Plakoglobin immunolocalization as a diagnostic test for arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: A recent study using an anti-plakoglobin antibody and immunofluorescence methods in endomyocardial tissue specimens found that a marked reduction in plakoglobin staining was highly sensitive and specific for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC). The purpose of our study was to determine the diagnostic utility of plakoglobin immunolocalization using more standard immunoperoxidase methods suitable for clinical laboratories. METHODS: Between January 2007 and October 2010, all patients at our center with suspected ARVC underwent noninvasive and genetic testing, right ventricular (RV) angiography, electrophysiologic studies, and endomyocardial biopsy from the RV septum. Several studies using anti-plakoglobin antibodies were performed using standard immunoperoxidase methods at concentrations of 1:50,000 and 1:75,000 after serial dilutions. RESULTS: Among 16 patients, nine patients fulfilled the clinical criteria for ARVC, and seven patients were found to have other cardiac diagnoses. In the initial study (1:50,000) only one of nine ARVC patients showed reduced plakoglobin signal while the others had normal staining. On repeat staining (1:75,000), reduced signal was observed in three of five of the ARVC patients compared to none in controls (four patients did not have adequate tissue for the repeat experiment). CONCLUSION: These results confirm that abnormal plakoglobin staining can differentiate biopsies from patients with ARVC from those with other myopathies, but with low sensitivity. Further, each specimen must be studied at a particular concentration due to variable antibody reactivity. The necessity for such fine-tuning of the reaction, as well as the subjectivity involved in interpretation of the results, would make this method difficult to utilize in routine hospital laboratories.

Heart Rhythm Society Atrial Fibrillation Centers of Excellence Study: A survey analysis of stakeholder practices, needs, and barriers.

BACKGROUND: An integrated, coordinated, and patient-centered approach to atrial fibrillation (AF) care delivery may improve outcomes and reduce cost. OBJECTIVE: The purpose of this study was to gain a better understanding from key stakeholder groups on current practices, needs, and potential barriers to implementing optimal integrated AF care. METHODS: A series of comprehensive questionnaires were designed by the Heart Rhythm Society Atrial Fibrillation Centers of Excellence (CoE) Task Force to conduct surveys with physicians, advanced practice professionals, patients, and hospital administrators. Data collected focused on the following areas: access to care, stroke prevention, education, AF quality improvement, and AF CoE needs and barriers. Survey responses were collated and analyzed by the Task Force. RESULTS: The surveys identified 5 major unmet needs: (1) Standardized protocols, order sets, or care pathways in the emergency department or inpatient setting were uncommon (36%-42%). (2) All stakeholders agreed stroke prevention was a top priority; however, prior bleeding or risk of bleeding was the most frequent barrier for initiation. (3) Patients indicated that education on modifiable causes, AF-related complications, and lowering stroke risk is most important. (4) Less than half (43%) of the health care systems track patients with AF or treatment status. Patients reported that stroke and heart failure prevention and access to procedures were priority areas for an AF CoE. The most common barriers to implementing AF CoE identified by clinicians were administrative support (69%) and cost (52%); administrators reported physical space (43%). CONCLUSION: On the basis of the findings of this study, the Task Force identified high priority areas to develop initiatives to aid the implementation of AF CoE.

Ablation of Supraventricular Tachycardias From Concealed Left-Sided Nodoventricular and Nodofascicular Accessory Pathways.

BACKGROUND: Nodoventricular and nodofascicular accessory pathways (AP) are uncommon connections between the atrioventricular node and the fascicles or ventricles. METHODS: Five patients with nodofascicular or nodoventricular tachycardia were studied. RESULTS: We identified 5 patients with concealed, left-sided nodoventricular (n=4), and nodofascicular (n=1) AP. We proved the participation of AP in tachycardia by delivering His-synchronous premature ventricular contractions that either delayed the subsequent atrial electrogram or terminated the tachycardia (n=3), and by observing an increase in VA interval coincident with left bundle branch block (n=2). The APs were not atrioventricular pathways because the septal VA interval during tachycardia was <70 ms in 3, 1 had spontaneous atrioventricular dissociation, and in 1 the atria were dissociated from the circuit with atrial overdrive pacing. Entrainment from the right ventricle showed ventricular fusion in 4 out of 5 cases. A left-sided origin of the AP was suspected after failed ablation of the right inferior extension of atrioventricular node in 3 cases and by observing a VA increase with left bundle branch block in 2 cases. The nodofascicular and 3 of the nodoventricular AP were successfully ablated from within the proximal coronary sinus (CS) guided by recorded potentials at the roof of the CS, and 1 nodoventricular AP was ablated via a transseptal approach near the CS os. CONCLUSIONS: Left-sided nodofascicular and nodoventricular AP appear to connect the ventricles with the CS musculature in the region of the CS os. Mapping and successful ablation sites can be guided by recording potentials within or near the CS os.

Wide-QRS Complex Tachycardia.

In a man with a wide-QRS complex tachycardia, a history of an inferior left ventricular scar, atrioventricular dissociation during the tachycardia, and a QRS morphology inconsistent with right or left bundle branch block exclude a diagnosis of supraventricular tachycardia with aberrant ventricular conduction due to bundle branch block or ventricular preexcitation and establish a diagnosis of ventricular tachycardia.

