Benedict T Costello1, Aleksandr Voskoboinik2, Abdul M Qadri3, Murray Rudman3, Mark C Thompson3, Ferris Touma4, Andre La Gerche5, James L Hare6, Stavroula Papapostolou6, Jonathan M Kalman7, Peter M Kistler8, Andrew J Taylor9. 1. Baker Heart & Diabetes Institute, Melbourne, Australia; Heart Centre, The Alfred Hospital, Melbourne, Australia; Department of Cardiology, St Vincent's Hospital, Australia. 2. Baker Heart & Diabetes Institute, Melbourne, Australia; Heart Centre, The Alfred Hospital, Melbourne, Australia; Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia. 3. Department of Mechanical and Aerospace Engineering, Monash University, Australia. 4. Heart Centre, The Alfred Hospital, Melbourne, Australia. 5. Baker Heart & Diabetes Institute, Melbourne, Australia; Department of Cardiology, St Vincent's Hospital, Australia. 6. Baker Heart & Diabetes Institute, Melbourne, Australia; Heart Centre, The Alfred Hospital, Melbourne, Australia. 7. Department of Cardiology, Royal Melbourne Hospital, Melbourne, Australia; Department of Medicine, University of Melbourne, Australia. 8. Baker Heart & Diabetes Institute, Melbourne, Australia; Heart Centre, The Alfred Hospital, Melbourne, Australia; Department of Medicine, University of Melbourne, Australia. 9. Baker Heart & Diabetes Institute, Melbourne, Australia; Heart Centre, The Alfred Hospital, Melbourne, Australia; Faculty of Medicine, Nursing and Health Sciences, Monash University. Electronic address: a.taylor@alfred.org.au.
Abstract
BACKGROUND: Paroxysmal atrial fibrillation (PAF) is associated with cardioembolic risk, however events may occur during sinus rhythm (SR). 4D-flow cardiac magnetic resonance (CMR) imaging allows visualisation of left atrial blood flow, to determine the residence time distribution (RTD), an assessment of atrial transit time. OBJECTIVE: To determine if atrial transit time is prolonged in PAF patients during SR, consistent with underlying atrial stasis. METHOD: 91 participants with PAF and 18 healthy volunteers underwent 4D flow analysis in SR. Velocity fields were produced RTDs, calculated by seeding virtual 'particles' at the right upper pulmonary vein and counting them exiting the mitral valve. An exponential decay curve quantified residence time of particles in the left atrium, and atrial stasis was expressed as the derived constant (RTDTC) based on heartbeats. The RTDTC was evaluated within the PAF group, and compared to healthy volunteers. RESULTS: Patients with PAF (n = 91) had higher RTDTC compared with gender-matched controls (n = 18) consistent with greater atrial stasis (1.68 ± 0.46 beats vs 1.51 ± 0.20 beats; p = .005). PAF patients with greater thromboembolic risk had greater atrial stasis (median RTDTC of 1.72 beats in CHA₂DS₂-VASc≥2 vs 1.52 beats in CHA₂DS₂-VASc<2; p = .03), only female gender and left ventricular ejection fraction contributed significantly to the atrial RTDTC (p = .006 and p = .023 respectively). CONCLUSIONS: Atrial stasis quantified by 4D flow is greater in PAF, correlating with higher CHA₂DS₂-VASc scores. Female gender and systolic dysfunction are associated with atrial stasis. RTD offers an insight into atrial flow that may be developed to provide a personalised assessment of thromboembolic risk.
BACKGROUND:Paroxysmal atrial fibrillation (PAF) is associated with cardioembolic risk, however events may occur during sinus rhythm (SR). 4D-flow cardiac magnetic resonance (CMR) imaging allows visualisation of left atrial blood flow, to determine the residence time distribution (RTD), an assessment of atrial transit time. OBJECTIVE: To determine if atrial transit time is prolonged in PAF patients during SR, consistent with underlying atrial stasis. METHOD: 91 participants with PAF and 18 healthy volunteers underwent 4D flow analysis in SR. Velocity fields were produced RTDs, calculated by seeding virtual 'particles' at the right upper pulmonary vein and counting them exiting the mitral valve. An exponential decay curve quantified residence time of particles in the left atrium, and atrial stasis was expressed as the derived constant (RTDTC) based on heartbeats. The RTDTC was evaluated within the PAF group, and compared to healthy volunteers. RESULTS:Patients with PAF (n = 91) had higher RTDTC compared with gender-matched controls (n = 18) consistent with greater atrial stasis (1.68 ± 0.46 beats vs 1.51 ± 0.20 beats; p = .005). PAF patients with greater thromboembolic risk had greater atrial stasis (median RTDTC of 1.72 beats in CHA₂DS₂-VASc≥2 vs 1.52 beats in CHA₂DS₂-VASc<2; p = .03), only female gender and left ventricular ejection fraction contributed significantly to the atrial RTDTC (p = .006 and p = .023 respectively). CONCLUSIONS:Atrial stasis quantified by 4D flow is greater in PAF, correlating with higher CHA₂DS₂-VASc scores. Female gender and systolic dysfunction are associated with atrial stasis. RTD offers an insight into atrial flow that may be developed to provide a personalised assessment of thromboembolic risk.
Authors: Mark T Mills; Ciaran Grafton-Clarke; Gareth Williams; Rebecca C Gosling; Abdulaziz Al Baraikan; Andreas L Kyriacou; Paul D Morris; Julian P Gunn; Peter P Swoboda; Eylem Levelt; Vasiliki Tsampasian; Rob J van der Geest; Andrew J Swift; John P Greenwood; Sven Plein; Vass Vassiliou; Pankaj Garg Journal: Wellcome Open Res Date: 2021-05-18