Contribution of atrial contraction to left ventricular filling in patients with sick sinus syndrome on AAI pacing.

Doppler echocardiographic evaluation of the contribution of atrial contraction to left ventricular filling, its determinants and relationship with early diastolic filling was studied in 20 patients with sick sinus syndrome without structural heart disease on AAI pacing over a wide range of physiological atrioventricular delays (PR intervals). The results were compared with 20 normal controls matched for age, sex and heart rate. Left ventricular filling pattern, and the contribution of left atrial contraction to diastolic filling, were similar in the two groups. AAI pacing restores the physiological dynamics of left ventricular filling in patients with sick sinus syndrome without organic heart disease.