Background:

Left atrial cardiomyopathy (LACMP) is considered a precursor or prerequisite of incident atrial fibrillation (AF). Various definitions including humoral, ECG- and echocardiographic parameters have been proposed, but not been rigorously and comparatively investigated and the role of excessive supraventricular ectopic activity (ESVEA) is poorly studied. We aimed to analyse the ten-year risk to develop AF in patients with cardiovascular risk factors and to define the impact of LACMP, its components and ESVEA on AF risk.

Methods and results:

This substudy of the Diast-CHF trial includes 148 patients wihout AF in medical history or baseline Holter ECG. We compared left atrial enlargement (defined as left atrial volume index (LAVI) >35 ml/m²), ESVEA (defined as either > 720 premature atrial contractions (PAC) per day or at least one atrial run > 20 beats per day), P-terminal force in lead V₁ (PTFV₁ - continuous and categorical) and NT-terminal pro brain natriuretic peptide (NT-proBNP) > 250 pg/ml. LACMP was defined as either left atrial enlargement, ESVEA or elevated NT-proBNP. Baseline examination included medical history, physical examination, echocardiography, 12-lead-ECG and 7-day-Holter ECG. Fifty-three patients fulfilled at least one criterion of LACMP while three patients fulfilled all criteria.

After ten years of follow-up, AF was newly detected in nine patients (17 %) with LACMP and five patients (5 %) without LACMP (p=0.036). LAVI (p=0.005), ESVEA (p=0.016) and NT-proBNP (p=0.010) as well as all parameters combined (p=0.007) showed significant impact on AF-free survival in univariate analysis while PTFV₁ did not. In a combined Cox model of LACMP parameters, significant associations were found for log-transformed NT-proBNP (hazard ratio [HR] 3.23; 95% confidence interval [CI] 1.06-9.78) and log-transformed PAC (HR, 2.56; 95% CI, 1.26-5.18), but not LAVI (HR, 1.02; 95% CI 0.97-1.08).

Figure 1: Kaplan-Meier-curve of AF-free survival in patients with and without LACMP

Conclusion:

The risk for AF is higher in patients with evidence of left atrial cardiomyopathy. NT-proBNP and premature atrial contractions independently predict AF-free survival. The role of supraventricular ectopic activity is underestimated and requires further study.

Key words:

Atrial fibrillation, heart failure, left atrial cardiomyopathy, stroke, biological markers