Objectives: Investigation of which atrial pacing modality provides atrial synchrony and the most physiological atrial contraction pattern in patients with brady-tachycardia syndrome.
Methods: Fifteen healthy subjects and 57 patients with sinus node dysfunction, atrial fibrillation recurrences, and prolonged P-wave on the electrocardiogram treated with multisite atrial (MSA) pacing were studied. One atrial lead was implanted in the coronary sinus (CS) ostium area, the other at the right atrial appendage (RAA): RAA+CS group (28 patients), or Bachmann's bundle (BB) region: BB+CS group (29). Sinus rhythm (SR) and CS, RAA, BB, RAA+CS, and BB+CS pacing modalities were evaluated. Electromechanical delay (EMD) in atrial walls was assessed by tissue Doppler echocardiography. Interatrial (DeltainterA), intra-right (DeltaRA), and intra-left (DeltaLA) atrial dyssynchrony were calculated.
Results: During SR, in the study group versus controls, important DeltainterA: 55 +/- 23 versus 22 +/- 11 ms (P < 0.01) and DeltaLA: 47 +/- 21 versus 21 +/- 6 ms (P < 0.001) were present. Single-site BB and both MSA pacing modes restored DeltainterA and DeltaLA (DeltainterA: 24 +/- 16, 20 +/- 13 and 14 +/- 9 ms, DeltaLA: 28 +/- 18, 28 +/- 13 and 20 +/- 10 ms during BB, RAA+CS and BB+CS pacing, respectively). CS pacing prolonged lateral RA EMD, while RAA pacing LA walls EMD, which resulted in DeltainterA persistence. CS pacing induced DeltaRA (50 +/- 23 vs 16 +/- 8 ms, P < 0.0001 vs controls). Atrial contraction sequence during BB pacing resembled that observed in controls.
Conclusions: (1) Single-site BB and both MSA pacing modes restored atrial synchrony. (2) Single-site RAA and CS ostium pacing retained interatrial dyssynchrony; moreover, CS pacing created RA dyssynchrony. (3) Single-site BB pacing provided physiological atrial contraction sequence.