High-Speed On-Site Deep Learning-Based FFR-CT Algorithm: Evaluation Using Invasive Angiography as the Reference Standard

BACKGROUND. Estimation of fractional flow reserve from coronary CTA (FFR-CT) is an established method of assessing the hemodynamic significance of coronary lesions. However, clinical implementation has progressed slowly, partly because of off-site data transfer with long turnaround times for results. OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of FFR-CT computed on-site with a high-speed deep learning-based algorithm with invasive hemodynamic indexes as the reference standard. METHODS. This retrospective study included 59 patients (46 men, 13 women; mean age, 66.5 ± 10.2 years) who underwent coronary CTA (including calcium scoring) followed within 90 days by invasive angiography with invasive fractional flow reserve (FFR) and/or instantaneous wave-free ratio measurements from December 2014 to October 2021. Coronary artery lesions were considered to have hemodynamically significant stenosis in the presence of invasive FFR of 0.80 or less and/or instantaneous wave-free ratio of 0.89 or less. A single cardiologist evaluated the CTA images using an on-site deep learning-based semiautomated algorithm entailing a 3D computational flow dynamics model to determine FFR-CT for coronary artery lesions detected with invasive angiography. Time for FFR-CT analysis was recorded. FFR-CT analysis was repeated by the same cardiologist in 26 randomly selected examinations and by a different cardiologist in 45 randomly selected examinations. Diagnostic performance and agreement were assessed. RESULTS. A total of 74 lesions were identified with invasive angiography. FFR-CT and invasive FFR had strong correlation (r = 0.81) and, in Bland-Altman analysis, bias of 0.01 and 95% limits of agreement of -0.13 to 0.15. FFR-CT had AUC for hemodynamically significant stenosis of 0.975. At a cutoff of 0.80 or less, FFR-CT had 95.9% accuracy, 93.5% sensitivity, and 97.7% specificity. In 39 lesions with severe calcifications (≥ 400 Agatston units), FFR-CT had AUC of 0.991 and at a cutoff of 0.80, 94.7% sensitivity, 95.0% specificity, and 94.9% accuracy. Mean analysis time per patient was 7 minutes 54 seconds. Intraobserver agreement (intraclass correlation coefficient, 0.85; bias, -0.01; 95% limits of agreement, -0.12 and 0.10) and interobserver agreement (intraclass correlation coefficient, 0.94; bias, -0.01; 95% limits of agreement, -0.08 and 0.07) were good to excellent. CONCLUSION. A high-speed on-site deep learning-based FFR-CT algorithm had excellent diagnostic performance for hemodynamically significant stenosis with high reproducibility. CLINICAL IMPACT. The algorithm should facilitate implementation of FFR-CT technology into routine clinical practice.

Meta-analysis of intravascular volume expansion strategies to prevent contrast-associated acute kidney injury following invasive angiography

OBJECTIVE

To perform a detailed analysis of published data regarding intravascular volume expansion to prevent contrast-associated acute kidney injury (CA-AKI) and to determine if an ideal dose of IV fluids can be recommended.

BACKGROUND

Administration of contrast media during invasive angiography is associated with CA-AKI. Intravascular volume expansion is the most effective intervention to prevent CA-AKI, yet evidenced based protocols are lacking.

METHODS

Literature review and meta-analysis of randomized controlled trials (RCT) of patients receiving IV volume expansion as prophylaxis for CA-AKI was performed. Normal saline, Lactated Ringer's and sodium bicarbonate were included. The primary outcome was incidence of CA-AKI.

RESULTS

37 RCTs studying 12,166 patients were included. Mean age was 67 ± 5 years, 70% of the patients were male. 68% had chronic kidney disease, 41% diabetes, and 30% heart failure. The incidence of CA-AKI was 9.5% (95% CI: 8-12%). IV expansion versus no volume administration was associated with a lower risk of CA-AKI (RR:0.62; 95% CI: 0.49-0.77, p < .001). Intensive IV volume expansion was associated with a reduced risk of CA-AKI(RR: 0.66; 95%CI: 0.52-0.85, p < .01). The intensive IV volume expansion arm received significantly more fluids than the standard protocols: 1,574(1,123 - 1,913) ml versus 849(558-1,067) ml (p = .03) without significant difference in the duration of infusion (median of 12 vs. 17 hr, p = .1) or pulmonary edema (1.7% vs 1.3%, p = .7).

