Identification and electrophysiological characterization of early left atrial structural remodeling as a predictor for atrial fibrillation recurrence after pulmonary vein isolation.

BACKGROUND: Voltage-guided substrate ablation following pulmonary vein isolation (PVI) improves atrial fibrillation (AF) ablation outcomes. However, by setting an upper voltage cutoff of 0.5 mV during sinus rhythm (SR) to guided substrate ablation using electroanatomic voltage mapping (EAVM), mildly affected low-voltage area (maLVA) may be undetected. We sought to determine the optimal bipolar voltage cutoff to identify maLVA, its electrogram complexity, and the implication on ablation outcome. METHODS AND RESULTS: Left atrial (LA) EAVMs were obtained in patients without AF and structural heart disease (control) to devise a voltage cutoff to identify maLVA. Subsequently, we investigated 100 patients without low-voltage area (LVA) of < 0.5 mV who underwent PVI alone. In our 6 control cohorts, 95% of LA regional bipolar voltage was > 1.17 mV. maLVA, defined as <1.1 mV, was present in 43% of AF patients, associated with higher prevalence of abnormal electrograms (44.1% vs. 4.4%, P < 0.001). During a median of 2.4 years, patients with maLVA had higher recurrence rate (Log-rank P < 0.001), and maLVA was an independent predictor for recurrence in a multivariate analysis (hazard ratio [HR] 3.944; 95% confidence interval [CI] 1.292-12.042; P = 0.016). CONCLUSIONS: A control-derived LA voltage cutoff of <1.1 mV for EAVM in SR reveals maLVA, harboring abnormal electrograms, as an independent predictor for recurrences after PVI alone in patients without LVA (< 0.5 mV). Adjunctive maLVA-guided substrate ablation targeting mildly remodeled and potentially arrhythmogenic LA substrate may further improve the long-term outcome of AF ablation.

Long-Term Outcome of Left Atrial Voltage-Guided Substrate Ablation During Atrial Fibrillation: A Novel Adjunctive Ablation Strategy.

INTRODUCTION: Left atrium (LA) low voltage area (LVA) on 3-D electroanatomic bipolar voltage mapping (EAVM), as a surrogate for scar, is associated with poor AF ablation outcome. We evaluated the long-term outcome of an LVA-guided atrial fibrillation (AF) substrate modification strategy as an adjunct to pulmonary vein isolation (PVI). METHODS AND RESULTS: Two hundred and one consecutive patients with AF (82% persistent/Non-PAF, age 65 years), who underwent EAVM during AF prior to PVI, were divided into 2 groups according to the presence or absence of LVA outside the PV antra, defined as bipolar voltage of <0.5 mV. LVA-guided substrate modification was performed after PVI in patients with LVA. LVA was found in 159 patients (79%). Non-PAF (OR 3.851, P = 0.002) and CHA2 DS2 -VASc score (OR 1.815, P < 0.001) were independent predictors for the LVA. After the index procedure, 144 patients (72%) were free from AF at 12 months. With multiple procedures, 148 patients (74%) during a median follow-up of 3.1 years were free from the recurrence. There was no difference in the recurrence (log-rank P = 0.746), and complications (0% vs. 7%, P = 0.125) between the groups. Neither LVA nor Non-PAF was an independent predictor for the recurrence in a multivariate analysis. CONCLUSIONS: Patients with LVA had an equally favorable long-term ablation outcome compared to those without. As an adjunct to PVI, voltage-guided substrate modification may be an important ablation strategy in patients with LA structural remodeling.

Correlation of Left Atrial Voltage Distribution Between Sinus Rhythm and Atrial Fibrillation: Identifying Structural Remodeling by 3-D Electroanatomic Mapping Irrespective of the Rhythm.

