Atrial Fibrosis, Ischaemic Stroke and Atrial Fibrillation

Atrial fibrosis is an important component of the arrhythmic substrate in AF. Evidence suggests that atrial fibrosis also plays a role in increasing the risk of stroke in patients with the arrhythmia. Patients with embolic stroke of undetermined source (ESUS), who are suspected to have AF but are rarely shown to have it, frequently demonstrate evidence of atrial fibrosis; measured using late-gadolinium enhancement MRI, this manifests as atrial remodelling encompassing structural, functional and electrical properties. In this review, the authors discuss the available evidence linking atrial disease, including fibrosis, with the risk of ischaemic stroke in AF, as well as in the ESUS population, in whom it has been linked to recurrent stroke and new-onset AF. They also discuss the implications of this association on future research that may elucidate the mechanism of stroke and stroke prevention strategies in the AF and ESUS populations

Association of atrial tissue fibrosis identified by delayed enhancement MRI and atrial fibrillation catheter ablation: the DECAAF study

IMPORTANCE: Left atrial fibrosis is prominent in patients with atrial fibrillation (AF). Extensive atrial tissue fibrosis identified by delayed enhancement magnetic resonance imaging (MRI) has been associated with poor outcomes of AF catheter ablation. OBJECTIVE: To characterize the feasibility of atrial tissue fibrosis estimation by delayed enhancement MRI and its association with subsequent AF ablation outcome. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, prospective, observational cohort study of patients diagnosed with paroxysmal and persistent AF (undergoing their first catheter ablation) conducted between August 2010 and August 2011 at 15 centers in the United States, Europe, and Australia. Delayed enhancement MRI images were obtained up to 30 days before ablation. MAIN OUTCOMES AND MEASURES: Fibrosis quantification was performed at a core laboratory blinded to the participating center, ablation approach, and procedure outcome. Fibrosis blinded to the treating physicians was categorized as stage 1 (<10% of the atrial wall), 2 (≥10%-<20%), 3 (≥20%-<30%), and 4 (≥30%). Patients were followed up for recurrent arrhythmia per current guidelines using electrocardiography or ambulatory monitor recording and results were analyzed at a core laboratory. Cumulative incidence of recurrence was estimated by stage at days 325 and 475 after a 90-day blanking period (standard time allowed for arrhythmias related to ablation-induced inflammation to subside) and the risk of recurrence was estimated (adjusting for 10 demographic and clinical covariates). RESULTS: Atrial tissue fibrosis estimation by delayed enhancement MRI was successfully quantified in 272 of 329 enrolled patients (57 patients [17%] were excluded due to poor MRI quality). There were 260 patients who were followed up after the blanking period (mean [SD] age of 59.1 [10.7] years, 31.5% female, 64.6% with paroxysmal AF). For recurrent arrhythmia, the unadjusted overall hazard ratio per 1% increase in left atrial fibrosis was 1.06 (95% CI, 1.03-1.08; P < .001). Estimated unadjusted cumulative incidence of recurrent arrhythmia by day 325 for stage 1 fibrosis was 15.3% (95% CI, 7.6%-29.6%); stage 2, 32.6% (95% CI, 24.3%-42.9%); stage 3, 45.9% (95% CI, 35.5%-57.5%); and stage 4, 51.1% (95% CI, 32.8%-72.2%) and by day 475 was 15.3% (95% CI, 7.6%-29.6%), 35.8% (95% CI, 26.2%-47.6%), 45.9% (95% CI, 35.6%-57.5%), and 69.4% (95% CI, 48.6%-87.7%), respectively. Similar results were obtained after covariate adjustment. The addition of fibrosis to a recurrence prediction model that includes traditional clinical covariates resulted in an improved predictive accuracy with the C statistic increasing from 0.65 to 0.69 (risk difference of 0.05; 95% CI, 0.01-0.09). CONCLUSIONS AND RELEVANCE: Among patients with AF undergoing catheter ablation, atrial tissue fibrosis estimated by delayed enhancement MRI was independently associated with likelihood of recurrent arrhythmia. The clinical implications of this association warrant further investigation