CONCLUSIONS

Despite high variability in protocols used, IV volume expansion is effective in preventing CA-AKI. Intensive IVF expansion (median 1.6 L over 17 hr) was associated with decreased risk of CA-AKI.

Transradial Approach to Coronary Angiography and Percutaneous Intervention in Patients With Dextrocardia

Patients with dextrocardia present unique challenges in the catheterization laboratory. Variable coronary artery anatomy impacts percutaneous access, catheter selection and manipulation, and image acquisition. This is a review of all published reports of radial artery access for diagnostic and/or therapeutic coronary interventions in patients with dextrocardia. We conclude that the radial approach is safe and effective in these patients and should be used without hesitation. In addition, interventionalists should consider use of multipurpose catheters and possess an understanding of how mirror-image fluoroscopy impacts catheter manipulation. Furthermore, we propose a stepwise approach to arterial access, fluoroscopy, and catheter selection for operator reference while treating dextrocardia patients.

Congenital anomaly of coronary artery: absence of left circumflex artery

The prevalence of congenital coronary artery anomalies is approximately 1% in the general population. They are a common cause of sudden death in younger persons. Congenital absence of the left circumflex artery is usually a benign condition but can cause symptoms of exertional angina. We present a case of a 59-year-old female who presented with complaints of chest pain. She was evaluated by the cardiology service. An invasive angiogram identified the absence of the circumflex artery, a large right coronary artery, and large septal and diagonal branches of the left main coronary artery possibly as a compensatory mechanism to supply blood to the LCx territories. It is important to define coronary anatomy as anomalies dictate which cardiac intervention should be attempted in cases of ischemia.

ACES (Accelerated Chest Pain Evaluation With Stress Imaging) Protocols Eliminate Testing Disparities in Patients With Chest Pain

BACKGROUND

Patients from racial and ethnic minority groups presenting to the Emergency Department (ED) with chest pain experience lower odds of receiving stress testing compared with nonminorities. Studies have demonstrated that care pathways administered within the ED can reduce health disparities, but this has yet to be studied as a strategy to increase stress testing equity.

METHODS

A secondary analysis from 3 randomized clinical trials involving ED patients with acute chest pain was performed to determine whether a care pathway, ACES (Accelerated Chest pain Evaluation with Stress imaging), reduces the racial disparity in index visit cardiac testing between African American (AA) and White patients. Three hundred thirty-four participants with symptoms and findings indicating intermediate to high risk for acute coronary syndrome were enrolled in 3 clinical trials. Major exclusions were ST-segment elevation, initial troponin elevation, and hemodynamic instability. Participants were randomly assigned to receive usual inpatient care, or ACES. The ACES care pathway includes placement in observation for serial cardiac markers, with an expectation for stress imaging. The primary outcome was index visit objective cardiac testing, compared among AA and White participants.

RESULTS

AA participants represented 111/329 (34%) of the study population, 80/220 (36%) of the ACES group and 31/109 (28%) of the usual care group. In usual care, objective testing occurred less frequently among AA (22/31, 71%) than among White (69/78, 88%, P = 0.027) participants, primarily driven by cardiac catheterization (3% vs. 24%; P = 0.012). In ACES, testing rates did not differ by race [AA 78/80 (98%) vs. White 138/140 (99%); P = 0.623]. At 90 days, death, MI, and revascularization did not differ in either group between AA and White participants.

CONCLUSIONS

A care pathway with the expectation for stress imaging eliminates the racial disparity among AA and White participants with chest pain in the acquisition of index-visit cardiovascular testing.