Kat-ARC accelerated 4D flow CMR: clinical validation for transvalvular flow and peak velocity assessment

Background: To validate the k-adaptive-t autocalibrating reconstruction for Cartesian sampling (kat-ARC), an exclusive sparse reconstruction technique for four-dimensional (4D) flow cardiac magnetic resonance (CMR) using conservation of mass principle applied to transvalvular flow.   Methods: This observational retrospective study (2020/21-075) was approved by the local ethics committee at the University of East Anglia. Consent was waived. Thirty-five patients who had a clinical CMR scan were included. CMR protocol included cine and 4D flow using Kat-ARC acceleration factor 6. No respiratory navigation was applied. For validation, the agreement between mitral net flow (MNF) and the aortic net flow (ANF) was investigated. Additionally, we checked the agreement between peak aortic valve velocity derived by 4D flow and that derived by continuous-wave Doppler echocardiography in 20 patients.   Results: The median age of our patient population was 63 years (interquartile range [IQR] 54–73), and 18/35 (51%) were male. Seventeen (49%) patients had mitral regurgitation, and seven (20%) patients had aortic regurgitation. Mean acquisition time was 8 ± 4 min. MNF and ANF were comparable: 60 mL (51−78) versus 63 mL (57−77), p = 0.310). There was an association between MNF and ANF (rho = 0.58, p < 0.001). Peak aortic valve velocity by Doppler and 4D flow were comparable (1.40 m/s, [1.30−1.75] versus 1.46 m/s [1.25−2.11], p = 0.602) and also correlated with each other (rho = 0.77, p < 0.001).   Conclusions: Kat-ARC accelerated 4D flow CMR quantified transvalvular flow in accordance with the conservation of mass principle and is primed for clinical translation

Automated 4D flow cardiac MRI pipeline to derive peak mitral inflow diastolic velocities using short-axis cine stack: Two centre validation study against echocardiographic pulse-wave doppler

Background: Measurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities. Methods: Patients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately. Results: Forty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r=0.73, P<0.001) and peak A-wave velocities (r=0.88, P<0.001). Moreover, there was a significant correlation between automated 4D flow CMR and TTE for peak-E wave velocity in sinus rhythm-only patients (r=0.68, P<0.001) and AF-only patients (r=0.81, P=0.014). Excellent intra-and inter-observer variability was demonstrated for both parameters. Conclusion: Automated dynamic peak mitral inflow diastolic velocity tracing using 4D flow CMR is comparable to Doppler echocardiography and has excellent repeatability for clinical use. However, 4D flow CMR can potentially underestimate peak velocity in patients with AF

Paclitaxel drug coated balloon-only angioplasty for de novo coronary artery disease in elective clinical practice

Objective: We aimed to investigate the safety of drug-coated balloon (DCB)-only angioplasty compared to drug-eluting stent (DES), as part of routine clinical practice. Background: The recent BASKETSMALL2 trial demonstrated the safety and efficacy of DCB angioplasty for de novo small vessel disease. Registry data have also demonstrated that DCB angioplasty is safe; however, most of these studies are limited due to long recruitment time and a small number of patients with DCB compared to DES. Therefore, it is unclear if DCB-only strategy is safe to incorporate in routine elective clinical practice. Methods: We compared all-cause mortality and major cardiovascular endpoints (MACE) including unplanned target lesion revascularisation (TLR) of all patients treated with DCB or DES for first presentation of stable angina due to de novo coronary artery disease between 1st January 2015 and 15th November 2019. Data were analysed with Cox regression models and cumulative hazard plots. Results: We present 1237 patients; 544 treated with DCB and 693 treated with DES for de novo, mainly large-vessel coronary artery disease. On multivariable Cox regression analysis, only age and frailty remained significant adverse predictors of all-cause mortality. Univariable, cumulative hazard plots showed no difference between DCB and DES for either all-cause mortality or any of the major cardiovascular endpoints, including unplanned TLR. The results remained unchanged following propensity score matched analysis. Conclusion: DCB-only angioplasty, for stable angina and predominantly large vessels, is safe compared to DES as part of routine clinical practice, in terms of all-cause mortality and MACE including unplanned TLR