Incidence and risk factors for symptomatic heart failure after catheter ablation of atrial fibrillation and atrial flutter.

AIMS: To determine the incidence and risk factors for development of symptomatic heart failure (HF) following catheter ablation for atrial fibrillation (AF) and atrial flutter. METHODS AND RESULTS: We prospectively enrolled consecutive patients undergoing pulmonary vein isolation (PVI) or cavotricuspid isthmus (CTI) ablation between November 2013 and June 2014. Post-discharge symptoms were assessed via telephone follow-up and clinic visits. The primary outcome was symptomatic HF requiring treatment with new/increased diuretic dosing. Secondary outcomes were prolonged index hospitalization and readmission for HF ≤30 days. Univariate and multivariable logistic regressions were used to assess the relationship between patient/procedural characteristic and post-ablation HF. Among 111 PVI patients [median age 62.0 years; left ventricular ejection fraction (LVEF) 55%], 29 patients (26.1%) developed symptomatic HF, 6 patients (5.4%) required prolonged index hospitalization, and 8 patients (7.2%) were readmitted for HF. In univariate analyses, persistent AF [odds ratio (OR) 2.97, P = 0.02], AF at start of the procedure (OR 2.99, P = 0.01), additional ablation lines (OR 11.07, P < 0.0001), and final left atrial pressure (OR 1.10 per 1 mmHg increase, P = 0.02) were associated with HF development. Peri-procedural diuresis, net fluid balance, and LVEF were not correlated. In multivariable analyses, only additional ablation lines (ORadj 9.17, P = 0.007) were independently associated with post-ablation HF. Six patients (16.7%) developed HF after CTI ablation. CONCLUSION: A 26.1% of patients undergoing PVI and 16.7% of patients undergoing CTI ablation developed symptomatic HF when prospectively and uniformly assessed. 12.6% of patients experienced prolonged index hospitalizations or readmission for management of HF within 1 week after PVI. Improved understanding of risk factors for post-ablation HF may be critical in developing strategies to address during AF ablation.

Acute performance of a right ventricular automatic pacing threshold algorithm for implantable defibrillators.

INTRODUCTION: Automatic pacing threshold (AT) testing with threshold trending and output adjustment may simplify follow-up and improve cardiac rhythm device longevity. The objective of this study was to evaluate the performance of a new right ventricular (RV) AT algorithm for implantable cardioverter defibrillators (ICDs) using RVcoil to Can evoked response sensing. METHOD: Patients undergoing ICD, with or without cardiac resynchronization therapy device, implant, replacement, or upgrade were enrolled. A pulse generator emulator (Can) was temporarily placed in the device pocket. An external pacing system (Boston Scientific, St. Paul, MN, USA) with customized software was used for performing threshold tests and data acquisition. RV manual threshold and up to four AT tests using various pacing parameters were conducted. The threshold measurement and the capture detection performance of the RV AT tests were evaluated through comparison with visual examination of surface electrocardiogram. RESULTS: Data from 43 patients were analyzed. A total of 158 AT tests were performed, in which 144 AT tests (91.1%) measured correct threshold values. No consecutive asystolic noncaptured beats were observed in any AT tests, and none of the AT tests resulted in incorrectly low threshold measurements. The difference between manual and AT measurements was -0.05 ± 0.43 V. The accuracy for detecting capture and noncaptured beats were 95% and 99%, respectively. CONCLUSION: The RVcoil to Can evoked response sensing based RV AT algorithm can reliably measure pacing threshold for ICDs, including CRT-Ds.

Impact of High-Power Short-Duration Radiofrequency Ablation on Long-Term Lesion Durability for Atrial Fibrillation Ablation.

