Pulmonary vein contraction before and after radiofrequency ablation for atrial fibrillation.

UNLABELLED: INTRODUCTION: Cardiovascular magnetic resonance imaging (cMRI) may provide a noninvasive method to test for pulmonary vein (PV) isolation after ablation for atrial fibrillation (AF) by detecting changes in PV contraction. METHODS: PV contraction (the maximal percentage change in PV cross-sectional area [CSA] during the cardiac cycle) measured 1 month before and 2 months after PV isolation was compared in 63 PVs from 16 patients with medically refractory AF. Repeat cMRI imaging and invasive catheter mapping was performed prior to repeat PV ablation in 50 PVs from 14 additional patients with recurrent AF. Contraction in PVs with sustained isolation after the initial ablation was compared to contraction in PVs with electrical reconnection to adjacent atrium. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cutoff PV contraction value for prediction of PV-atrial reconnection after ablation. The cutoff value was then prospectively tested in 40 PVs from 12 additional patients. RESULTS: PV contraction decreased after AF ablation (22.4 ± 10% variation in CSA before ablation vs 10.1 ± 8% variation in CSA after ablation, P < 0.00001). PVs with sustained isolation on invasive mapping contracted less than PVs with electrical reconnection to adjacent atrium (13.7 ± 10.6% vs 21.4 ± 9.3%, P = 0.021). PV contraction produced a c-index of 0.74 for prediction of PV-atrial reconnection after ablation and >17% variation in PV CSA predicted reconnection with a sensitivity of 84.6% and specificity of 66.7%. CONCLUSION: PV contraction is reduced by ablation. PV contraction measurement may provide a noninvasive method to test for PV isolation after ablation procedures.

Prevalence and clinical characteristics associated with left atrial appendage thrombus in fully anticoagulated patients undergoing catheter-directed atrial fibrillation ablation.

INTRODUCTION: Catheter-directed atrial fibrillation (AF) ablation is contraindicated among patients with left atrial appendage (LAA) thrombus. The prevalence of LAA thrombus among fully anticoagulated patients undergoing AF ablation is unknown. METHODS AND RESULTS: We retrospectively evaluated the prevalence of LAA thrombus among 192 consecutive patients undergoing AF ablation between July 2006 and January 2009. Seven of 192 patients (3.6%) had evidence of thrombus on transesophageal echocardiogram (TEE) despite being fully anticoagulated on warfarin (international normalized ratio [INR] 2-3) for 4 consecutive weeks prior to echocardiogram. Univariate analysis demonstrated that structural heart disease, large left atrial dimension, and number of AF ablations were associated with thrombus. Three patients with thrombus had paroxysmal AF with normal LV function. CONCLUSION: Despite full anticoagulation, 3.6% of patients undergoing AF ablation had LAA thrombus. We recommend that all patients, regardless of LV function or left atrial size, should undergo preprocedural TEE to exclude the presence of LAA thrombus.

An interesting case of positional hypoxia: the effect of multiple synergistic pathological conditions.

This report describes an elderly patient evaluated for generalized fatigue, dyspnea, presyncopal episodes, and positional hypoxemia. Workup revealed posturally related oxygen desaturation, a patent foramen ovale (PFO), an atrial septal aneurysm, and primary adrenal insufficiency. Normal intracardiac pressures and a right-to-left PFO shunt were present only while the patient was in the upright position. Numerous etiologies of positional right-to-left shunting associated with platypnea-orthodeoxia have been described. Despite advancements in diagnostic and treatment modalities, the pathophysiology of right-to-left shunting with normal intracardiac pressure remains elusive. This report highlights the complexity of positional right-to-left shunting in hypoxemic patients with normal intracardiac pressures and multiple synergistic medical conditions.

Prevalence and determinants of troponin T elevation in the general population.

BACKGROUND: The prevalence and determinants of cardiac troponin T (cTnT) elevation in the general population are unknown, and the significance of minimally increased cTnT remains controversial. Our objective was to determine the prevalence and determinants of cTnT elevation in a large, representative sample of the general population. METHODS AND RESULTS: cTnT was measured from stored plasma samples in 3557 subjects of the Dallas Heart Study, a population-based sample. cTnT elevation (> or =0.01 microg/L) was correlated with clinical variables and cardiac MRI findings. The sample weight-adjusted prevalence of cTnT elevation in the general population was 0.7%. In univariable analyses, cTnT elevation was associated with older age, black race, male sex, coronary artery calcium by electron beam CT, a composite marker of congestive heart failure (CHF), left ventricular hypertrophy (LVH), diabetes mellitus (DM), and chronic kidney disease (CKD) (P<0.001 for each). Subjects with minimally increased (0.01 to 0.029 microg/L) and increased (> or =0.03 microg/L) cTnT had a similar prevalence of these characteristics. In multivariable logistic regression analysis, LVH, CHF, DM, and CKD were independently associated with cTnT elevation. CONCLUSIONS: In the general population, cTnT elevation is rare in subjects without CHF, LVH, CKD, or DM, suggesting that the upper limit of normal for the immunoassay should be <0.01 microg/L. Even minimally increased cTnT may represent subclinical cardiac injury and have important clinical implications, a hypothesis that should be tested in longitudinal outcome studies.

