Introduction: Ventricular arrhythmias are independently related to the mortality risk in patients with heart failure. The wide availability of implantable cardioverter defibrillators (ICD) and Cardiac Resynchronization Therapy (CRT) devices offer an opportunity to clinically correlate the two disease processes.
Hypothesis: We hypothesized that there is association between changes in the intrathoracic impedance as measured by the OptiVol fluid index and episodes of ventricular arrhythmias.
Methods: Non-concordant prospective study of adult patients (age >20) with known heart failure with reduced ejection fraction (EF <35%). Patients were included in the study if they have ICD or CRT device capable of monitoring and storing the intrathoracic impedance; as measured by the OptiVol fluid index. They also must have been receiving interrogation of the device on regular basis, with at least 12 months of cardiac events stored in the device in quarterly intervals. A multivariate random intercepts and random slopes linear regression model were evaluated to estimate any adjusted association between longitudinal changes in the intrathoracic impedance and episodes of ventricular arrhythmias over a 12 month period while taking into account within and between individual variations over time.
Results: A total of 87 patients met the inclusion criteria. The mean age was 73.3 years (±12.7) ,65.5% were males, 56% had ischemic cardiomyopathy as etiology of heart failure, 52% had CRT devices while 48% had ICD. A total of 591 arrhythmic episodes were identified during the follow up period. The unadjusted coefficient for the random intercept/random slopes model for the relationship between impedance and ventricular arrhythmias was ß=0.01; p=0.012; after adjusting for time variations, age, and sex a ß=0.01 (p=0.036) was estimated.
Conclusions: Our study found a significant positive relationship between changes in intrathoracic impedance in patients with heart failure and episodes of ventricular arrhythmias. This suggest that monitoring for changes in the fluid status in patient with heart failure may help predict the occurrence of ventricular arrhythmias. Larger studies are warranted to determine if these findings can be replicated.