat attenuation index (FAI) is a radiological parameter that represents pericoronary adipose tissue (PCAT) inflammation, along with myocardial bridging (MB), which leads to pathological shear stress in the coronary vessels; both are associated with coronary atherosclerosis. In the present study, we assessed the predictive value of FAI values and MB parameters through coronary computed tomography angiography (CCTA) for predicting the risk of coronary atherosclerosis and vulnerable plaque in patients with MB.

METHODS

We included 428 patients who underwent CCTA and were diagnosed with MB. FAI values, MB parameters, and high-risk coronary plaque (HRP) characteristics were recorded. The subjects were classified into two groups (A and B) according to the absence or presence of coronary plaque in the segment proximal to the MB. Group B was further divided into Groups B₁ (HRP-positive) and B₂ (HRP-negative) according to the HRP characteristic classification method. The differences among the groups were analysed. Multiple logistic regression analysis was performed to determine the independent correlation between FAI values and MB parameters and coronary atherosclerosis and vulnerable plaque risk.

RESULTS

Compared to the subjects in Group A, those in Group B presented greater MB lengths, MB depths and muscle index values, more severe MB systolic stenosis and higher FAI_lesion values (all P < 0.05). In multivariate logistic analysis, age (OR 1.076, P < 0.001), MB systolic stenosis (OR 1.102, P < 0.001) and FAI_lesion values (OR 1.502, P < 0.001) were independent risk factors for the occurrence of coronary atherosclerosis. Compared to subjects in Group B₂, those in Group B₁ presented greater MB lengths and higher FAI values (both P < 0.05). However, only the FAI_lesion value was an independent factor for predicting HRP (OR 1.641, P < 0.001).

CONCLUSION

In patients with MB, MB systolic stenosis was associated with coronary plaque occurrence in the segment proximal to the MB. The FAI value was not only closely related to coronary atherosclerosis occurrence but also associated with plaque vulnerability. FAI values may provide more significant value in the prediction of coronary atherosclerosis than MB parameters in CCTA.

Coronary Computed Tomography Angiography-derived Fractional Flow Reserve: An Expert Consensus Document of Chinese Society of Radiology

Invasive fractional flow reserve (FFR) measured by a pressure wire is a reference standard for evaluating functional stenosis in coronary artery disease. Coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) uses advanced computational analysis methods to noninvasively obtain FFR results from a single conventional coronary computed tomography angiography data to evaluate the hemodynamic significance of coronary artery disease. More and more evidence has found good correlation between the results of noninvasive CT-FFR and invasive FFR. CT-FFR has proven its potential in optimizing patient management, improving risk stratification and prognosis, and reducing total health care costs. However, there is still a lack of standardized interpretation of CT-FFR technology in real-world clinical settings. This expert consensus introduces the principle, workflow, and interpretation of CT-FFR; summarizes the state-of-the-art application of CT-FFR; and provides suggestions and recommendations for the application of CT-FFR with the aim of promoting the standardized application of CT-FFR in clinical practice.

The role of cardiac computed tomography in sports cardiology: back to the future!

In recent years, the role of pre-participation evaluation (PPE) in the prevention of sudden cardiac death in competitive athletes has become evident. Most physicians routinely supplement assessment by resting electrocardiogram with imaging techniques, such as echocardiography. The primary goal of imaging in the clinical assessment of competitive athletes is to exclude cardiovascular conditions associated with adverse outcomes. Cardiac computed tomography is emerging as an important technique for stratifying cardiovascular risk and assessing coronary artery disease (CAD), particularly in master athletes. Conversely, in young athletes, this technique has the best non-invasive coronary artery resolution and provides valuable details on coronary artery anatomy. Recent technical developments have brought about a dramatic reduction in radiation exposure, a major drawback of this diagnostic method; nowadays cardiac computed tomography may be performed at a dose of barely one millisievert. The present review provides a practical guide for the use of cardiac computed tomography in the PPE of competitive athletes, with a specific focus on its value for detecting congenital coronary anomalies and CAD in young and master athletes, respectively.

'A bridge over troubled water': a case report

Background

Myocardial bridge (MB) is the most common inborn coronary artery variant, in which a portion of myocardium overlies a major epicardial coronary artery segment. Myocardial bridge has been for long considered a benign condition, although it has been shown to cause effort-related ischaemia.

Case summary 

We present the case of a 17-year-old female patient experiencing chest pain during physical activity. Since her symptoms became unbearable, electrocardiogram and echocardiography were performed together with a coronary computed tomography scan, revealing an MB on proximal-mid left anterior descending artery. In order to unequivocally unmask the ischaemic burden lent by MB, the patient underwent coronary angiography and physiological invasive test: instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) were calculated, both at baseline and after dobutamine infusion (5 µg/kg/min). At baseline, iFR value was borderline (= 0.89), whereas after dobutamine infusion and increase in the heart rate, the patient suffered chest pain. This symptom was associated with a decrease in the iFR value up to 0.77. Consistently, when FFR was performed, a value of 0.92 was observed at baseline, while after inotrope infusion the FFR reached the haemodynamic significance (= 0.79). Therefore, a medical treatment with bisoprolol was started.

Discussion 

Our clinical case shows the importance of a comprehensive non-invasive and invasive assessment of MB in young patients experiencing chest pain, with significant limitation in the daily life. The coronary functional indexes allow to detect the presence of MB-derived ischaemia, thus guiding the decision to undertake a medical/surgical therapy.

Diagnostic Performance of Machine Learning Based CT-FFR in Detecting Ischemia in Myocardial Bridging and Concomitant Proximal Atherosclerotic Disease

BACKGROUND

The diagnostic performance of coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) in detecting ischemia in myocardial bridging (MB) has not been investigated to date.

METHODS

This retrospective multicentre study included 104 patients with left anterior descending MBs. MB was classified as either superficial or deep, short, or long, whereas all MB vessels were further divided into <50%, 50% to 69%, and ≥70% groups, according to proximal lumen stenosis on invasive coronary angiography. Diagnostic performance and receiver operating characteristics (ROC) of CT-FFR to detect lesion-specific ischemia was assessed on a per-vessel level, using invasive FFR as reference standard. Intraclass correlation coefficient (ICC) and Bland-Altman plots were used for agreement measurement.

RESULTS

Forty-eight MB vessels (46.2%) showed ischemia by invasive FFR (≤0.80). Sensitivity, specificity, and accuracy of CT-FFR to detect functional ischemia were 0.96 (0.85 to 0.99), 0.84 (0.71 to 0.92), and 0.89 (0.81 to 0.94), respectively, in all MB vessels. There were no differences in diagnostic performance between superficial and deep MB or between short and long MB (all P > 0.05). The accuracy of CT-FFR was 0.96 (0.85 to 0.99) in ≥70% stenosis, 0.82 (0.67 to 0.91) in 50% to 69% stenosis, and 0.89 (0.51 to 0.99) in <50% stenosis (P = 0.081). Bland-Altman analysis showed a slight mean difference between CT-FFR and invasive FFR of 0.014 (95% limit of agreement, -0.117 to 0.145). The ICC was 0.775 (95% confidence interval, 0.685-0.842, P < 0.001).

CONCLUSIONS

CT-FFR demonstrated high diagnostic performance for identifying functional ischemia in vessels with MB and concomitant proximal atherosclerotic disease when compared with invasive FFR. However, the clinical use of CT-FFR in patients with MB needs further study for stronger and more robust results.