Results of the Protos Survey: Effectiveness of the New Closed-Loop Pacemakers in Clinical Practice

Summary The new Protos DR/CLS dual-chamber and Protos VR/CLS single-chamber pacemakers have an extended indication and functionality range compared to earlier rate-adaptive pacemaker systems based on monitoring the myocardial contraction dynamics by means of intracardiac impedance measurement. During the Protos survey, 66 patients with DDD(R) or VVI(R) pacemaker indication were followed for 4 weeks after implantation. A total of 60 patients (mean age 72.5 ± 9.9 years, 32 female) with the rate adaptation by means of Closed Loop Stimulation (CLS) activated at hospital discharge were included in the analysis. At the 4-week follow-up, the rate adaptation of 16 out of a total of 43 documented and evaluated exercise tests was classified as adequate. In 26 patients, it was impossible to evaluate the rate adaptation due to a present intrinsic rhythm. In one case, cardiac pacing was observed only at the basic rate despite statistical data of the pacemaker memory that demonstrated a typical histogram with pacing rates higher than the basic rate. Rate adaptation achieved by CLS was comparable to the heart rate variation in chronotropically competent patients with dominating intrinsic rhythm (rest 70.5 ± 10.5 beats/min versus 74.1 ± 13.2 beats/min, 5-min walk test 111.6 ± 22.1 beats/min versus 101.0 ± 19.6 beats/min, stair descending 100.0 ± 7.1 beats/min versus 104.4 ± 20.3 beats/min, stair ascending 106.0 ± 32.1 beats/min versus 109.6 ± 26.0 beats/min). The Protos survey has demonstrated that rate adaptation using the CLS mode in the new Protos DR/CLS dual-chamber and Protos VR/CLS single-chamber pacemakers results in adequate behavior. Additionally, due to a reduction in the effort required to program the device, the follow-up procedure is facilitated.