The challenge of defining bleeding among patients with acute coronary syndromes.

Advances in the management of patients with acute coronary syndromes (ACS), specifically, the use of combined pharmacotherapy with antithrombotic and antiplatelet therapies and routine percutaneous coronary intervention (PCI), have greatly reduced rates of thrombotic outcomes and mortality in these patients. However, these same therapies also can increase the risk of bleeding and transfusion use, which are predictive of poor outcomes in patients with ACS. Accurate assessment of the risk-to-benefit ratio for any therapy depends on the use of clinically relevant, preferably standardized, definitions of endpoint events. Unfortunately, clinical trials of antithrombotic therapies have used various definitions for bleeding, most of which were originally developed for trials of fibrinolytic therapy in acute myocardial infarction (MI). These variations in bleeding definitions have complicated cross-study comparisons and assessments of drug class effects. Further, it is unclear whether these definitions remain clinically relevant in the era of routine PCI and aggressive antithrombotic therapy for ACS. Although an argument can be made for development of a standardized bleeding definition, a more prudent approach may be to develop standardized data elements, which can then be used to tailor bleeding definitions according to the goals of future clinical investigations.

Impact of left ventricular dysfunction on hospital mortality among patients undergoing elective percutaneous coronary intervention.

Many patients with systolic dysfunction undergo elective percutaneous coronary intervention (PCI) despite the unknown risk and limited data supporting its use. Therefore, the aim of this study was to evaluate the association between the severity of left ventricular (LV) systolic dysfunction and hospital mortality in patients who undergo elective PCI. A retrospective cohort study was conducted of all patients who underwent elective PCI in New York State in 1998 and 1999. Patients were stratified into 5 groups on the basis of their LV ejection fractions (EFs) before PCI (>55%, 46% to 55%, 36% to 45%, 26% to 35%, and < or =25%). Comparisons of demographic, procedural, and outcome variables were performed, and adjusted odds ratios (ORs) were calculated to evaluate the relation between the EF and hospital mortality. Among 55,709 patients who underwent elective PCI, EFs < or =25%, 26% to 35% and 36% to 45% were present in 3.4%, 7.6%, and 17.4%, respectively. Hospital mortality was 0.3%, 0.2%, 0.6%, 1.2%, and 2.7% in the groups with EFs >55%, 46% to 55%, 36% to 45%, 26% to 35%, and < or =25%, respectively (p <0.001). After multivariate adjustment, an increased risk for hospital mortality was significant for EF groups of 36% to 45% (OR 1.56, 95% confidence interval 1.06 to 2.30), 26% to 35% (OR 2.17, 95% confidence interval 1.42 to 3.31), and < or =25% (OR 3.85, 95% confidence interval 2.46 to 6.01) compared with EF >55%, respectively. In conclusion, this analysis demonstrates that elective PCI is commonly performed in patients with reduced EFs, and the risk for hospital mortality increases as the EF decreases. For patients who undergo elective PCI, an EF < or =45% is associated with higher adjusted hospital mortality. Whether elective PCI in patients with low EFs reduces morbidity and/or mortality over medical therapy alone is unknown.

The impact of race on response to RAAS inhibition.

Retrospective analyses of the Studies of Left Ventricular Dysfunction (SOLVD) and Vasodilator Heart Failure Trials (V-HeFT) have addressed the question of whether angiotensin-converting enzyme (ACE) inhibitors are equally efficacious in black patients and white patients with heart failure. In SOLVD, there was no ethnic difference in the efficacy of enalapril for reducing mortality and preventing the development of heart failure, but enalapril was more effective in whites in reducing hospitalizations. In V-HeFT II, enalapril was more efficacious than the combination of isosorbide dinitrate and hydralazine in whites in reducing mortality, but not in blacks. However, the combination of isosorbide dinitrate and hydralazine may be particularly advantageous in black patients as suggested by V-HeFT I and the recent African American Heart Failure Trial. In aggregate, the available data suggest that ACE inhibitors should remain a cornerstone of therapy for heart failure with a reduced ejection fraction in white patients and black patients.