Right atrium and cryptogenic ischaemic stroke in the young: a case-control study

Abstract

Background: Recent studies suggest left atrial (LA) dysfunction in cryptogenic stroke. We studied the dynamics of right atrium (RA) and right atrial appendage (RAA) in young adults with cryptogenic stroke. We hypothesised that bi-atrial dysfunction and blood stagnation might contribute to thrombosis formation in patients with patent foramen ovale (PFO), as deep venous thrombosis is detected only in the minority of patients.

Methods: Thirty patients (aged 18-49) with a first-ever cryptogenic stroke and 30 age-matched and sex-matched stroke-free controls underwent cardiac magnetic resonance (CMR) imaging. An approach to estimate the RAA volume was developed, using crista terminalis and pectinate muscles as anatomical landmarks. Atrial expansion indices were calculated as (maximal volume - minimal volume) ×100%/minimal volume. Total pulmonary to systemic blood flow ratio (Qp/Qs) was based on phase contrast CMR. Right-to-left shunt (RLS) was evaluated with transoesophageal echocardiography in 29 patients and transcranial Doppler in 30 controls, moderate-to-severe RLS considered as clinically significant.

Results: We found that RA and RAA volumes were similar between patients and controls. Also, RA expansion index was similar, but RAA (95.6%±21.6% vs 108.7%±25.8%, p=0.026) and LA (126.2%±28% vs 144.9%±36.3%, p=0.023) expansion indices were lower in patients compared with controls. Seven (24%) of 29 patients had an RLS compared with 1 (3%) of 30 controls (p=0.012). Among 59 study subjects, RLS was associated with lower RA (81.9%±15.9% vs 98.5%±29.5%, p=0.030), RAA (84.7%±18% vs 105.6%±24.1%, p=0.022), LA (109.8%±18.6% vs 140.1%±33.7%, p=0.017) and LAA (median 102.9% (IQR 65.6%-121.7%) vs 229.1% (151.8%-337.5%], p=0.002) expansion indices and lower Qp/Qs ratio (0.91±0.06 vs 0.98±0.07, p=0.027).

Conclusions: This study suggests bi-atrial dysfunction in young adults with cryptogenic stroke, associated with moderate-to-severe RLS. Dysfunction of the atria and atrial appendages may be an additional mechanism for PFO-related stroke.

Trial registration number: NCT01934725.

Keywords: echocardiography; magnetic resonance imaging; stroke.

Conflict of interest statement

Competing interests: JPi reports personal fees from General Electric Healthcare, outside the submitted work. JPu reports personal fees from Boehringer Ingelheim, Bayer, Portola and Terve Media, research grants and personal fees from BMS-Pfizer and Abbott/St Jude Medical, research grants from Business Finland and Amgen, research collaboration with Nokia Technologies, Bittium and BcB Medical, research collaboration and stock ownership with Vital Signum, outside the submitted work; and he has participated in the European Stroke Organisation’s guideline working groups on (1) Post-stroke hyperglycaemia and (2) Secondary prevention in patients with atrial fibrillation, and in the Finnish Duodecim Society’s guideline working group on ischaemic stroke and transient ischaemic attack. Other authors have nothing to disclose.

© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

Figures

Figure 1

Delineation of right atrium (RA) and right atrial appendage (RAA) at minimum (ventricular end-diastole) (A) and maximum (ventricular end-systole) (B). RAA was defined as the whole anterolateral triangular part of the RA characterised by endocardial pectinate muscles and demarcated by crista terminalis distinguishing it from smooth-walled venous endocardial surface. A patient with cryptogenic ischaemic stroke with minimal and maximal RA volumes of 56 mL and 112 mL, RAA volumes of 18 mL and 40 mL and RA and RAA expansion indices of 100% and 123%.

Figure 2

A lateral view of right atrial body (green), right atrial appendage (RAA) (red) and right ventricle (yellow) at ventricular end-diastole (minimum atrial volume) (A) and ventricular end-systole (maximal atrial volume) (B). Posterosuperior view of right atrial body (green), RAA (red) and right ventricle (light green) in corresponding cardiac phases (C, D). The same patient as in figure 1.

Figure 3

Right atrial appendage (RAA) (A) and left atrial (LA) (B) expansion indices in patients versus controls.

Figure 4

Comparison of right atrial (RA), right atrial appendage (RAA), left atrial (LA) and left atrial appendage (LAA) expansion indices in all study subjects, based on right-to-left shunt.