The current laser atherectomy technologies to treat patients with challenging (to‐cross) total chronic occlusions with a step‐by‐step (SBS) approach (without leading guide wire), are lacking real‐time signal monitoring of the ablated tissues, and carry the risk for vessel perforation. We present first time post‐classification of ablated tissues using acoustic signals recorded by a microphone placed nearby during five atherectomy procedures using 355 nm solid‐state Auryon laser device performed with an SBS approach, some with highly severe calcification. Using our machine‐learning algorithm, the classification results of these ablation signals recordings from five patients showed 93.7% classification accuracy with arterial vs nonarterial wall material. While still very preliminary and requiring a larger study and thereafter as commercial device, the results of these first acoustic post‐classification in SBS cases are very promising. This study implies, as a general statement, that online recording of the acoustic signals using a noncontact microphone, may potentially serve for an online classification of the ablated tissue in SBS cases. This technology could be used to confirm correct positioning in the vasculature, and by this, to potentially further reduce the risk of perforation using 355 nm laser atherectomy in such procedures.