Feasibility of using multivector impedance to monitor pulmonary congestion in heart failure patients
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Pulmonary edema (PE) is associated with fluid accumulation in the lungs. Device-based impedance measurements have been used to detect fluid overload prior to hospitalization. However, studies have reported a high false positive rate (FPR). The objective of this study was to develop and test a new multivector impedance-based algorithm that reliably tracks PE clinical events.
We enrolled patients with implanted CRT-Ds in 23 US centers within 2 weeks of device implant. Six-vector impedance data was collected automatically by the CRT-Ds every 30 min during emergency department visits/hospitalizations and every 2 h at all other times. Detection algorithms for cardiac resynchronization therapy defibrillator (CRT-D) and implantable cardiac defibrillator (ICD) devices were developed using those impedance vectors that would be available in corresponding devices and retrospectively evaluated.
There were 75 patients (69 % male), mean age 66 ± 12 years, with a LVEF of 23 ± 6 % and QRS of 149 ± 25 ms. Twenty-one major clinical events occurred over 8.2 ± 2.6 months of follow-up time. CRT-D vector combinations resulted in a sensitivity of 71.4 % (95 % confidence interval 47.8–88.7) and a FPR of 0.56 (0.30–0.94) false positives per patient-year (FPs/pt-yr); ICD vector combinations resulted in a sensitivity of 61.9 % (38.4–81.9) and a FPR of 0.63 (0.36–0.90) FPs/pt-yr. In comparison, the single-vector RVCoil-Can implementation of this algorithm resulted in a sensitivity of 57.1 % (34.0–78.2) and a FPR of 0.74 (0.44–1.12) FPs/pt-yr.
This multivector impedance algorithm was effective in tracking PE clinical events in this patient population. Additional studies are needed to prospectively evaluate the performance of this algorithm in a larger population.
KeywordsHeart failure Implantable device Impedance Pulmonary edema Congestion
Conflict of interest
Philip F. Binkley is connected with St. Jude Medical (Consultancy/Grants/Research Support), James G. Porterfield and Linda M. Porterfield with St. Jude Medical (Grants/Research Support), Scott L. Beau with St. Jude Medical (Consultancies/Research Support), Raffaele Corbisiero with St. Jude Medical (Consultancies/Honorariums, Research Agreements) and Medtronic and Boston Scientific (Honoraria), and G. Stephen Greer with St. Jude Medical (Research Support). Charles J. Love receives compensation for consulting with St. Jude Medical, Boston Scientific and Medtronic
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