OBJECTIVES: The goal of this study was to compare lesion durability between high-power short-duration (HP-SD) and moderate-power moderate-duration (MP-MD) ablation strategies. BACKGROUND: HP-SD radiofrequency ablation (RFA) was developed to improve pulmonary vein isolation (PVI) by reducing the effect of catheter instability inherent to MP-MD ablation strategies. However, its long-term effect on lesion durability for the treatment of atrial fibrillation is unknown. METHODS: Patients with atrial fibrillation (n = 112) underwent PVI using HP-SD ablation (45 to 50 W, 8 to 15 s) with contact force-sensing open irrigated catheter. Cavotricuspid isthmus, mitral annular, and roof lines were permitted. A control group (n = 112) underwent ablation using MP-MD ablation (20 to 40 W, 20 to 30 s) with similar technology. Chronic PV reconnection was examined in patients who required a redo procedure (HP-SD ablation, n = 18; MP-MD ablation, n = 23). RESULTS: The rate of PVI at the completion of the initial encirclement was similar between the HP-SD and MP-MD ablation strategies (90.2% vs. 83.0%; p = 0.006). The HP-SD strategy required shorter RFA time (17.2 ± 3.4 min vs. 31.1 ± 5.6 min; p < 0.001). The incidence of chronic PV reconnection was lower with HP-SD ablation (16.6% vs. 52.2%; p = 0.03). Areas of chronic reconnection were associated with catheter motion ≥1 mm for ≥50% application duration. In a higher proportion of HP-SD applications, catheter motion was <1 mm during ≥50% duration (88.6% vs. 72.8%; p < 0.001), allowing energy delivery with greater stability. Both ablation strategies were effective for cavotricuspid isthmus; however, the HP-SD strategy was less effective for mitral annular lines, requiring ablation at lower power for longer duration to avoid steam pops. CONCLUSIONS: HP-SD ablation may improve PVI durability, and it shortens RFA time. However, ablation in thicker myocardium often requires lower power applied for longer duration, allowing deeper lesions without tissue overheating.

Performance of dedicated versus integrated bipolar defibrillator leads with CRT-defibrillators: results from a Prospective Multicenter Study.

INTRODUCTION: Right ventricular (RV) anodal stimulation may occur in cardiac resynchronization therapy defibrillators (CRT-D) when left ventricular (LV) pacing is configured between the LV lead and an electrode on the RV defibrillator lead. RV defibrillator leads can have a dedicated proximal pacing ring electrode (dedicated bipolar) or utilize the distal shocking coil as the proximal pacing electrode (integrated bipolar). This study compares the performance of integrated versus dedicated leads with respect to anodal stimulation incidence, sensing, and inappropriate ventricular tachyarrhythmia detection in patients implanted with CRT-D. METHODS: Two hundred ninety-two patients were randomly assigned to receive dedicated or integrated bipolar RV leads at the time of CRT-D implantation. Patients were followed for 6 months. RESULTS: Patients with dedicated bipolar RV leads exhibited markedly higher rates of anodal stimulation than did patients with integrated leads. The incidence of anodal stimulation was 64% at implant for dedicated bipolar RV leads compared to 1% for integrated bipolar RV leads. The likelihood of anodal stimulation in patients with dedicated leads fell progressively during the 6-month follow-up (51.5%), but always exceeded the incidence of anodal stimulation in patients with integrated leads (5%). Clinically detectable undersensing and oversensing were very unusual and did not differ significantly between lead designs. There were no inappropriate ventricular tachyarrhythmia detections for either lead type. CONCLUSION: Integrated bipolar RV defibrillator leads had a significantly lower incidence of RV anodal stimulation when compared to dedicated bipolar RV defibrillation leads, with no clinically detectable oversensing or undersensing, and with no inappropriate ventricular tachyarrhythmia detections for either lead type.

Atrial fibrillation therapy in patients with a CRT defibrillator with wireless telemetry.

