Four-year follow-up of outcomes of the hybrid epicardial-endocardial ablation: A single-center experience.

BACKGROUND: The CONVERGE trial demonstrated that hybrid epicardial and endocardial ablation was more effective than catheter ablation for the treatment of persistent atrial fibrillation (AF) at 1 year. Long-term real-world outcome data are scarce. OBJECTIVE: We described a single-center experience by evaluating the long-term effectiveness and safety of hybrid epicardial-endocardial ablation. METHODS: This is a retrospective single-center study. Patients were followed up to 4 years. The primary end point was the rate of AF recurrence up to 4 years postablation. Secondary end points included reduction in antiarrhythmic therapy use, the effect of the ligament of Marshall removal, epicardial posterior wall, 3-dimensional mapping during epicardial ablation, and left atrial appendage exclusion as adjunct intraoperative interventions for AF recurrence. RESULTS: Of the 170 patients, 86.5% had persistent AF and 13.5% had long-standing persistent AF. AF-free survival was 87.6% at 1 year, 76.9% at 2 years, 70.4% at 3 years, and 59.3% at 4 years. Antiarrhythmic drug use was 87.6% at baseline and reduced to 21%, 20.6%, 18%, and 14.1% at year 1, 2, 3, and 4, respectively (P < .01 for all). Three-dimensional epicardial mapping showed a significant reduction in combined recurrence from 42% to 25% over 4 years of follow-up (P = .023). Ligament of Marshall and left atrial appendage exclusion showed numerical reduction in AF recurrence from 35% to 26% (P = .49) and from 44% to 30% (P = .07). CONCLUSION: The hybrid convergent procedure reduces AF recurrence and the need for antiarrhythmic drugs and, while maintaining a good safety profile, for the treatment of persistent and long-standing persistent AF.

Neurogenic cardiac outcome in patients after acute ischemic stroke: The brain and heart connection.

BACKGROUND: Neurogenic cardiac impairment can occur after acute ischemic stroke (AIS), but the mapping of the neuroanatomic correlation of stroke-related myocardial injury remains uncertain. This study aims to identify the association between cardiac outcomes and middle cerebral artery (MCA) ischemic stroke, with or without insular cortex involvement, as well as the impact of new-onset atrial fibrillation (AF) after AIS on recurrent stroke. METHODS: Serial measurements of high sensitivity troponin T (TnT), brain natriuretic peptide (BNP), electrocardiography (ECG), echocardiogram, and cardiac monitoring were performed on 415 patients with imaging confirmed MCA stroke, with or without insular involvement. Patients with renal failure, recent cardiovascular events, or congestive heart failure were excluded. RESULTS: One hundred fifteen patients (28%) had left MCA infarcts with insular involvement, 122 (29%) had right MCA infarcts involving insular cortex, and 178 (43%) had no insular involvement. Patients with left MCA stroke with insular involvement tended to exhibit higher BNP and TnI, and transient cardiac dysfunction, which mimicked Takotsubo cardiomyopathy in 10 patients with left ventricular ejection fraction (LVEF) of 20-40%. Incidence of new-onset AF was higher in right MCA stroke involving insula (39%) than left MCA involving insula (4%). Nine out of fifty-three patients with new-onset AF were not on anticoagulant therapy due to various reasons; none of them experienced recurrent AF or stroke during up to a 3-year follow-up period. Statistically significant correlations between BNP or TnT elevation and left insular infarcts, as well as the incidence of AF and right insular infarcts, were revealed using linear regression analysis. CONCLUSIONS: The present study demonstrated that acute left MCA stroke with insular involvement could cause transient cardiac dysfunction and elevated cardiac enzymes without persistent negative outcomes in the setting of health baseline cardiac condition. The incidence of new-onset AF was significantly higher in patients with right MCA stroke involving the insula. There was no increased risk of recurrent ischemic stroke in nine patients with newly developed AF who were not on anticoagulant therapy, which indicated a need for further research on presumed neurogenic AF and its management.

Optimizing Care of Patients With Right Bundle Branch Block Undergoing Transcatheter Aortic Valve Replacement.

