ABSTRACT
Right ventricular apical [RVA] pacing has been reported to induce several deleterious effects particularly in the presence of structural heart disease but can also involve patients with normal left ventricular [LV] function. Left atrial [LA] enlargement is one of these effects, but the majority of studies have measured LA dimension rather than volume. The present prospective study was designed to assess the effect of RVA pacing on LA volume in patients with normal LV function. The study comprised 41 consecutive patients with LV ejection fraction >= 45% and LV end diastolic dimension <= 56 mm who underwent single-or dual- chamber pacemaker implantation in RVA and followed for LA volume measurement and pacemaker analysis at least during the ensuing 4.2 months. In all, 21 patients were excluded from the study due to five spontaneous wide QRS complex [>=120msec], one recent acute coronary syndrome,one significant valvular heart disease, three pacing frequency <90%, eight death or losing follow up in three cases. In remaining 20 patients, LA volume ragned from 21 to 54 mm3 with mean of 37.3 +/- 9.7 mm3 prior to pacemaker implantation that increased to 31 to 103 mm3 [54.3 +/- 17.0] during follow-up [P<0.001]. RVA pacing might lead to an increase in LA volume even in patients with normal LV function