Apparatus, including a catheter configured to be inserted into an organ of a human body. A plurality of electrodes are deployed on the catheter, the electrodes being configured to transfer radiofrequency (RF) ablation energy to tissue of the organ. The apparatus also includes a power supply configured to supply the RF ablation energy at a level of up to 100 W to each of the plurality of electrodes simultaneously, so as to ablate respective sections of the tissue of the organ in contact with the electrodes.