OBJECTIVES: To evaluate the use of temporary-permanent pacemaker (TPP) in patients with right bundle branch block (RBBB) undergoing transcatheter aortic valve replacement (TAVR). We also sought to identify key predictors of permanent pacemaker (PPM) within 30 days of TAVR in this population. BACKGROUND: RBBB is a well-recognized risk factor for PPM post TAVR. TPP provides stable transient pacing and reduces the need for critical care beds. METHODS: This is a retrospective chart review of 371 patients who underwent TAVR at our institution. All patients with pre-existing RBBB had TPP placed prior to TAVR (n = 37). The primary outcome was the need for critical care beds. Multivariate logistic regression analysis was performed to identify predictors of PPM within 30 days of TAVR. RESULTS: 67 patients required PPM within 30 days of TAVR, and 56 implanted before discharge. 51% (19 out of 37) of TPP group required PPM before discharge compared to 11% (37 out of 334) of No TPP (p < 0.001), yet TPP group spent significantly fewer hours in a critical care bed (19 vs 28 h, p = 0.01). Length of membranous septum (LMS) <8.49 mm was the strongest independent predictor of PPM within 30 days of TAVR (RAUC of 0.80, Sensitivity 0.7 and Specificity 0.8) and 98% of patients with LMS < 7 mm required PPM within 30 days. CONCLUSION: TPP-TAVR is a well-defined multidisciplinary protocol that reduces the need for critical care beds in patients with pre-existing RBBB referred for TAVR. Additionally, LMS is the strongest predictor of PPM implantation in this population. CONDENSED ABSTRACT (100 WORDS): This study evaluated the use of temporary-permanent pacemakers (TPP) in patients with right bundle branch block (RBBB) undergoing transcatheter aortic valve replacement (TAVR). TPP-TAVR provided stable pacing allowing for early mobilization and reduced the need for critical care beds. Multivariate logistic regression analysis identified length of membranous septum (LMS) <8.49 mm in patients with RBBB as the strongest independent predictor of PPM need within 30 days of TAVR. 98% of patients with RBBB and LMS < 7 mm required PPM at 30 days regardless of other characteristics including valve type and size.

Accuracy of pulsatile photoplethysmography applications or handheld devices vs. 12-lead ECG for atrial fibrillation screening: a systematic review and meta-analysis.

BACKGROUND: The relative accuracy of pulsatile photoplethysmography applications (PPG) or handheld (HH) devices compared with the gold standard 12-lead electrocardiogram (ECG) for the diagnosis of atrial fibrillation is unknown. METHODS: Digital databases were searched to identify relevant articles. Raw data were pooled using a bivariate model to calculate diagnostic accuracy measures and estimate Hierarchical Summary Receiver Operating Characteristic (HSROC). RESULTS: A total of 10 articles comprising 4296 patients (mean age 68.9 years, with 56% males) were included in the analysis. Compared with EKG, the pooled sensitivity of PPG and HH devices in AF detection was 0.93 (95% CI 0.87-0.96; p < 0.05) and 0.87 (95% CI. 0.74-0.94; p < 0.05), respectively. The pooled specificity of PPG and HH devices in AF detection was 0.91 (95% CI 0.88-0.94; p < 0.05) and 0.96 (95% CI 0.90-0.98; p < 0.05), respectively. The diagnostic odds ratio was 129 and 144 for PPG and HH devices, respectively. Fagan's nomogram showed the probability of a patient having AF and normal rhythm on PPG or HH devices was 2-3%, while the post-test probability of having AF with an irregular R-R interval on PPG or HH devices was 73% and 82%, respectively. The scatter plot of positive and negative likelihood ratio showed high confirmation of AF and reliability of exclusion of absence of irregular R-R intervals (positive likelihood ratio > 10, and negative likelihood ratio < 0.1) on HH devices while PPG was used as confirmation only. CONCLUSIONS: The PPG or HH devices can serve as a reliable alternative for the detection of AF.

A cost comparison of atrial fibrillation monitoring strategies after embolic stroke of undetermined source.

