Myocardial extracellular volume expansion and the risk of recurrent atrial fibrillation after pulmonary vein isolation.

This study tested whether myocardial extracellular volume (ECV) is increased in patients with hypertension and atrial fibrillation (AF) undergoing pulmonary vein isolation and whether there is an association between ECV and post-procedural recurrence of AF. Hypertension is associated with myocardial fibrosis, an increase in ECV, and AF. Data linking these findings are limited. T1 measurements pre-contrast and post-contrast in a cardiac magnetic resonance (CMR) study provide a method for quantification of ECV. Consecutive patients with hypertension and recurrent AF referred for pulmonary vein isolation underwent a contrast CMR study with measurement of ECV and were followed up prospectively for a median of 18 months. The endpoint of interest was late recurrence of AF. Patients had elevated left ventricular (LV) volumes, LV mass, left atrial volumes, and increased ECV (patients with AF, 0.34 ± 0.03; healthy control patients, 0.29 ± 0.03; p < 0.001). There were positive associations between ECV and left atrial volume (r = 0.46, p < 0.01) and LV mass and a negative association between ECV and diastolic function (early mitral annular relaxation [E'], r = -0.55, p < 0.001). In the best overall multivariable model, ECV was the strongest predictor of the primary outcome of recurrent AF (hazard ratio: 1.29; 95% confidence interval: 1.15 to 1.44; p < 0.0001) and the secondary composite outcome of recurrent AF, heart failure admission, and death (hazard ratio: 1.35; 95% confidence interval: 1.21 to 1.51; p < 0.0001). Each 10% increase in ECV was associated with a 29% increased risk of recurrent AF. In patients with AF and hypertension, expansion of ECV is associated with diastolic function and left atrial remodeling and is a strong independent predictor of recurrent AF post-pulmonary vein isolation.

Neilan TG ，Mongeon FP ，Shah RV ，Coelho-Filho O ，Abbasi SA ，Dodson JA ，McMullan CJ ，Heydari B ，Michaud GF ，John RM ，Blankstein R ，Jerosch-Herold M ，Kwong RY ... -  《-》

The association of baseline left atrial structure and function measured with cardiac magnetic resonance and pulmonary vein isolation outcome in patients with drug-refractory atrial fibrillation.

Prognostic significance of left atrial (LA) function in patients with atrial fibrillation (AF) is poorly defined. To examine the association of LA function measured with cardiac magnetic resonance (CMR) feature-tracking and AF recurrence following catheter ablation. One hundred and twenty-one AF patients (72% paroxysmal, mean age 59 ± 10 years) were enrolled. Baseline LA function was measured by calculating passive, active, and total emptying fractions (LAEF) and analysis of global longitudinal strain and strain rates. Patients were followed up for recurrence of AF or atrial tachycardia (AT). Hazard ratios for recurrence were calculated using Cox proportional models adjusted for potential clinical confounders, type of AF, left ventricular ejection fraction, AF duration, LA volume, and late gadolinium enhancement (LGE). During a mean follow-up of 18 ± 9 months, 52 patients (43%) experienced recurrent AF/AT. Patients with recurrent AF/AT had higher baseline LA volume index and lower LA passive, and total LAEF (P < .05 for all). The baseline peak LA strain and strain rates in all phases of LA function were lower in the AF/AT recurrence group (P < .01 for all). In multivariable analysis total LAEF, peak LA strain, and systolic and late diastolic strain rates were associated with recurrence. Both peak LA strain and total LAEF improved prediction of recurrent AT/AF compared to the baseline clinical model, including LA LGE (C statistic 0.82 vs 0.77, P < .05 for both total LAEF and peak LA strain). LA reservoir function was independently associated with recurrent AF/AT after PVI and can additionally improve risk stratification in patients undergoing PVI.

Habibi M ，Lima JAC ，Gucuk Ipek E ，Zimmerman SL ，Zipunnikov V ，Spragg D ，Ashikaga H ，Rickard J ，Marine JE ，Berger RD ，Calkins H ，Nazarian S ... -  《-》

Left ventricular native T1 time and the risk of atrial fibrillation recurrence after pulmonary vein isolation in patients with paroxysmal atrial fibrillation.

