We report a capacitive pressure sensor to be integrated in a FFR catheter. The novelty presented in this work is based on two innovations: (1) VTT surface micromachined process used in fabrication of a ultrathin and narrow pressure sensor element and (2) mounting of the pressure sensor on the catheter sidewall instead of the guide wire enabling thus to use standard guide wires. Two design and fabrication runs were accomplished. The measurement results of the MEMS pressure sensor element correlate well with the calculated and simulated results.