Left Atrial Myopathy and Atrial Arrhythmia Recurrence After Pulmonary Vein Isolation in Patients With Minimal Left Atrial Low Voltage Areas.

BACKGROUND

Atrial low voltage areas (LVAs) provide the substrate for atrial fibrillation (AF). In AF patients with minimal left atrial (LA) LVAs, this substrate has not been well characterised. We determined whether LA myopathy is present in AF patients with minimal LA LVAs (mLVA) by evaluating LA mechanical function and blood biomarkers of structural remodelling.

METHODS

AF patients undergoing pulmonary vein isolation (PVI) and control subjects without AF were prospectively enrolled. In AF patients, mLVA was defined by LA LVA cut points < 1% to < 5% (< 0.5 mV), and the remaining patients at each cut point were +LVA. LA systolic function was evaluated according to dP/dt of LA pressure. LA diastolic function was assessed according to LA wall compliance. Blood biomarkers were assayed with the use of immunosorbent techniques. Atrial arrhythmia (AA) recurrence was assessed 12 months after PVI.

RESULTS

Among 36 control subjects and 60 AF patients, LA dP/dt was lower in mLVA than in control subjects (P < 0.001). +LVA and mLVA had similar dP/dt. LA compliance was lower in mLVA compared with control subjects (P < 0.001), and lower in +LVA vs mLVA (P < 0.05). Patient groups were associated with mechanical function after adjusting for LVA risk factors. N-terminal pro-atrial natriuretic peptide (NT-proANP) was abnormally elevated in 32% of mLVA patients, and the levels were higher in +LVA than mLVA (P < 0.001). mLVA patients with AA recurrence had lower LA dP/dt than those without AA recurrence (P = 0.012).

CONCLUSIONS

mLVA patients have LA mechanical dysfunction and abnormal NT-proANP levels, which are not present in control subjects. AA recurrence in mLVA is associated with LA systolic dysfunction. These findings support the presence of early, diffuse LA myopathy in mLVA.