INTRODUCTION: Left atrial (LA) electroanatomical voltage mapping (EAVM) correlates with scar on LGE-MRI and has been used to guide ablation of low voltage area (LVA) in sinus rhythm (SR). We compared EAVM in SR and AF in a cohort of AF patients, and in SR between patients with AF and without AF or structural heart disease (control). METHODS AND RESULTS: Twenty-seven AF patients, 9 with paroxysmal AF (PAF), underwent point-by-point EAVM during SR and AF using same Carto3 geometry. Only adjacent SR-AF points (≤ 5 mm apart) were compared. In addition, 6 control patients were evaluated. There was a linear bipolar voltage correlation between SR and AF (r = 0.707, P < 0.001, Y = 1.515X + 0.786). LA bipolar voltage in patients with PAF was higher than those with Non-PAF in SR (2.24 ± 1.51 vs. 1.56 ± 1.53 mV) and AF (0.81 ± 0.60 vs. 0.58 ± 0.62 mV, both for P < 0.001). The pulmonary vein antra voltage was significantly lower than other LA regions in PAF (1.28 ± 0.79 vs. 2.54 ± 1.50 mV, P < 0.001) and Non-PAF patients (1.13 ± 1.04 vs. 1.86 ± 1.72 mV, P < 0.001), while no voltage differences was found in the control group (P = 0.998). CONCLUSION: There was a linear voltage correlation between SR and AF, suggesting a similar extent of LA fibrotic substrate can be identified on EAVM by adjusting the voltage cutoff. Structural remodeling starts in the PV antra and may progress to other LA regions.

Management of asymptomatic, severe mitral regurgitation.

OPINION STATEMENT: In chronic, severe mitral regurgitation (MR), cardiac function can remain well compensated and patients can remain asymptomatic for many years. Eventually, in most patients, the originally favorable loading conditions give way to unfavorable remodeling, which results in left ventricular (LV) dysfunction and dilation, and ultimately symptoms of pulmonary congestion. Symptomatic, chronic severe MR is a clear indication for surgical correction. However, the optimal management of asymptomatic patients is less clear. While asymptomatic severe MR patients who have developed LV dysfunction or LV dilation warrant surgery, the decision to operate without these findings hinges on the presence of other clinical sequelae, such as atrial arrhythmias and pulmonary hypertension, and on the likelihood of successful mitral valve repair. Controversy exists as to the optimal approach to patients without any of these objective triggers, with some evidence supporting earlier prophylactic surgery and other evidence supporting a "watch and wait" approach. It is our conviction that in absence of an established guideline-based indication for surgical correction, for most asymptomatic patients with chronic severe MR, the preferred approach is close monitoring with serial echocardiography for development of symptoms or other clinical sequelae. However, it is reasonable to consider earlier surgical correction in select asymptomatic patients in whom there is a high likelihood of successful mitral valve repair. In this paper, we comprehensively review all guideline-based management of asymptomatic chronic severe MR, and discuss new evidence that impacts clinical decision-making in these patients.

Pericarditis and pericardial effusion: management update.

OPINION STATEMENT: Prompt recognition of the signs and symptoms of pericardial disease is critical so that appropriate treatments can be initiated. Acute pericarditis has a classical presentation, including symptoms, physical examination findings, and electrocardiography abnormalities. Early recognition of acute pericarditis will avoid unnecessary invasive testing and prompt therapies that provide rapid symptom relief. Non-steroidal anti-inflammatory drugs (NSAIDs) remain first-line therapy for uncomplicated acute pericarditis, although colchicine can be used concomitantly with NSAIDS as the first-line approach, particularly in severely symptomatic cases. Colchicine should be used in all refractory cases and as initial therapy in all recurrences. Aspirin should replace NSAIDS in pericarditis complicating acute myocardial infarction. Systemic corticosteroids can be used in refractory cases or in those with immune-mediated etiologies, although generally should be avoided due to a higher risk of recurrence. Pericardial effusions have many etiologies and the approach to diagnosis and therapy depends on clinical presentation. Pericardial tamponade is a life-threatening clinical diagnosis made on physical examination and supported by characteristic findings on diagnostic testing. Prompt diagnosis and management is critical. Treatment consists of urgent pericardial fluid drainage with a pericardial drain left in place for several days to help prevent acute recurrence. Analysis of pericardial fluid should be performed in all cases as it may provide clues to etiology. Consultation of cardiac surgery for pericardial window should be considered in recurrent cases and may be the first-line approach to malignant effusions, although acute relief of hemodynamic compromise must not be delayed. Constrictive pericarditis is associated with symptoms that mimic many other cardiac conditions. Thus, correct diagnosis is critical and involves identification of pericardial thickening or calcification in association with characteristic hemodynamic alterations using noninvasive and invasive diagnostic approaches. Constrictive physiology may occur transiently and resolve with medical therapy. In chronic cases, definitive therapy requires referral to an experienced surgeon for pericardiectomy.