Background: Detection of atrial fibrillation (AF) in patients with embolic stroke of undetermined source (ESUS) is challenging due to its paroxysmal nature. We sought to assess AF detection with an insertable cardiac monitor (ICM) and to perform cost analysis for various AF monitoring strategies post-ESUS We applied this cost analysis modeling to recently published Stroke AF and Per Diem trials. Methods: Retrospective chart review was performed in consecutive hospitalized patients with ESUS who had ICM placed prior to discharge. Utilizing rate of ICM-detected AF and Medicare average payments, we modeled 30-day per-patient diagnostic costs of Immediate ICM insertion prior to discharge versus using a wearable monitor followed by ICM in patients with ESUS, from Medicare and patient out-of-pocket perspectives. Similar modeling strategy and cost analysis was applied to the Stroke AF and Per Diem trials. Results: In 192 ESUS patients, AF detection increased with length of monitoring: 7.3 % at 14 days, 9.4 % at 30 days, and 17.2 % after a median ~ 6 months (189 days). Cost modeling predicted that immediate ICM leads to $3683-$4070 lower Medicare payments per-patient and $1425-$1503 lower patient out-of-pocket costs compared to Wearable-to-ICM strategies. Using similar modeling in the PER DIEM and STROKE AF trials, the additive costs of the 30-day ELR to ICM strategy ranged from $3786-$3946 from a payer perspective and $1472-$1503 from a patient out-of-pocket perspective. Conclusions: Use of ICM immediately after ESUS is cost-saving compared to Wearable-to-ICM strategies, due to the cost and low diagnostic yield of short-term wearable cardiac monitoring.

Same-day discharge after cryoballoon ablation of atrial fibrillation: A multicenter experience.

BACKGROUND: It is common practice to observe patients during an overnight stay (ONS) following a catheter ablation procedure for the treatment of atrial fibrillation (AF). OBJECTIVES: To investigate the safety and economic impact of a same-day discharge (SDD) protocol after cryoballoon ablation for treatment of AF in high-volume, geographically diverse US hospitals. METHODS: We retrospectively reviewed 2374 consecutive patients (1119 SDD and 1180 ONS) who underwent cryoballoon ablation for AF at three US centers. Baseline characteristics, acute procedure-related complications, and longer-term evaluations of safety were recorded during routine clinical follow-up. The mean cost of an ONS was used in a one-way sensitivity analysis to evaluate yearly cost savings as a function of the percentage of SDD cases per year. RESULTS: The SDD and ONS cohorts were predominately male (69% vs. 67%; p = .3), but SDD patients were younger (64 ± 11 vs. 66 ± 10; p < .0001) with lower body mass index (30 ± 6 vs. 31 ± 61; p < .0001) and CHA2 DS2 -VASc scores (1.4 ± 1.0 vs. 2.2 ± 1.4; p < .0002). There was no difference between SDD and ONS in the 30-day total complication rate (n = 15 [1.26%] versus n = 24 [2.03%]; p = .136, respectively). The most common complication was hematoma in both the SDD (n = 8; 0.67%) and ONS (n = 11; 0.93%) cohorts. Sensitivity analysis demonstrated that when 50% of every 100 patients treated were discharged the same day, hospital cost savings ranged from $45 825 to $83 813 per year across US hospitals. CONCLUSIONS: SDD following cryoballoon ablation for AF appears to be safe and is associated with cost savings across different US hospitals.

Left Atrial Volume Index Predicts Arrhythmia-Free Survival in Patients with Persistent Atrial Fibrillation Undergoing Cryoballoon Ablation.

BACKGROUND: Pulmonary vein isolation (PVI) using cryoballoon ablation (PVI-C) is increasingly performed as a first-line strategy for the treatment of patients with persistent atrial fibrillation (PersAF); however, follow-up data and predictors of procedural success are lacking. OBJECTIVE: To study the efficacy of PVI-C in patients with PersAF, focusing on predictors of procedural success. METHODS: By retrospective review, 148 consecutive patients with PersAF who underwent PVI-C were analyzed. The impact of several variables on outcome was evaluated in univariate and multivariate analyses and Cox proportional hazards regression models. RESULTS: After a mean follow-up of 19.2±10.9 months, 75 (50.7%) patients remained arrhythmia-free without the need for antiarrhythmic drug therapy. Patients with a normal left atrial volume index (LAVI) achieved a 71.0% arrhythmia-free survival. LAVI was the most powerful predictor of procedural success. CONCLUSIONS: Arrhythmia-free survival after PVI-C in select patients with PersAF are promising. Moreover, LAVI is a valuable measurement to help guide ablation strategy and predict outcome when using cryoballoon ablation.