BACKGROUND: Atrial fibrillation (AF) is a major cause of morbidity and mortality, especially in patients with congestive heart failure. OBJECTIVES: The purposes of this international, prospective multicenter study were to evaluate the efficacy of atrial shock therapy in patients with a cardiac resynchronization therapy defibrillator (CRT-D) and to evaluate the safety of the new CRT-D. The effectiveness of a new wireless telemetry system was also evaluated. METHODS: A total of 282 patients, without permanent AF, who had indications for a CRT-D were included. Atrial shock therapy was tested on both spontaneous and induced AF episodes. The effectiveness of the Medtronic wireless telemetry system (Conexus; Medtronic Inc., Minneapolis, MN, USA) was also tested. Secondary endpoints included the heart failure Clinical Composite Response, system performance evaluation, and adverse event summary. RESULTS: Atrial shock therapy was successful in 168 of 171 episodes (98.2%). Of these, 138 episodes were induced and 33 were spontaneous. Successful cardioversion occurred in 137 of the 138 induced-AF episodes (86.1% with 12 joule (J), 13.1% with 24 J, and 0.7% with 35 J). During the first 3 months of implant, there were 43 system-related complications in 37 subjects out of 278 subjects. There were 1,999 Conexus telemetry uses recorded during this study. This includes 282 uses during the implant procedure. There were no cases of complete loss of telemetry or any adverse events reported using this system. CONCLUSION: We achieved an atrial shock efficacy of 98.2% in patients who met standard CRT-D indications. The wireless telemetry performed well with no reported unanticipated adverse device effects.

Computed tomography-fluoroscopy overlay evaluation during catheter ablation of left atrial arrhythmia.

AIMS: Proper visualization of left atrial (LA) and pulmonary vein (PV) anatomy is of crucial importance during atrial fibrillation (AF) ablation. This two-centre study evaluated a new automatic computed tomography (CT)-fluoroscopy overlay system (EP navigator, Philips Medical Systems, Best, The Netherlands) and the accuracy of different registration methods. METHODS AND RESULTS: Fifty-six consecutive patients (age: 56 +/- 14) with symptomatic AF underwent contrast CT of the LA/PV prior to ablation. Three registration methods were evaluated and validated by comparison with LA angiography: (i) catheter registration: the placement of catheters in identifiable anatomical structures; (ii) heart contour: based on aligning the fluoroscopy heart contours and the 3D-rendered CT volume; and (iii) spine registration: based on automatically aligning the segmented CT spine on fluoroscopy. Computed tomography segmentation was achieved in all but one patient due to motion artefacts. The mean duration of segmentation was 10 min and average registration lasted 7 min. Catheter and heart contour registration were highly accurate (discrepancy of 1.3 +/- 0.6 and 0.3 +/- 0.5 mm, respectively) when compared with spine registration (17 +/- 9 mm, P < 0.05). The EP navigator was helpful during trans-septal puncture, gave an internal view of the atria and allowed tracking of ablation lesions. CONCLUSION: The EP navigator enabled accurate live integration of CT images and real-time fluoroscopy. Registration utilizing catheter placement or heart contours was stable and reliable.

Remote magnetic versus manual catheter navigation for ablation of supraventricular tachycardias: a randomized, multicenter trial.

INTRODUCTION: The potential benefits of remote robotic navigation for catheter ablation procedures have not been demonstrated in controlled clinical trials. The purpose of this study was to compare remote magnetic catheter navigation to manual navigation for the ablation of common supraventricular arrhythmias. METHODS AND RESULTS: Patients with supraventricular arrhythmias due to atrioventricular (AV) nodal reentry, accessory pathways, or undergoing AV junctional ablation for complete heart block were randomized in a 3:1 ratio between magnetic (Niobe system and Helios II catheter, Stereotaxis, Inc., St. Louis, MO) and manual navigation for radiofrequency ablation at 13 centers. The primary endpoint of the study was total fluoroscopic time. Fifty-six patients were randomized to magnetic navigation and 15 to manual navigation. AV nodal reentry was the most common arrhythmia in both groups. Total fluoroscopy time was reduced in the magnetic navigation group (median 17.8 minutes, interquartile (IQ) range 9.9,27.8 minutes) compared to manual navigation (27.1, IQ 19.0,48.0, P < 0.05). The acute success rates (91% for magnetic and 87% for manual navigation, P > 0.05) did not differ between groups. The number of lesions delivered was less for magnetic navigation (6, IQ 4,9 vs 10, IQ 7, 26, P < 0.05). Total procedure time (median 151, IQ 111, 221 minutes magnetic and 151, IQ 110, 221 minutes manual) and complication rates (5.4% patients magnetic and 6.7% patients manual) were similar between the groups (both P > 0.05). CONCLUSIONS: Remote magnetic catheter navigation reduces fluoroscopic time and radiofrequency lesion deliveries for the ablation of common supraventricular arrhythmias compared to manual catheter navigation.

