An aspiration clot retrieval catheter to have profiled guidewire for deliverability that transitions at a proximal joint to a distal tubular section with a lumen for directing aspiration and facilitating the smooth passage of other products in performing mechanical thrombectomy procedures. The joint can have a low-profile proximal strut formed integrally with the distal tubular section and configured to interlock with a distal portion of the guidewire so that there is a smooth transition of stiffness between the guidewire and the tubular portion of the catheter to improve trackability and decrease the likelihood of kinking. The distal tubular section of the proximal joint can also have features to tailor flexibility. The tubular section can be configured to push radially outward to form a seal with an outer catheter to optimize aspiration transmission to the distal mouth of the aspiration clot retrieval catheter.