Cardiac amyloidosis: The great masquerader.

Cardiac amyloidosis is an elusive condition that is notorious for mimicking various cardiovascular conditions that present with left ventricular hypertrophy (LVH). The hypertrophy in amyloidosis is typically diffuse; however, rare reports of echocardiographic resemblances with hypertrophic cardiomyopathy (HCM) exist, such as asymmetric septal hypertrophy and left ventricular outflow tract obstruction. Cardiac MRI can help differentiate amyloidosis from hypertrophic cardiomyopathy in unclear situations. This differentiation from HCM and other forms of cardiomyopathy has important treatment implications. Here we present the case of a 76-year-old man with cardiomyopathy who had echocardiographic features of asymmetric hypertrophic cardiomyopathy but was correctly diagnosed with amyloidosis with the help of cardiac MRI and ECG.

Hypertrophic cardiomyopathy with a large apical ventricular aneurysm and mural thrombus.

Hypertrophic cardiomyopathy (HCM) is characterized by increased left ventricular wall thickness in the absence of any other identifiable cause of thickness. It predisposes the patient to increased risk of sudden cardiac death (SCD) due to fatal arrhythmias. Approximately 2% of the HCM patients have left ventricular apical aneurysm. CMR imaging is better in identifying this apical aneurysm as compared to echocardiogram. This apical aneurysm, which can be akinetic or dyskinetic, increases the risk of disease-related adverse events as compared to general HCM. These adverse disease-related events include SCD, thromboembolism, and symptoms of heart failure. We report a rare case of hypertrophic cardiomyopathy in association with Williams-Beuren Syndrome. On CMR imaging, patient was found to have a large apical aneurysm and mid-ventricular obstruction with underlying thrombus. He was started on oral anticoagulation, and ICD was recommended.

Safety of anticoagulation with uninterrupted warfarin vs. interrupted dabigatran in patients requiring an implantable cardiac device.

BACKGROUND: The optimal strategy of peri-procedural anticoagulation in patients undergoing permanent cardiac device implantation is controversial. Our objective was to compare the major bleeding and thromboembolic complications in patients managed with uninterrupted warfarin (UW) vs. interrupted dabigatran (ID) during permanent pacemaker (PPM) or implantable cardioverter defibrillators (ICD) implantation. METHODS: A retrospective cohort study of all eligible patients from July 2011 through January 2012 was performed. UW was defined as patients who had maintained a therapeutic international normalized ratio (INR) on the day of the procedure. ID was defined as stopping dabigatran ≥12 hours prior to the procedure and then resuming after implantation. Major bleeding events included hemothorax, hemopericardium, intracranial hemorrhage, gastrointestinal bleed, epistaxis, or pocket hematoma requiring surgical intervention. Thromboembolic complications included stroke, transient ischemic attack, deep venous thrombosis, pulmonary embolism, or arterial embolism. RESULTS: Of the 133 patients (73.4±11.0 years; 91 males) in the study, 86 received UW and 47 received ID. One (1.2%) patient in the UW group sustained hemopericardium perioperatively and died. In comparison, the ID patients had no complications. As compared to the ID group, the UW group had a higher median CHADS2 score (2 vs. 3, P=0.04) and incidence of Grade 1 pocket hematoma (0% vs. 7%, P=0.09). Neither group developed any thromboembolic complications. CONCLUSIONS: Major bleeding rates were similar among UW and ID groups. Perioperative ID appears to be a safe anticoagulation strategy for patients undergoing PPM or ICD implantation.

Cardiac perforation and lead dislodgement after implantation of a MR-conditional pacing lead: a single-center experience.

OBJECTIVE: The purpose of our study was to determine if the rate of lead-related complications was increased with the Medtronic CapSureFix MRI™ SureScan™ 5086 MRI pacing lead (5086; Medtronic Inc., Minneapolis, MN, USA) compared to the previous generation of Medtronic CapSureFix Novus™ 5076 pacing lead (5076). BACKGROUND: The 5086 lead is a newly introduced active-fixation pacemaker lead designed to be used conditionally in a magnetic resonance (MR) scanner. This lead has specific design changes compared to the previous generation of 5076 pacing leads. METHODS: This study was a retrospective case control study of 65 consecutive patients implanted with two 5086 leads compared to 92 consecutive control patients implanted with two 5076 leads over a 14-month period at a high-volume tertiary care hospital. RESULTS: Pericarditis, pericardial effusion, cardiac tamponade, or death within 30 days of implant were seen in eight patients from the 5086 cohort and two from the 5076 cohort (odds ratio 6.3, 95% confidence interval 1.3-30.8, P = 0.02). Lead dislodgement occurred in four of the 5086 patients and in none of the 5076 patients (P < 0.03). CONCLUSIONS: In a high-volume center, the incidence of pericarditis, cardiac perforation, tamponade, death, and lead dislodgement was significantly higher with the MR-conditional Medtronic 5086 lead when compared to the previous generation Medtronic 5076 lead.

