A balloon catheter (160, 231, 331, 431, 531, 700) for pulmonary vein isolation comprising: an ablation balloon and a steerable balloon delivery catheter shaft (130, 236, 336, 436, 536, 701) configured to deploy said ablation balloon (130, 236, 336, 436, 536, 701) into a pulmonary vein; the ablation balloon (130, 236, 336, 436, 536, 701) is coupled to a distal end of the steerable balloon delivery catheter shaft (124, 232, 234, 334, 534, 731), and includes a combination of coated and uncoated regions on an outer surface of the ablation balloon (130, 236, 336, 436, 536, 701), the coated and uncoated regions forming an undulating border around a circumference of the ablation balloon (130, 236, 336, 436, 536, 701), the ablation balloon (130, 236, 336, 436, 536, 701) configured to deploy from an undeployed configuration, and engage a tissue wall of the pulmonary vein along the coated and uncoated regions of the ablation balloon (130, 236, 336, 436, 536, 701); a tissue ablation means configured with the ablation balloon (130, 236, 336, 436, 536, 701) to deliver an ablation therapy to the tissue wall of the pulmonary vein in contact with the uncoated region of the ablation balloon (130, 236, 336, 436, 536, 701), and a flexible electronic circuit coupled to and extending across at least a portion of the ablation balloon, the flexible electronic circuit including a plurality of diagnostic electrodes circumferentially distributed around the ablation balloon and electrical traces that electrically couple the diagnostic electrodes to lead wires extending through a length of the catheter shaft. an ablation balloon and a steerable balloon delivery catheter shaft (130, 236, 336, 436, 536, 701) configured to deploy said ablation balloon (130, 236, 336, 436, 536, 701) into a pulmonary vein; the ablation balloon (130, 236, 336, 436, 536, 701) is coupled to a distal end of the steerable balloon delivery catheter shaft (124, 232, 234, 334, 534, 731), and includes a combination of coated and uncoated regions on an outer surface of the ablation balloon (130, 236, 336, 436, 536, 701), the coated and uncoated regions forming an undulating border around a circumference of the ablation balloon (130, 236, 336, 436, 536, 701), the ablation balloon (130, 236, 336, 436, 536, 701) configured to deploy from an undeployed configuration, and engage a tissue wall of the pulmonary vein along the coated and uncoated regions of the ablation balloon (130, 236, 336, 436, 536, 701); a tissue ablation means configured with the ablation balloon (130, 236, 336, 436, 536, 701) to deliver an ablation therapy to the tissue wall of the pulmonary vein in contact with the uncoated region of the ablation balloon (130, 236, 336, 436, 536, 701), and deploy from an undeployed configuration, and engage a tissue wall of the pulmonary vein along the coated and uncoated regions of the ablation balloon (130, 236, 336, 436, 536, 701); a tissue ablation means configured with the ablation balloon (130, 236, 336, 436, 536, 701) to deliver an ablation therapy to the tissue wall of the pulmonary vein in contact with the uncoated region of the ablation balloon (130, 236, 336, 436, 536, 701), and a flexible electronic circuit coupled to and extending across at least a portion of the ablation balloon, the flexible electronic circuit including a plurality of diagnostic electrodes circumferentially distributed around the ablation balloon and electrical traces that electrically couple the diagnostic electrodes to lead wires extending through a length of the catheter shaft.