A prospective comparison of cardiac imaging using intracardiac echocardiography with transesophageal echocardiography in patients with atrial fibrillation: the intracardiac echocardiography guided cardioversion helps interventional procedures study.

BACKGROUND: The Intracardiac Echocardiography Guided Cardioversion Helps Interventional Procedures study evaluated the concordance of intracardiac echocardiography (ICE) with transesophageal echocardiography (TEE) in patients with atrial fibrillation (AF). METHODS AND RESULTS: Patients with AF undergoing right heart catheterization underwent left atrium (LA) and interatrial septal (IAS) imaging by TEE and ICE. A blinded comparison of the 2 modalities was performed at a core laboratory. Ninety-five patients aged 58 ± 12 years completed the study. The LA was profiled in all patients with both techniques, and concordance for image quality was 96%. LA appendage (LAA) imaging was achieved in 85% with ICE and 96% with TEE. There was no difference in the presence of spontaneous echo contrast between ICE and TEE during LA imaging, but there was a trend toward a greater incidence in the LAA with TEE (P = 0.109). Intracardiac thrombus was uncommonly seen (TEE, 6.9%; ICE, 5.2%). The concordance for the presence or absence of thrombus was 97% in the LA and 92% in the LAA, but the latter was detected more frequently with TEE. IAS imaging was achieved in 91% with ICE and in 97% with TEE (P = 0.177). Concordance for patent foramen ovale and atrial septal aneurysms was 100% and 96%, respectively. A negative ICE examination was associated with absence of dense echo contrast or thrombus on TEE in 86%. CONCLUSIONS: This study provides validation for the use of ICE for LA and IAS imaging. ICE imaging was less sensitive compared to TEE for LAA thrombus identification. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00281073.

Perceived effects on patients' health of participation in the atrial fibrillation follow-up investigation of rhythm management study.

BACKGROUND: Patients' views about participation in clinical trials have been explored using end-of-study questionnaires for various disease entities. However, little is known about why individuals with atrial fibrillation (AF) choose to participate in clinical trials or how they view their research experience. Understanding these perceptions should provide valuable information for future studies in developing methods to enhance enrollment, optimize adherence to therapies, and maximize patient retention. METHODS: The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Study was a randomized trial of rate-control versus rhythm-control for the management of AF. This descriptive ancillary study used a 7-item questionnaire comprising closed and open-ended items that explored: (1) perceptions of benefits from participation, (2) motivation for enrolling, and (3) satisfaction with research staff and operations. RESULTS: A total of 741/1,032 participants (72%) at 34 of 213 participating AFFIRM sites responded, representing 18% of the 4,060 patients enrolled. The mean follow-up of these respondents was 3.8 +/- 1.1 years. Most respondents (91%) felt that they received enough information about AFFIRM before enrolling and that the results would benefit themselves (88%) and others (91%). Most respondents felt study participation improved awareness about AF (90%) and facilitated coordination of their healthcare (89%). Virtually all were satisfied with information received from AFFIRM personnel (96%), and most (98%) reported that they had received "good care." Responses were similar between randomization groups (rate-control or rhythm-control) and between those younger than 65 years and those 65 years or older. Participants in sinus rhythm at last follow-up were more likely to believe that their medical care in AFFIRM was better than what they would otherwise have received, and were more likely to perceive their treatment course as entailing fewer emergency room visits, hospitalizations, and doctor visits. Regularly scheduled appointments and ongoing availability of staff to answer questions appeared to increase participants' confidence and reduce anxiety. CONCLUSIONS: Patients enrolled in a long-term clinical trial for management of AF were overwhelmingly satisfied with participation.

Does intensity of rate-control influence outcome in atrial fibrillation? An analysis of pooled data from the RACE and AFFIRM studies.

AIMS: The AFFIRM and RACE studies showed that rate control is an acceptable treatment strategy for atrial fibrillation (AF). We examined whether strict rate control offers benefit over more lenient rate control. METHODS AND RESULTS: We compared the outcome of patients enrolled in the rate-control arms of AFFIRM and RACE, using data from patients who met a composite of overlapping inclusion and exclusion criteria. We evaluated 1091 patients, 874 from AFFIRM and 217 from RACE. In AFFIRM, the rate-control strategy aimed for a resting heart rate < or =80 bpm and heart rate during daily activity of < or =110 bpm. In RACE, a more lenient approach was taken: resting heart rate <100 bpm. Primary endpoint was a composite of mortality, cardiovascular hospitalization, and myocardial infarction. Mean heart rate across all follow-up visits for patients in AF was lower in AFFIRM (76.1 vs. 83.4 bpm). Event-free survival for the occurrence of the primary endpoint did not differ (64% in AFFIRM vs. 66% in RACE). Patients with mean heart rates during AF within the AFFIRM (< or =80) or RACE (<100) criteria had a better outcome than patients with heart rates > or =100 (hazard ratios 0.69 and 0.58, respectively, for < or =80 and <100 compared with > or =100 bpm). CONCLUSION: Stringency of the approach to rate control, based on the comparison of the AFFIRM and RACE studies, was not associated with an important difference in clinical events.

Risk of proarrhythmic events in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study: a multivariate analysis.

OBJECTIVES: This study examined the risk of proarrhythmic events in patients receiving antiarrhythmic drugs for treatment of atrial fibrillation (AF) according to present-day safety guidelines. BACKGROUND: Advances in understanding the proarrhythmic risk of antiarrhythmic drugs has led to development of safety guidelines for these agents. Such guidelines were used in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study. METHODS: This study was an analysis of the risk of arrhythmic events (arrhythmic death, resuscitated cardiac arrest, sustained ventricular tachycardia (VT), and torsade de pointes VT) in the antiarrhythmic drug arm of the AFFIRM study. Each time an antiarrhythmic drug was begun, it was counted as an exposure to that drug and the risk of an arrhythmic event was calculated. RESULTS: A total of 2,033 patients received 3,030 exposures to antiarrhythmic drugs. Ninety-six arrhythmic events occurred by six years. Patients with a left ventricular ejection fraction <40% had more arrhythmic events. Twelve documented cases of torsade de pointes VT were noted. The incidence of torsade de pointes was 0.6% at five years (95% confidence interval 0.32 to 1.07). CONCLUSIONS: The overall risk of adverse arrhythmic events upon exposure to antiarrhythmic drugs in the AFFIRM study was reasonably low. Strict criteria for the safe use of antiarrhythmic drugs were successful in minimizing proarrhythmic events.

A computational model for the identification of biochemical pathways in the krebs cycle.

We have applied an algorithmic methodology which provably decomposes any complex network into a complete family of principal subcircuits to study the minimal circuits that describe the Krebs cycle. Every operational behavior that the network is capable of exhibiting can be represented by some combination of these principal subcircuits and this computational decomposition is linearly efficient. We have developed a computational model that can be applied to biochemical reaction systems which accurately renders pathways of such reactions via directed hypergraphs (Petri nets). We have applied the model to the citric acid cycle (Krebs cycle). The Krebs cycle, which oxidizes the acetyl group of acetyl CoA to CO(2) and reduces NAD and FAD to NADH and FADH(2), is a complex interacting set of nine subreaction networks. The Krebs cycle was selected because of its familiarity to the biological community and because it exhibits enough complexity to be interesting in order to introduce this novel analytic approach. This study validates the algorithmic methodology for the identification of significant biochemical signaling subcircuits, based solely upon the mathematical model and not upon prior biological knowledge. The utility of the algebraic-combinatorial model for identifying the complete set of biochemical subcircuits as a data set is demonstrated for this important metabolic process.