Improved Resource Utilization With Similar Efficacy During Early Adoption of Cryoballoon Pulmonary Vein Isolation as Compared to Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

BACKGROUND: Cryoballoon pulmonary vein isolation (PVI) is an alternative to radiofrequency (RF) PVI for the treatment of paroxysmal atrial fibrillation (AF). Treatment effect, complication rates, and hospital length of stay are not well established with early use of cryoballoon PVI as compared to more experienced performance of RF PVI. PURPOSE: We reviewed the early experience of cryoballoon PVIs for paroxysmal AF performed by 3 operators at our institution compared to their most recent RF PVIs. All repeat procedures were excluded. Patients were assessed for recurrence of AF at 6 months after the procedure, including a 3-month blanking period. Complications, procedure time, and hospital length of stay were recorded. METHODS: Consecutive patients presenting to the ER with ECG-documented AF at an urban teaching hospital were treated according to a guideline-based care protocol, including a patient toolkit at ER discharge, and systematic referral to a rapid access AF clinic. Consenting patients received questionnaires on AF knowledge, patient satisfaction, and the AFEQT questionnaire at first visit and three-month follow-up. RESULTS: Final analysis included 50 cryoballoon PVIs and 50 RF PVIs. There was no significant difference in baseline characteristics or percentage of patients wearing a home monitor (80% for cryoballoon vs 80% for RF). Symptomatic improvement was experienced by 96% of cryoballoon PVI as compared to 86% of RF PVI patients (p=0.08). Freedom from AF at 6 months was similar between the two groups (70% for cryoballoon and 70% for RF, p=1). Complications were seen in 6% of cryoballoon procedures as compared to 10% of RF procedures (p=0.46). Hospital length of stay was significantly shorter in the cryoballoon group (1.6 vs 3.4 nights, p=0.003). CONCLUSION: At the time of its adoption, cryoballoon PVI is associated with shorter procedure times and hospital length of stay as compared to RF PVI in experienced operators while maintaining similar efficacy outcomes and complication rates.

Single-photon emission computed tomographic-multidetector computed tomographic fusion image integration: a potential aid to left ventricular substrate ablation.

AIMS: To illustrate the feasibility of ventricular tachycardia (VT) ablation assisted by single photon emission computed tomography (SPECT)-multidetector (MDCT) computed tomography 'fusion' image guidance. METHODS AND RESULTS: A patient with ischaemic cardiomyopathy and recurrent VT underwent catheter ablation. Prior to the procedure, SPECT and MDCT had been obtained. A combined ('fusion') image was created, and this image was registered to the operative field using a commercial catheter navigation system. There was a close anatomic and electrophysiological correspondence between the left ventricular electroanatomic map obtained in the operating theatre and the fusion image. CONCLUSION: If accuracy of this technique can be confirmed, fusion image guidance may offer a significant value during catheter ablation of VT, including improved substrate detail and procedure abbreviation.

Impact of scar on SPECT assay of left ventricular contraction dyssynchrony.

PURPOSE: Many patients presently receiving cardiac resynchronization therapy (CRT) do not respond. A disproportionate number of nonresponders have ischemic cardiomyopathy, with significant left ventricular (LV) scar burden. Current selection criteria, such as electrocardiography or echocardiography, may not reliably portray the magnitude of CRT-remediable LV contraction dyssynchrony. Although phase analysis of gated single photon emission computed tomography (SPECT) image data is increasingly appreciated as a tool for quantifying dyssynchrony, its use in the setting of scar has not been adequately evaluated. METHODS: Consecutive patients with ischemic (ICM, n = 50) or nonischemic (NICM, n = 39) cardiomyopathy underwent SPECT imaging prior to receiving CRT. In each patient, phase analysis of the raw images was performed to yield a phase standard deviation (PSD), an index which varies directly with the magnitude of dyssynchrony. ICM patient image data were also reanalyzed after scarred segments were stripped away. RESULTS: Raw image analysis demonstrated that PSD was significantly larger among ICM (57 ± 17°) than NICM (35 ± 13°, p < 0.001) patients. Among ICM patients, PSD after stripping of scarred segments was significantly decreased (40 ± 13°, p < 0.001). Signals emanating from scarred segments were of low amplitude and presented a random pattern, suggestive of noise rather than indicating contraction. CONCLUSION: PSD values may be spuriously increased by scar. These findings may be important when using SPECT in selecting ischemic cardiomyopathy patients for CRT.

Deterioration of left ventricular ejection fraction and contraction synchrony during right ventricular pacing in patients with left bundle branch block.

BACKGROUND: Electrocardiographic left bundle branch block (LBBB) may be intrinsic, due to ventricular conduction system disease, or induced by right ventricular pacing. Prior reports clearly delineate the derogatory impact of LBBB on left ventricular (LV) mechanical synchrony and global function, and suggest that the intrinsic and induced varieties are equivalent. This study sought to determine the difference in LV synchrony and global function between intrinsic LBBB and right ventricular apical pacing induced LBBB. METHODS: Ten patients with heart failure, diminished ejection fraction (EF) (33 ± 11%), intrinsic LBBB and an implanted cardiac pacing device were studied. In each patient, separate gated SPECT acquisitions were performed during intrinsic ventricular activation (atrial pacing) and during induced LBBB (atrial and right ventricular pacing). During each condition, LVEF, contraction synchrony (phase standard deviation, PSD), and spatial pattern of activation were measured. RESULTS: Compared to intrinsic, induced LBBB was associated with decreased EF (30 ± 11% vs 33 ± 11%, P = .007), contraction synchrony (PSD 49.7 ± 23.2° vs 41.6 ± 19.8, P = .02), and a disparate spatial pattern of activation. CONCLUSIONS: Induced LBBB is associated with significantly worse global and regional LV mechanical function than intrinsic LBBB.

