Background: Atrial cardiomyopathy (ACM) is associated with an increased risk for new-onset atrial fibrillation (AF), progression from paroxysmal to persistent AF-forms and higher arrhythmia recurrence rates after pulmonary vein isolation (PVI). Therefore, the current ESC guidelines on AF recommend to characterize the underlying ACM to better inform and treat patients with AF. Over the past decade, various diagnostic tools were established to diagnose an ACM by analyzing left atrial (LA) structure, and LA electrical and mechanical function.

Aim: To compare head-to-head electroanatomical mapping (EAM) to assess LA low-voltage substrate (LVS), late gadolinium enhancement magnetic resonance imaging (LGE-MRI) to analyse LGE-extent, body surface electrocardiograpghic imaging (ECGI) to measure total atrial conduction time (TACT), digital ECG to analyse amplified p-wave duration (aPWD), and TTE to quantify LA emptying fraction (LA-EF) and LA strain (LAS) regarding ACM diagnosis and outcome prediction after PVI in a homogenous study population.

Methods: Thirty-six ablation-naive patients (65±9 years, 86% male) with persistent AF undergoing PVI were prospectively included. All patients were electrically cardioverted prior to PVI and all analyses were performed in sinus rhythm. LGE-MRI, ECGI using a 252-electrode-array, digital ECG and TTE were conducted one day prior to PVI. Subsequently, a high-density LA voltage map (2124±490 sites) was acquired followed by circumferential PVI. MRI-post-processing-analyses were performed by two independent and blinded expert laboratories (Marrek for the Utah segmentation and Adas3D medical for the image-intensity-ratio(IIR)-method). Analysis of aPWD and LAS during reservoir (LASr), conduit (LAScd) and contraction phase (LASct) were performed automatically. Arrhythmia recurrence was recorded within 12 months following PVI. Relevant ACM was defined as presence of a LA-LVS≥2cm² at 0.5mV, a LGE-extent≥20% using the Utah method, a LA-EF<34%, a LASr<23.5%, a LAScd<13.4%, and a LASct<5.4% as described previously. For the IIR-, ECGI-, and automatically measured aPWD-methods, receiver-operating curve analyses were performed to find the optimal threshold for diagnosis of a relevant ACM as defined in EAM (LA-LVS≥2cm² at 0.5mV) due to a lack of a predefined threshold.    

Results: A LGE-extent of ≥12% using an IIR cut-off of 1.20, a TACT≥148ms and an automatically measured aPWD≥140ms predicted a relevant ACM as defined in EAM with a sensitivity of 76% and a specificity of 60% for LGE IIR 1.20, a sensitivity of 95% and a specificity of 93% for TACT, and a sensitivity of 86% and a specificity of 80% for aPWD, respectively. 
Arrhythmia recurrence in the entire cohort was significantly higher in patients with a LA-LVS≥2cm² at 0.5mV (57% versus 20%, p=0.012), a LGE-extent≥12% at 1.20 IIR (59% versus 14%, p=0.026), a TACT≥148ms (57% versus 20%, p=0.027), an aPWD≥140ms (57% versus 20%, p=0.035), a LA-EF<34% (61% versus 22%, p=0.014) and a LASct<5.4% (64% versus 26%, p=0.014).

Conclusion: ACM can be diagnosed using EAM, LGE-MRI, ECGI, ECG and TTE and is associated with an increased arrhythmia recurrence rate after PVI. However, only measurement of aPWD in digital ECG, and LA-EF and LAS in TTE are easy, cost-effective, non-invasive methods without any risk for complications.