Attitudes of Implanting Physicians about Cardiac Rhythm Management Devices and Their Features.

Modern cardiac rhythm management systems have become increasingly complex. The decision on which specific system to implant in a given patient often rests with the implanting physician. We conducted a multiple-choice survey to assess the opinions and preferences of cardiologists and electrophysiologists who implant and follow cardiac rhythm management systems. Reliability and battery longevity were viewed as the most important characteristics in device selection. Patient characteristics which most affected device choice were pacing indication and life expectancy. Remote technology was used in 47% of pacemaker patients, 64% of ICD patients, and 65% of CRT-D patients, with wireless (radiofrequency) remote patient monitoring associated with higher patient compliance rates (74% versus 64%, resp.). Wireless remote patient management with alerts for atrial tachyarrhythmias was felt to be important by 76% of respondents. When choosing an MR-conditional device, physicians deemed patients with prior orthopedic problems, a history of cancer, or neurological disorders to be more likely to require a future MRI. Device longevity and reliability remain the most important factors which influence device selection. Wireless remote patient monitoring with alerts is considered increasingly important when choosing a specific cardiac rhythm management system to implant.

Syncope and recurrent ventricular tachycardia with a newly identified desmosomal gene mutation.

Ventricular arrhythmias in young people most commonly occur due to the presence of hypertrophic cardiomyopathy, long QT syndrome or Wolff-Parkinson-White syndrome. We present a case in which the patient had exercise induced syncopal spells and was found to have ventricular tachycardia (VT) during both exercise stress testing and an electrophysiology study. Further genetic studies showed a previously unseen desmosomal gene mutation confirming the presence of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC).

Simultaneous use of implantable cardioverter-defibrillators and left ventricular assist devices in patients with severe heart failure.

More patients who are receiving therapy with a left ventricular assist device (LVAD) also have an implantable cardioverter-defibrillator (ICD). The aim of the present study was to describe the outcomes and device interactions of simultaneous therapy with an ICD and a LVAD. We evaluated 76 patients with class IV heart failure (age 52 + or - 12 years, left ventricular ejection fraction 0.13 + or - 0.05%, 88% men, 61% nonischemic cardiomyopathy) with both an ICD and a LVAD. The median follow-up with both devices was 156 days. A LVAD with a pulsatile and continuous flow pump was used in 53 (70%) and 23 (30%) patients, respectively. Of the 76 patients, 12 (16%) received a total of 54 ICD therapies. Of the ICD therapies, 88% were appropriate. Of the 76 patients, 55 (72%) underwent heart transplantation a median of 146 days after LVAD implantation. Twelve patients (16%) died during simultaneous ICD and LVAD therapy. Interactions between the LVAD and ICD occurred in 2 patients (2.7%) with continuous flow pumps (HeartMate II). In both cases, telemetry failure occurred after LVAD implantation with 2 different models of ICDs from the same manufacturer. No ICD therapies occurred because of device-related interactions. In conclusion, simultaneous ICD and LVAD therapy in patients with severe congestive heart failure is safe and clinically feasible. Interactions between the devices are uncommon and appear limited to specific models of ICDs.

A randomized assessment of the incremental role of ablation of complex fractionated atrial electrograms after antral pulmonary vein isolation for long-lasting persistent atrial fibrillation.