Remote magnetic navigation system provides a superior catheter stability in acquisition of His bundle electrogram.

INTRODUCTION: Catheter stability is a key prerequisite for a successful EP procedure. Remote magnetic navigation system (RMNS) was recently introduced for the manipulation of EP catheters. It may provide an improved catheter stability but this has not been tested prospectively. We performed a prospective cross-over study which compares the amplitude and stability of the His-electrogram obtained by catheters using RMNS vs conventional manual catheter placement. METHODS: His-electrograms were continuously recorded for 3 min with a conventional His mapping catheter and magnetically tipped catheter capable of alignment in the direction of an externally controlled magnetic field (0.08-0.1 Tesla) in the same patient. First 100 beats of each recording were used for data analysis. The amplitudes of each set of His-electrograms were measured and compared in microvolts. Coefficient of variation of the measured His-signal amplitude was calculated for each beat. Miller's test for the equality of the coefficients of variation and Levene's test of homogeneity of variance were used for statistical analysis. RESULTS: Fourteen patients (6 males; aged 48+/-25 years) were included in the study. His-electrograms were more stable and homogenous with RMNS than manual method in 10/14 patients. Pooled variance of all RMNS recordings was significantly less than pooled variance of manual recordings (p=0.01). CONCLUSION: His-electrogram recording using RMNS is more stable and homogeneous than traditional manual method in most patients. These data indicate a superior catheter stability with RMNS.

Baseline myocardial perfusion predicts response to cardiac resynchronization therapy: a prospective observational study.

PURPOSE: We prospectively determined whether preimplant myocardial perfusion imaging (MPI) predicts outcome with biventricular pacing (BiVP). METHODS: Single-photon emission computed tomography (SPECT) MPI, left ventricular (LV) volumes, ejection fraction (EF), 6-min hall walk (6MW) were assessed at baseline and at 4 months in 19 patients with ischemic cardiomyopathy undergoing BiVP. Clinical and hemodynamic responses were correlated with MPI. RESULTS: Lower global myocardial scar burden predicted hemodynamic response to BiVP, while higher burden was associated with poor response. Clinical improvement with BiVP occurred in 12 (63%) of the patients. Clinical BiVP responders had lower rest/stress MPI score difference. There was a close negative correlation between MPI reversibility and increased 6MW distance. CONCLUSIONS: Baseline MPI is associated with clinical and hemodynamic response to BiVP: greater myocardial scar burden is predictive of poor hemodynamic response, while higher ischemic burden is predictive of poor clinical response. There is a differential response to BiVP by clinical and hemodynamic criteria.

Three-dimensional rotational angiography of the left atrium and esophagus--A virtual computed tomography scan in the electrophysiology lab?

BACKGROUND: Three-dimensional (3D) reconstruction of the heart and surrounding structures has been supplementing traditional two-dimensional imaging to guide diagnostic and therapeutic electrophysiologic procedures. Current methods using computed tomography (CT)/magnetic resonance imaging (MRI) reconstruction have certain limitations. OBJECTIVE: We investigated the feasibility of rotational angiography (RA) combined with simultaneous esophagogram to create an intraprocedural 3D reconstruction of the left atrium (LA) and the esophagus. METHODS: Rotational angiography was performed. Contrast was injected via a pigtail catheter positioned in the left or right pulmonary artery to achieve a levophase venous cycle opacification of the ipsilateral pulmonary veins and adjacent LA. Simultaneous administration of oral contrast allowed a 3D reconstruction of the esophagus in the same image. Qualitative and quantitative comparison between the intraprocedural 3D RA and a remote CT scan was performed in 11 consecutive patients undergoing ablation for atrial fibrillation. RESULTS: Adequate visualization of the pulmonary veins, adjacent posterior LA, and esophagus was achieved in 10 patients. Determination of pulmonary transit time to guide the initiation of RA resulted in better-quality imaging. A close correlation between 3D RA and CT was found. Based on close proximity between the LA and esophagus, the ablation procedure was modified in three patients. CONCLUSIONS: Three-dimensional RA of the LA and esophagus is a promising new method allowing intraprocedural 3D reconstruction of these structures comparable in quality to a CT scan. Further studies refining the method are justified because it could eliminate the need for CT/MRI scans before ablation.