Razlike u fibrozi atrija po dobi i spolu među pacijentima s atrijskom fibrilacijom

Aim: Age and female sex are associated with a higher risk of stroke in atrial fibrillation (AF). We sought to determine whether advancing age and female sex are associated with higher atrial fibrosis. Methods and results: We conducted an observational cohort study of patients with AF enrolled in the University of Utah AF Database and a non-AF control group who underwent lategadolinium enhancement magnetic resonance imaging (LGE-MRI) for atrial fibrosis quantification. Participants with contraindications for contrast MRI scanning were excluded. Nine hundred and eight consecutive men and women with AF and 15 non-AF controls were included in this study. Left atrial fibrosis increased with age in both men and women with AF. Women with AF (n = 316) were older than men (n = 592): mean age 68.7±11.6 vs. 64.9±11.7 years; P < 0.01, and had higher left atrial fibrosis compared with men 17.5 ± 10.1% vs. 15.3 ± 8.9%; P < 0.001. Women also had a higher prevalence of prior stroke than men (15.8% vs. 6.5%; P < 0.001). Age and sex relationships with atrial fibrosis remained significant in multivariate analysis. Compared with the non-AF control group, patients with AF they had significantly higher atrial fibrosis: 16.0 ± 9.4 vs. 5.5 ± 5.8%; P < 0.001. Conclusions: Advancing age and female sex are associated with a higher burden of atrial fibrosis in patients with AF. Women with a prior history of stroke also have higher fibrosis than women and men without a history of stroke. Advanced fibrosis may explain the female and age association with stroke in AF.Cilj: Dob i ženski spol povezani su s većim rizikom za moždani udar u osoba s atrijskom fibrilacijom (AF). Željeli smo utvrditi jesu li starija životna dob i ženski spol povezani s višom razinom fibroze atrija. Metode i rezultati: Proveli smo kohortnu studiju u koju smo uključili pacijente s AF koji su bili upisani u bazu podataka na Sveučilištu Utah i kontrolnu skupinu bez AF, koja je podvrgnuta magnetskoj rezonanciji s kasnim gadolinijskim kontrastnim pojačanjem prikaza (engl. late-gadolinium enhancement magnetic resonance imaging, LGE-MRI) radi određivanja atrijske fibroze. Osobe s kontraindikacijama za LGE-MRI pretragu su bile isključene. Devet stotina i osam uzastopnih ispitanika muškog i ženskog spola s AF i 15 kontrola bez AF-a bilo je uključeno u ovo istraživanje. Fibroza lijevog atrija se povećavala s dobi i kod muškaraca i kod žena s AF. Žene s AF (n=316) bile su starije od muškaraca (n=592), s prosječnom dobi od 68,7 godina ± 11,6 u odnosu na 64,9 ± 11,7 godina u muškaraca (P<0,001) te su imale višu razinu fibroze lijevog atrija u usporedbi s muškarcima (17,5 ± 10,1% nasuprot 15,3 ± 8,9%; P<0,001). Žene su također imale veću prevalenciju prethodnog moždanog udara u usporedbi s muškarcima (15,8% nasuprot 6,5%; P<0,001). Dob i spol bili su prediktori atrijske fibroze u multivarijatnoj analizi. U usporedbi s kontrolnom skupinom koja nema AF, pacijenti s AF imali su značajno višu razinu atrijske fibroze (16,0 ± 9,4 naspram 5,5 ± 5,8%; P<0,001). Zaključci: Starija životna dob i ženski spol povezani su s većim teretom atrijske fibroze kod pacijenata s AF. Žene koje imaju prethodni moždani udar također imaju i veću razinu atrijske fibroze u usporedbi sa ženama i muškarcima koji nisu imali moždani udar. Uznapredovala fibroza može objasniti povezanost između ženskog spola i starije životne dobi s moždanim udarom kod AF