Further deterioration of LV ejection fraction and mechanical synchrony during RV apical pacing in patients with heart failure and LBBB.

Electrocardiographic left bundle branch block (LBBB) may be due to intrinsic disease of the left bundle branch or induced by right ventricular apical (RVA) pacing. Prior reports clearly delineate the derogatory impact of LBBB on left ventricular (LV) mechanical function but suggest equivalent impact between varieties. We hypothesized that their effects were disparate and performed a within-patient comparison to test this notion. Patients (n = 20) with heart failure, intrinsic LBBB, and an implanted pacing device with right atrial and RVA leads were studied. Each patient underwent transthoracic three-dimensional speckle-tracking echocardiography during atrial pacing (intrinsic LBBB) and short atrioventricular delay atrial-RVA pacing, and these studies were compared. Relative to intrinsic LBBB, RVA pacing-induced LBBB produced greater intra-LV and interventricular dyssynchrony, a deterioration in LV function, and a shift in the site of latest activation. In patients with heart failure and LBBB, acute RVA pacing induces greater mechanical dyssynchrony and further impairs LV function.

On the importance of image gating for the assay of left ventricular mechanical dyssynchrony using SPECT.

UNLABELLED: The potential of SPECT for quantifying left ventricular mechanical dyssynchrony is increasingly appreciated. We sought to examine the incidence and impact of image gating errors on this quantification and to test a possible solution for affected studies. METHODS: First, to establish whether and how gating error alone could affect the measurement of dyssynchrony, we performed a prospective study in which patients with pacemakers were studied twice: during normal rhythm without gating error and with gating error caused by pacemaker-induced dysrhythmia. Second, to understand the pattern and magnitude of gating error during our typical imaging practice, we retrospectively examined studies from a separate cohort of 64 patients who were referred for dyssynchrony evaluation. Third, to understand whether studies with gating error could be repaired for the purpose of quantifying dyssynchrony, we tested a correction algorithm on the pacemaker-induced dysrhythmia image set to see whether it repaired this set so as to approximate the patients' normal rhythm image data. We subsequently applied this algorithm to the 64-patient cohort. RESULTS: Pacemaker-induced gating error caused a spurious decrease in dyssynchrony magnitude. Among the 64-patient cohort, similar gating errors were common, and an inverse exponential relationship between gating-error magnitude and dyssynchrony magnitude was observed. The correction algorithm accurately repaired the pacemaker-induced dysrhythmia image set; when it was applied to the 64-patient cohort, the magnitude of the postcorrection increase in dyssynchrony magnitude was proportional to the magnitude of the gating error. CONCLUSION: Gating errors cause a spurious reduction in SPECT assay of dyssynchrony magnitude. In our standard imaging practice, gating errors were common. Post hoc correction appears to be feasible.

A prospective pilot study to evaluate the relationship between acute change in left ventricular synchrony after cardiac resynchronization therapy and patient outcome using a single-injection gated SPECT protocol.

BACKGROUND: There are ongoing efforts to optimize patient selection criteria for cardiac resynchronization therapy (CRT). In this regard, the relationship between acute change in left ventricular synchrony (LV) after CRT and patient outcome remains undefined. METHODS AND RESULTS: A novel protocol was designed to evaluate acute change in left LV synchrony after CRT using phase analysis of standard gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging with a single injection of radiotracer and prospectively applied to 44 patients undergoing CRT. Immediately after CRT, 18 (41%), 11 (25%), and 15 (34%) patients had an improvement, no change, or a worsening in LV synchrony. An algorithm incorporating the presence of baseline dyssynchrony, myocardial scar burden, and lead concordance predicted acute improvement or no change in LV synchrony with 72% sensitivity, 93% specificity, 96% positive predictive value, and 64% negative predictive value and had 96% negative predictive value for acute deterioration in synchrony. Over a follow-up period of 9.6 ± 6.8 months, patients who had an acute deterioration in synchrony after CRT had a higher composite event rate of death, heart failure hospitalizations, appropriate defibrillator discharges, and CRT device deactivation for worsening heart failure symptoms, compared with patients who had an improvement or no change [hazard ratio, 4.6 (1.3 to 16.0); log rank test; P=0.003]. CONCLUSIONS: In this single-center pilot study, phase analysis of gated SPECT was successfully used to predict acute change in LV synchrony and patient outcome after CRT.

Newer applications of nuclear cardiology in systolic heart failure: detecting coronary artery disease and guiding device therapy.

Radionuclide-based imaging techniques can be applied to the heart failure population to derive clinically useful information. This review discusses the specific role of myocardial perfusion imaging for determining heart failure etiology, and the potential application of radionuclide-based imaging techniques for the optimal selection of patients with heart failure for device therapy.

Voltage-gated sodium channel blockers as cytostatic inhibitors of the androgen-independent prostate cancer cell line PC-3.

The recent discovery of sodium (Na(+)) channel expression in human prostate cancer (PCa) cells led us to investigate the potential use of neuronal Na(+) channel blockers as inhibitors of PCa cells. Our initial studies discovered two classes of Na(+) channel blockers that were effective inhibitors of PCa cell proliferation. Both hydroxyamides (compounds 1 and 4) and a hydantoin (compound 5) were shown to inhibit the androgen-independent PCa cell line PC-3 in vitro. Electrophysiology showed that all compounds functionally block brain type II voltage-gated Na(+) channels (Nav1.2) expressed in Xenopus laevis oocytes. Long-term growth assays in androgen-independent PC-3 cells showed remarkable inhibition of cell growth, with cells growing to a maximum of 30% of controls with analogue 1. Further, our analogues demonstrated only marginal impact on cell viability over the same treatment interval.