OBJECTIVES: This study sought to determine whether ablation of complex fractionated atrial electrograms (CFAEs) after antral pulmonary vein isolation (APVI) further improves the clinical outcome of APVI in patients with long-lasting persistent atrial fibrillation (AF). BACKGROUND: Ablation of CFAEs has been reported to eliminate persistent AF. However, residual pulmonary vein arrhythmogenicity is a common mechanism of recurrence. METHODS: In this randomized study, 119 consecutive patients (mean age 60 +/- 9 years) with long-lasting persistent AF underwent APVI with an irrigated-tip radiofrequency ablation catheter. Antral pulmonary vein isolation resulted in termination of AF in 19 of 119 patients (Group A, 16%). The remaining 100 patients who still were in AF were randomized to no further ablation and underwent cardioversion (Group B, n = 50) or to ablation of CFAEs in the left atrium or coronary sinus for up to 2 additional hours of procedure duration (Group C, n = 50). RESULTS: Atrial fibrillation terminated during ablation of CFAEs in 9 of 50 patients (18%) in Group C. At 10 +/- 3 months after a single ablation procedure, 18 of 50 (36%) in Group B and 17 of 50 (34%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.84). In Group A, 15 of 19 patients (79%) were in sinus rhythm. A repeat ablation procedure was performed in 34 of 100 randomized patients (for AF in 30 and atrial flutter in 4). At 9 +/- 4 months after the final procedure, 34 of 50 (68%) in Group B and 30 of 50 (60%) in Group C were in sinus rhythm without antiarrhythmic drugs (p = 0.40). CONCLUSIONS: Up to 2 h of additional ablation of CFAEs after APVI does not appear to improve clinical outcomes in patients with long-lasting persistent AF.

Relationship between the spectral characteristics of atrial fibrillation and atrial tachycardias that occur after catheter ablation of atrial fibrillation.

BACKGROUND: During catheter ablation of complex fractionated atrial electrograms, persistent atrial fibrillation (AF) may convert to an atrial tachycardia (AT). OBJECTIVE: The purpose of this study was to investigate the possible mechanisms of AT by examining the spectral and electrophysiologic characteristics of AF and ATs that occur after catheter ablation of AF. METHODS: The subjects of this study were 33 consecutive patients with persistent AF who had conversion of AF to AT during ablation of AF (group I) and 20 consecutive patients who underwent ablation of persistent AT that developed more than 1 month after AF ablation (group II). Spectral analysis of the coronary sinus (CS) electrograms and lead V(1) was performed during AF at baseline, before conversion, and during AT. The spatial relationship between the AT mechanism and ablation sites was examined. RESULTS: A spectral component with a frequency that matched the frequency of AT was present in the baseline periodogram of AF more often in group I (52%) than in group II (20%, P = .02). Ablation resulted in a decrease in the dominant frequency of AF but not in the frequency of the spectral component that matched the AT. There was a significant direct relationship between the baseline dominant frequency of AF and the frequency of AT in the CS in group I (r = 0.76, P <.0001) but not in group II (r = 0.38, P = .09). ATs were macroreentrant in 64% and 60% of patients in groups I and II, respectively (P = .8). The AT site was more likely to be distant (>1 cm) from AF ablation sites in group I (70%) than in group II (35%, P = .007). CONCLUSION: The findings of this study suggest that ATs observed during ablation of AF often may be drivers of AF that become manifest after elimination of higher-frequency sources and fibrillatory conduction.

High-output pacing in mapping of postinfarction ventricular tachycardia.

BACKGROUND: Pace mapping is used to identify critical areas for postinfarction ventricular tachycardia (VT). Unexcitable scar during pacing with standard output can identify borders of the reentry circuit. Unexcitable scar is not thought to contain surviving muscle fibers critical to the circuit. Due to current-to-load mismatch or a deep seated isthmus, higher power might be required in order to obtain capture. OBJECTIVE: The purpose of this study was to evaluate the value of high-output pacing in patients with postinfarction VT. METHODS: In a consecutive series of 18 patients (15 men, age 62 +/- 9, EF 0.29 +/- 0.15) with postinfarction VT, a voltage map was obtained and bipolar pace mapping was performed in areas with low voltage (<1.5 mV) at an output of 10 mA and 2 ms pulse width (PW). High-output capture was defined as capture that failed at these settings but succeeded at higher pacing output. The pacing output was increased to 20 mA at 2 ms, and the PW was increased to 10 ms as required to achieve capture. RESULTS: Seventy-seven VTs were induced. Thirty-nine isthmus sites were identified. Focal areas with high-output capture were observed in 12/18 patients (output: 20 mA; mean PW: 7.3 +/- 3.5 ms). In 9/18 patients, this area was critical for the reentry circuit of 10 clinical VTs (23% of isthmus sites). In one third of patients, isthmus sites were identified only by high-output pacing. CONCLUSION: High-output pacing can be helpful in identifying critical areas of postinfarction VT that otherwise may be missed.