Evaluation of left atrial and posterior mediastinal anatomy by multidetector helical computed tomography imaging: relevance to ablation.

INTRODUCTION: Increasing use of catheter ablation in the left atrium (LA) requires understanding of substrate anatomy, especially with regard to potential damage to adjacent structures. METHODS AND RESULTS: We reviewed multidetector helical computed tomography (MDCT) imaging on 42 subjects, 26 imaged before planned LA ablation for atrial fibrillation (AF), and 16 without AF. LA volume and dimensions were larger in patients with AF (p < 0.05) and the spine and aorta (Ao) impressed the LA more frequently in the AF group. The esophagus (Eo) was the predominant feature on the posterior LA wall, contacting it in all patients. The Ao was in contact with the LA body or the left inferior pulmonary vein (PV) in 32 (76%) of 42 cases, and in 10 it ran along an indentation on the posterior aspect of the LA. The coronary sinus was adjacent to LA ablation sites, the azygos vein was rarely adjacent to those sites, and the left bronchus abutted the PV ostium but not the LA. Two patients had findings that directly impacted the ablation procedure: one patient had a dilated fluid filled Eo with esophageal stricture and underwent nasogastric decompression before ablation, and one was discovered to have an anomalous PV and underwent surgical repair. CONCLUSIONS: MDCT imaging identifies structures adjacent to the LA, which could be affected by ablation. Posterior LA topography can be influenced by the position of the Ao or by the proximity of the spine. Preprocedural imaging can characterize anatomic structures that could be vulnerable during ablation, and detect unusual pathology that can affect the treatment plan.

Evaluation of a novel high-resolution mapping technology for ablation of recurrent scar-related atrial tachycardias.

BACKGROUND: Rhythmia is a new technology capable of rapid and high-resolution mapping. However, its potential advantage over existing technologies in mapping complex scar-related atrial tachycardias (ATs) has not yet been evaluated. OBJECTIVE: The purpose of this study was to examine the utility of Rhythmia for mapping scar-related ATs in patients who had failed previous ablation procedure(s). METHODS: This multicenter study included 20 patients with recurrent ATs within 2 years after a previous ablation procedure (1.8 ± 0.7 per patient). In all cases, the ATs could not be adequately mapped during the index procedure because of scar with fractionated electrograms, precluding accurate time annotation, frequent change in the tachycardia in response to pacing, and/or degeneration into atrial fibrillation. These patients underwent repeat mapping and ablation procedure with Rhythmia. RESULTS: From a total of 28 inducible ATs, 24 were successfully mapped. Eighteen ATs (75%) terminated during radiofrequency ablation and 4 (16.6%) with catheter pressure or entrainment from the site of origin or isthmus. Two ATs that were mapped to the interatrial septum slowed but did not terminate with ablation. In 21 of 24 ATs the mechanism was macroreentry, while in 3 of 24 the mechanism was focal. Interestingly, in 5 patients with previously failed ablation of an allegedly "focal" tachycardia, high-resolution mapping demonstrated macroreentrant arrhythmia. The mean mapping time was 28.6 ± 17 minutes, and the mean radiofrequency ablation time to arrhythmia termination was 3.2 ± 2.6 minutes. During a mean follow-up of 7.5 ± 3.1 months, 15 of 20 patients (75%) were free of AT recurrences. CONCLUSION: The Rhythmia mapping system may be advantageous for mapping complex scar-related ATs.

Long-Term Success of Irrigated Radiofrequency Catheter Ablation of Sustained Ventricular Tachycardia: Post-Approval THERMOCOOL VT Trial.

