Pulmonary vein isolation (PVI) is of great importance to achieve rhythm control in patients with atrial fibrillation. Besides catheter-based procedures, the application of high-intensity focused ultrasound (HIFU) can be used for PVI. However, HIFU has been associated with rater low efficacy rates. We report a case of a 73-year old patient, in whom HIFU failed to maintain sinus rhythm but promoted the occurrence of a scar-related atrial tachycardia (AT). Coherent mapping with visualization of velocity vectors allowed the correct interpretation and the targeted ablation of this tachycardia. The coherent mapping function could simplify mapping of scar-related tachycardia in the future.