Hemodynamic effects of alternative atrial pacing sites in patients with paroxysmal atrial fibrillation.

Recently, multisite atrial pacing has been suggested as an alternative therapy to prevent recurrences of paroxysmal atrial fibrillation (PAF). A study was conducted to compare the acute effects of biatrial (BiA), left atrial (LA), and right atrial appendage (RAA) pacing on cardiac hemodynamics. In 14 patients with PAF and a BiA pacemaker (with leads in the RAA and coronary sinus), cardiac output (CO), right (RV) and left ventricular (LV) filling, RA-LA contraction delay [PA(m-t)] and the difference in A wave duration [Adif(m-p)] at the level of the mitral valve (Adurm) and pulmonary veins (Adurp) during RAA, BiA, and LA pacing were examined by echo-Doppler measurements. The atrial pacing site did not affect the CO. LA, but not BiA, pacing resulted in delayed RA contraction in comparison with RAA pacing with significant diminution of the RA contribution to RV filling. With LA pacing, the usual right-to-left atrial contraction sequence was reversed (PA(m-t): 8 +/- 7 ms control; 5 +/- 30 ms RAA; -10 +/- 21 ms BiA; -72 +/- 36 ms LA; LA versus control versus RAA and versus BiA, P < 0.001. LA and BiA pacing prolonged Adurp (LA 186 +/- 52 ms, BiA 180 +/- 45 ms, RAA 153 +/- 49 ms; LA and BiA vs RAA, P < 0.01). Thus Adurp exceeded Adurm [Adif (m-p): control 38 +/- 40 ms, RAA 7 +/- 42 ms, BiA -12 +/- 43 ms, LA -20 +/- 44 ms; control vs RAA, BiA, and LA; and RAA vs LA, P < 0.05]. The study showed that (1) the atrial pacing site has no influence on global cardiac performance; (2) the hemodynamic effect of BiA pacing is not superior to that of RAA pacing, and LA pacing can even be deleterious; (3) LA pacing reverses the usual right-to-left atrial contraction sequence and reduces the RA contribution to RV filling; (4) BiA and LA pacing prolong Adurp due to an altered activation pattern, decreased pulmonary venous return, or increased LA pressure.