A multi-chamber implantable heart stimulation device is provided, adapted to inhibit anodal stimulation at a bipolar right chamber lead induced by a unipolar left chamber lead. The device includes a control unit adapted to provide to the unipolar left chamber lead a pace pulse having a trailing edge without a sharp cutoff. The control unit may be adapted to supply the pace pulse to the unipolar left chamber lead without a fast recharge period. The control unit may be adapted to supply to the unipolar left chamber lead a pace pulse having a trailing edge with a gradual decay, a ramp, steps, or a non-linear function. The control unit may be adapted to supply a different waveform to the bipolar right chamber lead than the pace pulse for the unipolar left chamber lead. For example, a conventional pacing pulse may be supplied to the bipolar right chamber lead.