Relationship of paroxysmal atrial tachyarrhythmias to volume overload: assessment by implanted transpulmonary impedance monitoring.
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.


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 > or = 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.
Jhanjee
Rajat
R
Cardiac Arrhythmia Center, Cardiovascular Division, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
Templeton
Grant A
GA
Sattiraju
Srinivasan
S
Nguyen
John
J
Sakaguchi
Scott
S
Lu
Fei
F
Ermis
Cengiz
C
Milstein
Simon
S
Van Heel
Laura
L
Lurie
Keith G
KG
Benditt
David G
DG
D000368:Aged; D000465:Algorithms; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D001810:Blood Volume; D002307:Cardiography, Impedance / Q000295:instrumentation*; D017147:Defibrillators, Implantable; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000503:physiopathology