A system and corresponding method for steering stimulus pulses to one or more selected cardiac sites are disclosed. An apparatus and corresponding method permit improved capture and easy adjustment of the stimulus pulse when the threshold level changes, without simply increasing stimulus power or replacing the implanted lead. Substantially concurrent pulses may be delivered across one, two or more anode electrodes and a corresponding common or cathode electrode, where the pulse amplitude, pulse duration or pulse phase characteristics of each individual component pulse are adjusted to permit the resulting composite pulse to be steered or directed towards a desired target cardiac site. Different embodiments of the apparatus and corresponding method include those which permit the steering of pacing pulses in the left atrium or in multiple chambers, use of an improved single lead system having electrodes floating in the atrium, steering of atrial pulses to provide an enhancement of a VDD system, steering of atrial or ventricular defibrillation stimuli, and steering stimuli for arrhythmia prevention. In yet other embodiments, the steered pulse system is combined with capture detection and automatic adjustment of the steering parameters.