BACKGROUND: Clinical experience suggests that
atrial tachyarrhythmias (ATs) are a frequent
comorbidity in
heart failure patients with
left ventricular systolic dysfunction and that volume overload may increase AT susceptibility. However, substantiating this apparent relationship in free-living patients is difficult. Recently, certain
implantable cardioverter-defibrillators provide, by measuring transpulmonary electric bioimpedance, an index of
intrathoracic fluid status (OptiVol index [OI]). The goal of this study was to determine whether periods of greater
intrathoracic fluid congestion (as detected by OI) correspond with increased AT event
frequency. METHODS AND RESULTS: This analysis retrospectively assessed the relation between AT events and OI estimate of volume overload in patients with
left ventricular systolic dysfunction and OI-capable
implantable cardioverter-defibrillators. OI values were stratified into 3 levels: group 1, <40; group 2, 40 to 60; and group 3, >60. An OI threshold-crossing event was defined as OI>/=60, a value previously associated with clinically significant volume overload. Findings in 59 patients (
mean left ventricular ejection fraction, 24%) with 225 follow-up
visits (
mean, 3.8
visits per patient) were evaluated. AT
prevalence was 73%. AT
frequency (percent of patients
visits with at least 1 episode of AT since previous device interrogation) was greater in group 3 versus group 1 (P=0.0342). Finally, in terms of
temporal sequence, AT episodes preceded OI threshold-crossing event in 43% of incidences, followed threshold-crossing event in 29%, and was simultaneous or indeterminate in the remainder. CONCLUSIONS: These findings not only support the view that worsening
pulmonary congestion is associated with increased AT
frequency in patients with
left ventricular dysfunction but also suggest that AT events may be responsible for
triggering episodic
pulmonary congestion more often than previously suspected.
