An elongated monopolar or bipolar coronary vein lead having a reduced outer diameter and especially adapted to be advanced into a selected coronary vein for delivering a pacing signal to a predetermined region of a patient's heart, such as the left ventricle. A method of using the lead for pacing a patient's heart in the treatment of heart failure is also described. The method for pacing the heart includes advancing the coronary vein lead through both the coronary sinus and into a selected coronary vein of a patient's heart, connecting the lead to an electrical pacing source and applying electrical stimulation to a particular chamber of the patient's heart via the implanted lead. The lead includes a flexible tip and transition ring that enhances the ability to guide the lead through the coronary veins.