BACKGROUND: Radiofrequency catheter ablation is used to treat recurrent ventricular tachycardia (VT). OBJECTIVES: This study evaluated long-term safety and effectiveness of radiofrequency catheter ablation using an open-irrigated catheter. METHODS: Patients with sustained monomorphic ventricular tachycardia associated with coronary disease were analyzed for cardiovascular-specific adverse events within 7 days of treatment, hospitalization duration, 6-month sustained monomorphic ventricular tachycardia recurrence, quality of life measured by the Hospital Anxiety and Depression Scale, long-term (1-, 2-, and 3-year) survival, symptomatic VT control, and amiodarone use. RESULTS: Overall, 249 patients, mean age 67.4 years, were enrolled. The cardiovascular-specific adverse events rate was 3.9% (9 of 233) with no strokes. Noninducibility of targeted VT was achieved in 75.9% of patients. Post-ablation median hospitalization was 2 days. At 6 months, 62.0% (114 of 184) of patients had no sustained monomorphic ventricular tachycardia recurrence; the proportion of patients with implantable cardioverter-defibrillator shocks decreased from 81.2% to 26.8% (p < 0.0001); the frequency of VT in implantable cardioverter-defibrillator patients with recurrences was reduced by ≥50% in 63.8% of patients; and the proportion with normal Hospital Anxiety and Depression Scale scores increased from 48.8% to 69.1% (p < 0.001). Patient-reported VT remained steady for 1, 2, and 3 years at 22.7%, 29.8%, and 24.1%, respectively. Amiodarone use and hospitalization decreased from 55% and 77.2% pre-ablation to 23.3% and 30.7%, 18.5% and 36.7%, 17.7% and 31.3% at 1, 2, and 3 years, respectively. CONCLUSIONS: Radiofrequency catheter ablation reduced implantable cardioverter-defibrillator shocks and VT episodes and improved quality of life at 6 months. A steady 3-year nonrecurrence rate with reduced amiodarone use and hospitalizations indicate improved long-term outcomes. (NaviStar ThermoCool Catheter for Endocardial RF Ablation in Patients With Ventricular Tachycardia [THERMOCOOL VT]; NCT00412607).

Potential proarrhythmic effect of biventricular pacing: fact or myth?

BACKGROUND: Hemodynamic improvement from biventricular pacing is well documented; however, its electrophysiologic effects have not been systematically studied. Sporadic case reports suggest a proarrhythmic effect of biventricular pacing resulting primarily in polymorphic ventricular tachycardia/ventricular fibrillation (VT/VF). OBJECTIVES: The purpose of this study was to report a series of patients in whom implantation of a biventricular system resulted in VT/VF storm with predominance of monomorphic VT. METHODS: In a retrospective analysis of all biventricular implants over a 4-year period at a single medical center, we identified 5 of 145 patients (3.4%) who developed VT/VF after they were upgraded to a biventricular system. All patients were male, age 71 +/- 8 years, with ejection fraction of 0.25 +/- 0.1. Four of five patients had ischemic cardiomyopathy. RESULTS: All patients developed incessant VT/VF within 1 week of implantation. Monomorphic VT of single morphology was noted in 3 of 5 patients, monomorphic VT of multiple morphologies in 1, and polymorphic VT/VF in 1. VT was managed by temporary discontinuation of biventricular pacing in all patients, amiodarone in 3 of 5, sotalol in 1, and beta-blocker in 1. During 11 +/- 7 months of follow-up, 4 of 5 patients remain alive and are arrhythmia-free. CONCLUSION: Biventricular pacing may result in precipitation of VT/VF storm in a minority of patients with prior history of VT/VF. This may be the first case series reporting both monomorphic and polymorphic VT after an upgrade to a system with biventricular pacing capabilities. The arrhythmias can be managed by conventional therapy and may require temporary discontinuation of left ventricular pacing. This observation is relevant to patients receiving a biventricular pacemaker without an implantable cardioverter-defibrillator backup.

Intravenous lidocaine versus intravenous amiodarone (in a new aqueous formulation) for incessant ventricular tachycardia.