Comparison of radionuclide angiographic synchrony analysis to echocardiography and magnetic resonance imaging for the diagnosis of arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable arrhythmia syndrome entailing a high risk of sudden cardiac death. Discernment from benign arrhythmia disorders, particularly right ventricular outflow tract ventricular tachycardia (RVOT VT), may be challenging, providing an impetus to explore alternative modalities that may facilitate evaluation of patients with suspected ARVC. OBJECTIVE: We evaluated the role of equilibrium radionuclide angiography (ERNA) as a diagnostic tool for ARVC. METHODS: ERNA measures of ventricular synchrony-synchrony (S) and entropy (E)-were examined in patients with ARVC (n = 16), those with RVOT VT (n = 13), and healthy controls (n = 49). The sensitivity and specificity of ERNA parameters for ARVC diagnosis were compared with those of echocardiography (ECHO) and cardiovascular magnetic resonance (CMR). RESULTS: ERNA right ventricular synchrony parameters in patients with ARVC (S = 0.91 ± 0.07; E = 0.61 ± 0.1) differed significantly from those in patients with RVOT VT (S = 0.99 ± 0.01 [P = .0015]; E = 0.46 ± 0.05 [P < .001]) and healthy controls (S = 0.97 ± 0.02 [P = .003]; E = 0.48 ± 0.07 [P = .001]). The sensitivity of ERNA synchrony parameters for ARVC diagnosis (81%) was higher than that for ECHO (38%; P = .033) and similar to that for CMR (69%; P = .162), while specificity was lower for ERNA (89%) than that for ECHO and CMR (both 100%; P = .008). CONCLUSION: ERNA right ventricular synchrony parameters can distinguish patients with ARVC from controls with structurally normal hearts, and its performance is comparable to that of ECHO and CMR for ARVC diagnosis. These findings suggest that ERNA may serve as a valuable imaging tool in the diagnostic evaluation of patients with suspected ARVC.

Electrocardiographic comparison of ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy and right ventricular outflow tract tachycardia.

OBJECTIVES: The purpose of this study was to evaluate whether electrocardiographic characteristics of ventricular arrhythmias distinguish patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) from those with right ventricular outflow tract tachycardia (RVOT-VT). BACKGROUND: Ventricular arrhythmias in RVOT-VT and ARVD/C-VT patients can share a left bundle branch block/inferior axis morphology. METHODS: We compared the electrocardiographic morphology of ventricular tachycardia or premature ventricular contractions with left bundle branch block/inferior axis pattern in 16 ARVD/C patients with that in 42 RVOT-VT patients. RESULTS: ARVD/C patients had a significantly longer mean QRS duration in lead I (150 ± 31 ms vs. 123 ± 34 ms, p = 0.006), more often exhibited a precordial transition in lead V(6) (3 of 17 [18%] vs. 0 of 42 [0%] with RVOT-VT, p = 0.005), and more often had at least 1 lead with notching (11 of 17 [65%] vs. 9 of 42 [21%], p = 0.001). The most sensitive characteristics for the detection of ARVD/C were a QRS duration in lead I of ≥120 ms (88% sensitivity, 91% negative predictive value). QRS transition at V(6) was most specific at 100% (100% positive predictive value, 77% negative predictive value). The presence of notching on any QRS complex had 79% sensitivity and 65% specificity of (55% positive predictive value, 85% negative predictive value). In multivariate analysis, QRS duration in lead I of ≥120 ms (odds ratio [OR]: 20.4, p = 0.034), earliest onset QRS in lead V(1) (OR: 17.0, p = 0.022), QRS notching (OR: 7.7, p = 0.018), and a transition of V(5) or later (OR: 7.0, p = 0.030) each predicted the presence of ARVD/C. CONCLUSIONS: Several electrocardiographic criteria can help distinguish right ventricular outflow tract arrhythmias originating from ARVD/C compared with RVOT-VT patients.

Internal medicine physicians' perceptions regarding rate versus rhythm control for atrial fibrillation.

Atrial fibrillation (AF) is often managed by general internal medicine physicians. Available data suggest that guidelines regarding AF management are often not followed, but the reasons for this remain unknown. The aim of this study was to assess the knowledge and beliefs of internists regarding strategies to treat AF. A national electronic survey of internal medicine physicians regarding their perceptions of optimal AF management, with an emphasis on the rationale for choosing a rhythm- or rate-control strategy, was conducted. One hundred forty-eight physicians from 36 different states responded (representing > or =19% of unique e-mails opened). Half the respondents reported managing their patients with AF independently without referral to cardiologists. Seventy-three percent of participants believed that a rhythm-control strategy conveys a decreased stroke risk, 64% believed that there is a mortality benefit to rhythm control, and 55% thought that it would help avoid long-term anticoagulation. Comparing those who preferred a rhythm-control strategy to everyone else, those who favored rhythm control statistically significantly more often believed that rhythm control reduces the risk for stroke (96% vs 67%, p = 0.009) and that rhythm control allows the discontinuation of anticoagulation therapy (76% vs 49%, p = 0.045). In conclusion, contrary to available data in clinical trials and recent guidelines regarding the rationale for choosing a rhythm-control strategy in treating patients with AF, most study participants believed that rhythm control decreases stroke risk, decreases mortality, and allows the discontinuation of anticoagulation therapy. These prevalent misconceptions may substantially contribute to guideline nonadherence.