A 63-year-old woman with a pericardial effusion, bilateral pleural effusions, and ascites: is the whole greater than the sum of its parts?

A 63-year-old female presented with dyspnea, leg edema, and abdominal distention. Exam revealed blood pressure of 104/58, pulse 108/min, jugular venous pressure of 8 cm, no pulsus paradoxus, a pericardial rub, muffled heart sounds, decreased basilar breath sounds, ascites, and ankle edema. Electrocardiogram showed low voltage. Imaging revealed thickened pericardium and a pericardial effusion. Hemodynamic tracings postpericardiocentesis revealed elevated right-sided pressures. The patient was diagnosed with effusive constrictive pericarditis. The case and review of this condition are described. Patients with a pericardial effusion and symptoms unresponsive to pericardiocentesis or with pericardial thickening should undergo evaluation for effusive-constrictive pericarditis.

The influence of an audience response system on knowledge retention: an application to resident education.

OBJECTIVE: The purpose of the study was to compare delivery methods of lecture material regarding contraceptive options by either traditional or interactive lecture style with the use of an audience response system with obstetrics and gynecology residents. STUDY DESIGN: A prospective, randomized controlled trial that included 17 obstetrics and gynecology residents was conducted. Group differences and comparison of pre/posttest scores to evaluate efficacy of lecture styles were performed with the Student t test. Each participant completed an evaluation to assess usefulness of the audience response system. RESULTS: Residents who received audience response system interactive lectures showed a 21% improvement between pretest and posttest scores; residents who received the standard lecture demonstrated a 2% improvement (P = .018). The evaluation survey showed that 82% of residents thought that the audience response system was a helpful learning aid. CONCLUSION: The results of this randomized controlled trial demonstrate the effectiveness of audience response system for knowledge retention, which suggests that it may be an efficient teaching tool for residency education.

Effects of neural network feedback to physicians on admit/discharge decision for emergency department patients with chest pain.

STUDY OBJECTIVE: Neural networks can risk-stratify emergency department (ED) patients with potential acute coronary syndromes with a high specificity, potentially facilitating ED discharge of patients to home. We hypothesized that the use of "real-time" neural networks would decrease the admission rate for ED chest pain patients. METHODS: We conducted a before-and-after trial. Consecutive ED patients with chest pain were evaluated before and after implementation of a neural network in an urban university ED. Data included 40 variables used in neural networks for acute myocardial infarction and acute coronary syndrome. Data were obtained in real time, and neural network outputs were provided to the treating physician while patients were in the ED. On hospital discharge, attending physicians received feedback, including neural network output, their initial clinical impression, cardiac test results, and final diagnosis. The main outcome was the actual admit/discharge decision made before versus after the implementation of the neural network. RESULTS: Before implementation, 4,492 patients were enrolled; after implementation, 432 patients were enrolled. Implementation of the neural network did not decrease the hospital admission rate (before: 62.7% [95% confidence interval (CI) 61.3% to 64.1%] versus after: 66.6% [95% CI 62.2% to 71.0%]). Additionally, the ICU admission rates were not different (11.4% [95% CI 10.5% to 12.3%] versus 9.3% [95% CI 6.6% to 12.0%]). Physician query found that the neural network changed management in only 2 cases (<1%). CONCLUSION: The use of real-time neural network feedback did not influence the admission decision for ED patients with chest pain, most likely because the neural network output was delayed until the return of cardiac markers, and the disposition decision had already been made by that time.

