Fujian Qu

Clinical Implications of Brief Device-Detected Atrial Tachyarrhythmias in a Cardiac Rhythm Management Device Population: Results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes

Background: The RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) is a prospective, outcomes-oriented registry designed to document the prevalence of atrial tachycardia and/or fibrillation (AT/AF) of any duration in patients with pacemakers and implantable cardioverter defibrillators (ICDs) and evaluate associations between rigorously adjudicated AT/AF and predefined clinical events, including stroke. The appropriate clinical response to brief episodes of AT/AF remains unclear. Methods: Rigorously adjudicated electrogram (EGM) data were correlated with adjudicated clinical events with logistic regression and Cox models. Long episodes of AT/AF were defined as episodes in which the onset and/or offset of AT/AF was not present within a single EGM recording. Short episodes of AT/AF were defined as episodes in which both the onset and offset of AT/AF were present within a single EGM recording. Results: We enrolled 5379 patients with pacemakers (N=3141) or ICDs (N=2238) at 225 US sites (median follow-up 22.9 months). There were 359 deaths. There were 478 hospitalizations among 342 patients for clinical events. We adjudicated 37 531 EGMs; 50% of patients had at least one episode of AT/AF. Patients with clinical events were more likely than those without to have long AT/AF (31.9% vs. 22.1% for pacemaker patients and 28.7% vs. 20.2% for ICD patients; P<0.05 for both groups). Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF (5.1% vs. 7.9% for pacemaker patients and 11.5% vs. 10.4% for ICD patients; P=0.21 and 0.66, respectively). Conclusions: In the RATE Registry, rigorously adjudicated short episodes of AT/AF, as defined, were not associated with increased risk of clinical events compared with patients without documented AT/AF. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00837798.

Accurate monitoring of intravascular fluid volume: A novel application of intrathoracic impedance measures for the guidance of volume reduction therapy

Background A significant proportion of patients admitted for acute decompensated heart failure (ADHF) that undergo volume reduction therapy are discharged with unchanged or increased bodyweight suggesting that the endpoints for these therapies are not optimally defined. We aimed to identify vectors that can help monitor changes in intravascular fluid volume, that in turn may more accurately guide volume reduction therapy. Methods Data from six different impedance vectors and corresponding changes in intravascular volume derived from changes in hematocrit were obtained from 132 clinical congestion events in 56 unique patients enrolled in a multisite trial of early detection of clinical congestion events (DEFEAT PE). Mixed effects regression models were used to determine the relation between changes in impedance derived from six different vectors and changes in intravascular plasma volume. Results Changes in impedance were negatively associated with changes in plasma volume. Two vectors, the right atrial ring to left ventricular ring and the left ventricular ring to the right ventricular ring, were most closely associated with changes in intravascular plasma volume. Conclusion Impedance vectors derived from a multivector monitoring system reflect changes in intravascular plasma volume. Two of these vectors most closely track changes in plasma volume and may be used to more accurately guide and optimize volume reduction therapy.