An improved algorithm calculated from intrathoracic impedance can precisely diagnose preclinical heart failure events: Sub-analysis of a multicenter MOMOTARO (Monitoring and Management of OptiVol Alert to Reduce Heart Failure Hospitalization) trial study

Background Ambulatory measurement of intrathoracic impedance (ITI) with an implanted device has potential to assess fluid accumulation in patients with heart failure (HF), but it has failed to reduce HF-related hospitalization because of a high false-positive rate. Objective We aimed to examine whether a modified algorithm (OptiVol 2.0) could reduce false-positive HF events documented in our multicenter trial (MOMOTARO). Methods The MOMOTARO trial assessed the potential that fluid index could predict fluid accumulation and therefore HF. The MOMOTARO trial assessed whether HF events could be detected based on fluid accumulation as assessed by fluid index. We re-analyzed raw data of ITI trends of the threshold-crossing events with the modified algorithm. Results The study consisted of 195 patients who had been implanted with a high-energy device. During a mean follow-up period of 658 ± 165 days, there were 154 primary HF events detected by the previous algorithm (OptiVol 1.0). With the previous algorithm, there was no significant difference in log concentration of brain natriuretic peptide (BNP) between baseline and alert (p = 0.21). Among 150 alerts of the previous algorithm, only 37 reached the threshold by the modified algorithm, and log BNP was significantly higher in these 37 events compared with the baseline value (2.40 ± 0.46 vs. 2.27 ± 0.52, p < 0.01). Conclusion Our simulation study demonstrates that fluid index calculated with the modified algorithm reduces the number of false-positive threshold-crossing HF events and is promising for accurate diagnosis of fluid accumulation in patients.