Complex electrograms within the coronary sinus: time- and frequency-domain characteristics, effects of antral pulmonary vein isolation, and relationship to clinical outcome in patients with paroxysmal and persistent atrial fibrillation.

BACKGROUND: The mechanistic and clinical significance of complex fractionated atrial electrograms (CFAE) in the coronary sinus (CS) has been unclear. METHODS AND RESULTS: Antral pulmonary vein isolation (APVI) was performed in 77 patients with paroxysmal (32) or persistent AF (45). CS electrograms recorded for 60 seconds before and after APVI were analyzed in the time- and frequency-domains. Dominant frequency (DF), complexity index (CI: change in polarity of depolarization), and fractionation index (FI: change in direction of depolarization slope) were determined. Before APVI, there was no difference in DF, CI, or FI between paroxysmal and persistent AF. APVI resulted in a significant decrease in DF, CI, and FI in all patients. Baseline CI (43 +/- 13/s vs 54 +/- 14/s, P = 0.03) and FI (64 +/- 23/s vs 87 +/- 30/s, P = 0.02) were lower in patients with paroxysmal AF who had AF terminated by ablation than who did not. At 10 +/- 2 months, 69% of patients with paroxysmal AF and 49% of patients with persistent AF were free from AF after single ablation. Baseline CI was higher among patients with paroxysmal AF who had AF after APVI (56 +/- 20/s vs 44 +/- 10/s, P = 0.03). In patients with persistent AF, there was a larger decrease in DF after APVI among patients who remained free from AF (13 +/- 11% vs 7 +/- 9%, P < 0.05). CONCLUSIONS: Complexity of CS electrograms may reflect drivers of AF that perpetuate paroxysmal AF after APVI. In persistent AF, the extent to which APVI decreases DF in the CS correlates with efficacy, suggesting that DF identifies patients who may require additional ablation beyond APVI.

Prevalence and characteristics of continuous electrical activity in patients with paroxysmal and persistent atrial fibrillation.

BACKGROUND: Complex fractionated atrial electrograms (CFAEs) may play a role in the genesis of atrial fibrillation (AF). One type of CFAE is continuous electrical activity (CEA). The prevalence and characteristics of CEA in patients with paroxysmal and persistent AF are unclear. METHODS AND RESULTS: In 44 patients (age = 59 +/- 8 years) with paroxysmal (25) or persistent (19) AF, bipolar electrograms were systematically recorded for > or =5 seconds at 24 left atrial (LA) sites, including 8 antral sites, and 2 sites within the coronary sinus (CS). CEA was defined as continuous depolarization for >1 second with no isoelectric interval. CEA was recorded at the LA septum (79%), antrum (66%), posterior (68%) and anterior walls (67%), roof (66%), base of the LA appendage (61%), inferior wall (61%), posterior mitral annulus (48%), CS (41%), and in the LA appendage (14%). Antral CEA was equally prevalent in patients with paroxysmal (63%) and persistent AF (70%, P = 0.12). In patients with paroxysmal AF, the prevalence of CEA was similar among antral and nonantral LA sites, except for the LA appendage. However, in patients with persistent AF, CEA was more prevalent at the nonantral (80%) than antral sites (70%, P = 0.03). CEA at nonantral sites except the CS was more prevalent in persistent than in paroxysmal AF (80% vs 57%, P < 0.001). The mean duration of intermittent episodes of CEA was longer in persistent than in paroxysmal AF (P < 0.001). CONCLUSIONS: The higher prevalence and duration of CEA at nonantral sites in persistent than in paroxysmal AF is consistent with a greater contribution of LA reentrant mechanisms in persistent AF. However, the high prevalence of CEA at nonantral sites in paroxysmal atrial fibrillation (PAF) suggests that CEA alone is a nonspecific marker of appropriate target sites for ablation of AF. The characteristics of CEA that most accurately identify drivers of AF remain to be determined.