Participation in the academic associate program: effect on medical school admission rate.

OBJECTIVES: Several emergency medicine programs are using premedical students as research assistants for clinical research in the emergency department (ED). These programs have been shown to enhance faculty research productivity, but the effects of these programs on the students' goals have not been assessed. The authors evaluated the effect of the Academic Associate Program (AAP) on medical school acceptance rates. METHODS: From 1997 to 2002, premedical students who attended informational sessions about the AAP completed a 28-item survey including demographic information, educational experiences, career goals, grade point average (GPA), and prior research participation. Premedical students who had a career goal of becoming a physician were included in the study if they matriculated into medical school or changed their career plans by the fall of 2003. Medical school acceptance was determined by contacting students or their parents via telephone and e-mail. Students enrolled in the AAP were compared with Association of American Medical Colleges (AAMC) data to determine whether they were more or less likely to be accepted into medical school. RESULTS: During the study period, 198 students enrolled in the AAP had attained a final disposition with respect to medical school matriculation. Students were a mean age of 22.4 +/- 3.0 years, 55% female, and 43% nonwhite. Most students (91%) were junior year or later with respect to educational level. Prior research experience included being an author on an abstract (25%), being an author on a manuscript (17%), and presenting research at a scientific meeting (14%). The mean GPA ( +/- standard deviation) for Academic Associates was 3.38 ( +/- 0.31). Medical school acceptance rates were 79% for students in the AAP (95% confidence interval [95% CI] = 73.1 to 84.5). This is higher than expected based on AAMC published data with a 49% (95% CI = 48.5 to 49.5) acceptance rate for students with a mean GPA of 3.46. CONCLUSIONS: Compared with AAMC data, students in the AAP have a higher medical school acceptance rate despite a slightly lower GPA. This finding suggests that participation in the program enhances a student's likelihood of matriculating in medical school.

Studies in emergency department data collection: shared versus split responsibility for patient enrollment.

OBJECTIVES: To compare patient enrollment in six clinical studies using shared coverage (24 emergency department [ED] rooms-two students share enrollment responsibility) with enrollment using split coverage (12 rooms each per student). The academic associate (AA) program uses undergraduate students to collect data for clinical studies in the ED by providing double coverage 16 hours/day, seven days/week. Prior studies have shown that this system captures >85% of eligible patients. Methods to obtain closer to 100% enrollment are desired. METHODS: During consecutive 15-day periods with the same 24 AAs, the daily ED census, hours of AA coverage, and enrollment in each of six studies were evaluated prospectively in the ED. Data are presented as means with 95% confidence intervals (CIs). RESULTS: There was no difference between the shared and split enrollment periods with respect to hours of AA coverage (30.3 vs. 30.7 hours/day; p = 0.7) or average daily ED census (133.7 vs. 141.8; p = 0.15). Overall, the percentages of ED patients recruited for study participation were not different depending on whether the split versus shared recruitment strategy was used (907 patients recruited out of 2005 ED patients (45.2%; 95% CI = 43.0 to 47.4) vs. 937 of 2127 (44.0%; 95% CI = 41.9 to 46.1). The 95% CI for the 1.2% difference was -1.8% to 4.2%. Patient enrollments in six individual studies were similar regardless of recruitment strategy. Following the 30-day trial, AAs were surveyed: 17 of 24 (71%) found the split strategy to be "more helpful in enrolling subjects," and 20 of 24 (83%) found split strategy helped them "keep better track" of patients. CONCLUSIONS: Study subject enrollment was not affected by the use of either the shared or split responsibility strategy for recruitment. Students generally preferred the split strategy because it was more helpful and easier to monitor. Therefore, this may be the best option for similar student-oriented data collection programs.