Native T1 mapping has emerged as a noninvasive non-contrast magnetic resonance imaging (MRI) method to assess for diffuse myocardial fibrosis. However, LV native T1 time in AF patients and its clinical relevance are unclear. Fifty paroxysmal AF patients referred for PVI (60 ± 8 years, 37 male) and 11 healthy control subjects (57 ± 8 years, 10 male) were studied. All patients were in sinus rhythm during the MRI scan. Native T1 mapping images were acquired using a Modified Look-Locker imaging (MOLLI) sequence in 3 short-axis planes (basal, mid and apical slices) using an electrocardiogram triggered single-shot acquisition with a balanced steady-state free precession readout. Late gadolinium enhanced (LGE) MRI was acquired to evaluate for LV myocardial scar. LV ejection fraction was similar between groups (AF: 61 ± 6%; controls: 60 ± 6%, p=0.75). No LV myocardial scar was observed in any patient on LGE. Myocardial native T1 time was greater in AF patients (1099 ± 52 vs 1042 ± 20 msec, p<0.001). During a median follow-up period of 326 days, 18 of 50 (36%) patients experienced recurrence of AF. Multivariate Cox proportional hazard analysis identified elevated native T1 time as an independent predictor of recurrence of AF (HR: 6.53, 95% CI: 1.25-34.3, p=0.026). There are differences in the native LV myocardial T1 time between AF patients with preserved LV function referred for PVI and normal controls. Native T1 time is an independent predictor of recurrence of AF after PVI in patients with paroxysmal AF.

Kato S ，Foppa M ，Roujol S ，Basha T ，Berg S ，Kissinger KV ，Goddu B ，Manning WJ ，Nezafat R ... -  《-》

Sinus rhythm restores ventricular function in patients with cardiomyopathy and no late gadolinium enhancement on cardiac magnetic resonance imaging who undergo catheter ablation for atrial fibrillation.

Atrial fibrillation (AF) and systolic heart failure (HF) frequently coexist. Restoration of sinus rhythm by catheter ablation may result in a variable improvement in left ventricular (LV) function. Late-gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging identifies irreversible structural change and may predict incomplete recovery of LV function. To prospectively select patients with AF and symptomatic HF but without LV LGE and report the impact of AF ablation on LV function. Patients with AF and symptomatic HF (LV ejection fraction <50%) resistant to at least 1 antiarrhythmic drug and prior electrical cardioversion underwent contrast-enhanced CMR. LGE-negative patients underwent pulmonary vein isolation and left atrial roof line with continued antiarrhythmic medications until follow-up CMR 6 months postablation. Sixteen patients (aged 52 ± 11 years; mean AF duration 37 ± 39 months; left atrial size 44 ± 13 mL/m(2)) underwent AF ablation. At 6 months, 15 of the 16 patients maintained sinus rhythm and underwent CMR. LV ejection fraction increased from 40% ± 10% at baseline to 60% ± 6% (P < .001) and LV end-systolic volume index decreased from 52 ± 12 to 36 ± 9 mL/m(2) (P < .001). Left atrial size decreased from 44 ± 13 to 36 ± 11 mL/m(2) (P < .01). In patients with AF and LV dysfunction in the absence of LGE on CMR, ventricular function normalizes following the restoration of sinus rhythm. CMR may assist in the selection of patients with combined AF and systolic HF most likely to benefit from catheter ablation.

Ling LH ，Taylor AJ ，Ellims AH ，Iles LM ，McLellan AJ ，Lee G ，Kumar S ，Lee G ，Teh A ，Medi C ，Kaye DM ，Kalman JM ，Kistler PM ... -  《-》

Cardiac magnetic resonance T1 mapping of left atrial myocardium.

Cardiac magnetic resonance (CMR) T1 mapping is an emerging tool for objective quantification of myocardial fibrosis. To (a) establish the feasibility of left atrial (LA) T1 measurements, (b) determine the range of LA T1 values in patients with atrial fibrillation (AF) vs healthy volunteers, and (c) validate T1 mapping vs LA intracardiac electrogram voltage amplitude measures. CMR imaging at 1.5 T was performed in 51 consecutive patients before AF ablation and in 16 healthy volunteers. T1 measurements were obtained from the posterior LA myocardium by using the modified Look-Locker inversion-recovery sequence. Given the established association of reduced electrogram amplitude with fibrosis, intracardiac point-by-point bipolar LA voltage measures were recorded for the validation of T1 measurements. The median LA T1 relaxation time was shorter in patients with AF (387 [interquartile range 364-428] ms) compared to healthy volunteers (459 [interquartile range 418-532] ms; P < .001) and was shorter in patients with AF with prior ablation compared to patients without prior ablation (P = .035). In a generalized estimating equations model, adjusting for data clusters per participant, age, rhythm during CMR, prior ablation, AF type, hypertension, and diabetes, each 100-ms increase in T1 relaxation time was associated with 0.1 mV increase in intracardiac bipolar LA voltage (P = .025). Measurement of the LA myocardium T1 relaxation time is feasible and strongly associated with invasive voltage measures. This methodology may improve the quantification of fibrotic changes in thin-walled myocardial tissues.

Beinart R ，Khurram IM ，Liu S ，Yarmohammadi H ，Halperin HR ，Bluemke DA ，Gai N ，van der Geest RJ ，Lima JA ，Calkins H ，Zimmerman SL ，Nazarian S ... -  《-》