An ablation assembly to treat target regions of a tissue in organs comprising: - an ablation catheter comprising an elongate shaft having a longitudinal main direction (X-X), said elongate shaft comprising at least a shaft distal portion, said shaft distal portion comprising a shaft distal portion distal end; said ablation catheter comprising an inner lumen arranged within the elongate shaft; said ablation catheter comprising a shaft ablation assembly fixedly disposed at said shaft distal portion, the shaft ablation assembly being configured to deliver both thermal energy for ablating said tissue and non-thermal energy for treating said tissue; - at least a shape setting mandrel disposed within the ablation catheter, the shape setting mandrel being insertable within the inner lumen and removable from the inner lumen, wherein the shape setting mandrel is free to move in respect of the inner lumen avoiding any constraint with said shaft distal portion during the shape setting mandrel insertion, wherein the shape setting mandrel comprises at least a pre-shaped configuration and the shape setting mandrel is reversibly deformable between at least a straight loaded configuration and said pre-shaped configuration, wherein, when the shape setting mandrel is fully inserted in the shaft distal portion, the shape setting mandrel is configured to shape set said shaft distal portion with said pre-shaped configuration, wherein said shape setting mandrel comprises a mandrel proximal portion, wherein said mandrel proximal portion is disposed outside said inner lumen so that said shape setting mandrel is drivable by a user, wherein said elongate shaft comprises a shaft proximal end, wherein said ablation catheter comprises a steering device attached to said shaft proximal end, wherein said ablation catheter comprises an handle, wherein said steering device is connected to said handle and is drivable in rotation with respect to said handle so that a rotation of said steering device with respect to said handle causes a rotation of said elongate shaft. - an ablation catheter comprising an elongate shaft having a longitudinal main direction (X-X), said elongate shaft comprising at least a shaft distal portion, said shaft distal portion comprising a shaft distal portion distal end; said ablation catheter comprising an inner lumen arranged within the elongate shaft; said ablation catheter comprising a shaft ablation assembly fixedly disposed at said shaft distal portion, the shaft ablation assembly being configured to deliver both thermal energy for ablating said tissue and non-thermal energy for treating said tissue; - at least a shape setting mandrel disposed within the ablation catheter, the shape setting mandrel being insertable within the inner lumen and removable from the inner lumen, wherein the shape setting mandrel is free to move in respect of the inner lumen avoiding any constraint with said shaft distal portion during the shape setting mandrel insertion, wherein the shape setting mandrel comprises at least a pre-shaped configuration and the shape setting mandrel is reversibly deformable between at least a straight loaded configuration and said pre-shaped configuration, wherein, when the shape setting mandrel is fully inserted in the shaft distal portion, the shape setting mandrel is configured to shape set said shaft distal portion with said pre-shaped configuration, wherein said shape setting mandrel comprises a mandrel proximal portion, wherein said mandrel proximal portion is disposed outside said inner lumen so that said shape setting mandrel is drivable by a user, wherein said elongate shaft comprises a shaft proximal end, wherein said ablation catheter comprises a steering device attached to said shaft proximal end, wherein said ablation catheter comprises an handle, wherein said steering device is connected to said handle and is drivable in rotation with respect to said handle so that a rotation of said steering device with respect to said handle causes a rotation of said elongate shaft.