The effectiveness of intravenous amiodarone for the treatment of incessant (shock resistant) ventricular tachycardia (VT) has not been established. This study evaluated the efficacy of a water-soluble amiodarone preparation or lidocaine for the treatment of shock-resistant VT. The trial was a double-blinded parallel design. Patients were randomized to receive up to 2 boluses of either 150 mg intravenous amiodarone or 2 boluses of 100 mg lidocaine followed by a 24-hour infusion. If the first assigned medication failed to terminate VT, the patient was crossed over to the alternative therapy. Twenty-nine patients were randomized to the study (18 received amiodarone and 11 received lidocaine). There were no significant differences between groups with regard to baseline characteristics. Immediate VT termination was achieved in 14 patients (78%) with amiodarone versus 3 patients (27%) on lidocaine (p <0.05). After 1 hour, 12 patients (67%) on amiodarone and 1 patient (9%) on lidocaine were alive and free of VT (p <0.01). Amiodarone had a 33% drug failure rate, whereas there was a 91% drug failure rate for lidocaine. The 24-hour survival was 39% on amiodarone and 9% on lidocaine (p <0.01). Drug-related hypotension with aqueous amiodarone was less frequent than with lidocaine. This study found that amiodarone is more effective than lidocaine in the treatment of shock-resistant VT.

Lack of a hypotensive effect with rapid administration of a new aqueous formulation of intravenous amiodarone.

Hypotension is the most frequent adverse event reported with intravenous amiodarone. Hypotension has been attributed to the vasoactive solvents of the standard formulation (Cordarone IV) and is not dose related, but related to the rate of infusion. Drug labeling calls for intravenous amiodarone to be administered over 10 minutes. A new aqueous formulation of amiodarone (Amio-Aqueous) does not contain vasoactive excipients and may be administered safely by rapid administration without hypotension. This hypothesis was tested using combined data of 4 clinical trials; each assessed the development of hypotension prospectively. Hypotension was defined as a 25% decrease in systolic blood pressure (BP), with the development of a systolic BP of <90 mm Hg or a systolic BP that decreased to <80 mm Hg. In all, 358 Amio-Aqueous and 225 lidocaine boluses were administered to 278 patients; 246 had ventricular tachycardia (VT) during drug administration. Hypotension developed in 11% of patients on Amio-Aqueous versus 19% on lidocaine (p = NS), all during VT; most resolved spontaneously with VT termination. With both drugs, hypotension persisted after VT termination in 1% of patients; the incidence of drug-related hypotension occurred in 2% of patients (1% had hypotension requiring treatment). The Amio-Aqueous was discontinued in 1% of patients, and lidocaine was discontinued in 2% of patients because of hypotension. We conclude that Amio-Aqueous is at least as safe as lidocaine in terms of causing hypotension when administered rapidly. This is a significant advantage over the standard amiodarone formulation, because Cordarone cannot be administered by rapid bolus owing to excipient-related hypotension.

Comparison of intracardiac echocardiography and transesophageal echocardiography for imaging of the right and left atrial appendages.

BACKGROUND: Transesophageal echocardiography (TEE) is the standard for diagnosis of atrial thrombi and is performed before ablation of atrial arrhythmias. Intracardiac echocardiography (ICE) is routinely used during these procedures and may provide an alternative imaging modality. OBJECTIVE: The purpose of this study was to compare TEE and ICE for right atrial appendage (RAA) and left atrial appendage (LAA) anatomy and thrombus. METHODS: This prospective blinded study enrolled 71 patients with atrial arrhythmias who presented for ablation. TEE and ICE were performed simultaneously to assess the RAA and LAA for thrombi, spontaneous echo contrast, and dimensions. ICE images were acquired sequentially from the right atrium, right ventricular outflow tract, and the pulmonary artery. RESULTS: Imaging of the RAA and LAA was achieved in all 71 patients using ICE but in only in 69 patients using TEE because of inability to intubate the esophagus. A total of 4 thrombi were diagnosed (3 LAA, 1 RAA). All were detected by ICE but only 1 by TEE. Diagnostic imaging of the LAA was achieved in 71 patients (100%) with ICE and in 62 patients (87.3%) with TEE (P < .002). Spontaneous echo contrast was more commonly diagnosed with ICE (P < .01). There was strong correlation between TEE and ICE for length (r = 0.71), width (r = 0.94), and area (r = 0.88) of the LAA. Image quality with ICE was highest from the pulmonary artery and lowest from the right atrium. CONCLUSION: ICE imaging is a viable alternative to TEE for visualization of the LAA and RAA during catheter ablation procedures.