The present invention advantageously provides a method and system for cryogenically ablating large areas of tissue within the left atrium. In an exemplary embodiment a cryotherapy device includes a catheter body, a proximal end and a distal end; a first lumen; a second lumen; and an ablation element expandable from a first diameter to a second diameter, the ablation element having a surface portion that conforms to the uneven surface topography of the cardiac tissue. The ablation element can include one or more deformable balloon and/or flexible elements. The surface of the balloon can further be shaped by regulation of pressure within the one or more balloons. In an exemplary method, a tissue ablation device is provided and tissue in the left atrium is ablated with the device, whereby the ablation is created by freezing tissue.