January 1, 2019Open Access

Validation of aortic valve 4D flow analysis and myocardial deformation by cardiovascular magnetic resonance in patients after the arterial switch operation

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Transposition of the great arteries after arterial switch operation (n=81). Intervention: 4D flow cardiovascular magnetic resonance and feature tracking vs. 2D flow CMR and echocardiographic speckle tracking. Primary outcome: Agreement between 4D flow and 2D flow assessment for degree of aortic regurgitation (ICC 0.85).

Q: What does this research mean for the field?

Aortic 4D flow and CMR feature tracking demonstrate good to excellent agreement with 2D flow assessment and echocardiographic speckle tracking for evaluating aortic valve competence and left ventricular deformation in patients after the arterial switch operation. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

Aortic 4D flow and CMR feature tracking demonstrated good to excellent agreement with 2D flow assessment (ICC 0.85) and echocardiographic speckle tracking (ICC 0.80) for evaluating aortic valve competence and left ventricular deformation in patients after the arterial switch operation.

Study Design

Type

Cross-Sectional (n=81)

Multicenter

PICO

Population

81 patients older than 12 years (median age 20.6, 27% female) who underwent the arterial switch operation for transposition of the great arteries, evaluated cross-sectionally with CMR and echocardiography.

Exposure / Comparator

4D flow cardiovascular magnetic resonance and feature tracking vs 2D flow CMR and echocardiographic speckle tracking

Primary Outcome

Agreement between 4D flow and 2D flow assessment for degree of aortic regurgitation — ICC 0.85

Main Result

Effect estimate: ICC 0.85

Limitations

2D flow CMR data was acquired at 20 frames/cycle, while 4D and cine images were acquired at 30 frames/cycle, potentially resulting in lower peak velocity and stroke volumes.
2D flow was acquired on breath hold, whereas 4D flow was performed with free breathing.
No golden standard was readily available for flow measurements or feature tracking.
Feature tracking on 2D cine images has lower temporal resolution than echocardiography, and through-plane motion may cause inadequate tracking.

Abstract

BACKGROUND: Aortic regurgitation (AR) and subclinical left ventricular (LV) dysfunction expressed by myocardial deformation imaging are common in patients with transposition of the great arteries after the arterial switch operation (ASO). Echocardiographic evaluation is often hampered by reduced acoustic window settings. Cardiovascular magnetic resonance (CMR) imaging provides a robust alternative as it allows for comprehensive assessment of degree of AR and LV function. The purpose of this study is to validate CMR based 4-dimensional flow quantification (4D flow) for degree of AR and feature tracking strain measurements for LV deformation assessment in ASO patients. METHODS: A total of 81 ASO patients (median 20.6 years, IQR 13.5-28.4) underwent CMR for 4D and 2D flow analysis. CMR global longitudinal strain (GLS) feature tracking was compared to echocardiographic (echo) speckle tracking. Agreements between and within tests were expressed as intra-class correlation coefficients (ICC). RESULTS: Eleven ASO patients (13.6%) showed AR > 5% by 4D flow, with good correlation to 2D flow assessment (ICC = 0.85). 4D flow stroke volume of the aortic valve demonstrated good agreement to 2D stroke volume over the mitral valve (internal validation, ICC = 0.85) and multi-slice planimetric LV stroke volume (external validation, ICC = 0.95). 2D flow stroke volume showed slightly less, though still good agreement with 4D flow (ICC = 0.78) and planimetric LV stroke volume (ICC = 0.87). GLS by CMR was normal (- 18.8 ± 4.4%) and demonstrated good agreement with GLS and segmental analysis by echocardiographic speckle tracking (GLS = - 17.3 ± 3.1%, ICC of 0.80). CONCLUSIONS: Aortic 4D flow and CMR feature tracking GLS analysis demonstrate good to excellent agreement with 2D flow assessment and echocardiographic speckle tracking, respectively, and can therefore reliably be used for an integrated and comprehensive CMR analysis of aortic valve competence and LV deformation analysis in ASO patients.

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