P4-53

Poster 4 Uwe K. H. Wiegand, MBBS, Frank Bode, MD and Hendrik Bonnemeier, MD. University Luebeck, Luebeck, Germany. Background: Early recurrence of atrial fibrillation (AF) after electrical cardioversion (CV) is attributed to alterations of cardiac autonomic activity. The biphasic waveform has been shown to be superior in efficacy to the monophasic waveform in CV of AF. Whether biphasic CV has an impact on cardiac autonomic modulation after CV of AF is unclear. Methods: We investigated 171 consecutive patients (mean age 65.4 years, 70 % male, 80% structural heart disease) undergoing successful external electrical CV for AF. We performed biphasic CV (Bi) in 82 and monophasic CV (Mo) in 89 patients. The two groups did not differ regarding age, gender, body mass index, underlying cardiovascular disease, left atrial diameter, ejection fraction, mean duration of AF, and drug therapy. Herat rate variability (HRV) was analysed from 24-hour Holter ECG recordings, started directly after CV. Results: Mean delivered total energy was significantly lower in the Bi group (Bi: 223 ⫾ 163 Ws, Mo: 355 ⫾ 211 Ws; p⬍ 0.001). Mean RR-interval decreased within 5 hours after CV and consecutively increased again within the remaining hours, without significant differences between Bi and Mo groups. The time courses of time domain parameters of HRV revealed biphasic profiles with the lowest levels 6 hours after CV in both groups, however hourly values of HRV were significantly higher in the Bi group (p⬍ 0.05). Subgroup analysis within the biphasic group showed significantly higher time domain HRV values in patients’ cardioverted by energy level lower than 200 joule. Conclusion: Our data indicate that waveform and delivered energy significantly influence autonomic modulation of the sinus node after successful CV of AF. Bi CV prevents an early reduction of cardiac vagal modulation, which may have an antiarrhythmic effect by reducing early electrical remodeling after CV of AF.

P4-51 A NOVEL FIDING OF BI-ATRIAL VOLTAGE MAPPING: IMPAIRMENT OF RIGHT ATRIAL SUBSTRATE BY CHRONIC NICOTINE EXPOSURE IN PATIENTS WITH ATRIAL FIBRILLATION Ta-Chuan Tuan, MD, Ching-Tai Tai, MD, Yenn-Jiang Lin, MD, Shih-Lin Chang, MD, Wanwarang Wongcharoen, MD, Sheng-Hsiung Chang, MD and Shih-Ann Chen, MD. Taipei Veterans General Hospital, Taipei, Taiwan Republic of China. Introduction: Smoking is a major risk factor of cardiovascular disease. Previous study demonstrated that chronic nicotine exposure was related with atrial flutter. However, the impact of smoking on right and left atrial substrate is unknown. Methods: This study included 50 Patients (48⫾14 y/o, M/F⫽40/10) who received 4 pulmonary vein isolation for drug refractory, paroxysmal atrial fibrillation (AF). The substrate characteristics were indicated by peak-topeak bipolar voltage. The mean voltage of individual atrium was obtained by using NavX mapping system, and was compared between patients with and without previous smoking history. Dose-dependent effect by nicotine was evaluated by smoking intensity- duration, defined as pack per day, times by year. Results: The mean peak-to-peak bipolar voltage of RA (mapping sites⫽268⫾53 points) is lower in patients with previous history of smoking (intensity-duration⬎10) compared to without history of smoking

S235 (1.9⫾0.6 mV vs. 2.9⫾0.4 mV, respectively, P⬍0.05). Conversely, the mean peak-to-peak bipolar voltage of LA (mapping sites⫽279⫾66 points) was similar between the two groups (1.7⫾1.0 mV vs. 1.9⫾0.5 mV, P⫽0.8). Furthermore, the voltage reduction of RA was dependent on the smoking intensity-duration in patients with smoking (Pearson’s correlation, r⫽0.54, P⫽0.02). These heavy smoking patients were associated with sustained RA flutter. Conclusion: In patients with AF, the RA voltage was significantly reduced due to chronic nicotine exposure with a dose-dependent effect. The substrate change may perpetuate right atrial tachyarrhythmia. P4-52 RELATIONSHIP BETWEEN ELECTROGRAM FRACTIONATION AND ACTION POTENTIAL VARIABILITY IN ATRIAL FIBRILLATION Sanjiv M. Narayan, MD, PhD, David E. Krummen, MD, Pamela L. Karasik, MD and Michael R. Franz, MD, PhD. University of California and VA, San Diego Medical Center, San Diego, CA and VA Medical Center, Washington, DC. Background: Fractionated electrograms are increasingly used to guide AF ablation yet, since traditional bipoles cancel waveform shape, fractionation may reflect waveform variability, true fragmentation or artifact. We hypothesized that monophasic action potentials (MAPs) would show differing AF waveform variability in the presence and absence of bipolar fractionation. Methods and Results: In 28 patients with paroxysmal or persistent AF and left atrial diameter 44⫾8 mm, we recorded right atrial MAPs during AF for 2-5 minutes, and obtained bipolar electrograms by routine filtering (30-500 Hz) at the same site. In 49 recordings, we graded simultaneous MAP and bipolar waveforms as regular, variable or fractionated. Surprisingly, fractionation was over-estimated by bipolar electrograms (43%; fig A), and often reflected noise in MAPs (21%, fig B; p⫽0.005). Conversely, MAP variability or alternans were often regular in bipoles (fig. C). Thus, the presence or absence of bipolar fractionation poorly predicted waveform variability (fig. C). Furthermore, spectral dominant frequency (DF) of MAPs accurately estimated measured AF cycle length (CL, R⫽0.73, p⬍0.01), with 77 % of estimates within ⱕ 20 ms of measured CL; spectral accurates were inaccurate for bipolar DF (R⫽0.31; p⫽NS). Conversely, a novel autocorrelation method that estimates CL by successive Pearson correlation of MAPs better estimated MAP CL (R⫽0.92; p⬍0.001) with 89% of estimates ⱕ 20 ms from measured CL. Conclusions: AF organization and rate are better represented in MAPs, which portray waveform shape, than traditional bipolar recordings. This approach may better identify electrogram fragmentation and rate distributions for the accurate mapping of AF substrates.

P4-53 TIME COURSE OF ATRIAL ACTIVATION AND LA SIZE DURING THE INDUCTION OF AND RECOVERY FROM ATRIAL FIBRILLATION Andrew Mykytsey, MD, Alexandru Chicos, MD, Nimrod Lavi, MD, Khoi M. Le, MD and Boaz Avitall, MD, PhD. University of Illinois at Chicago, Chicago, IL and Advocate Illinois Masonic Medical Center, Chicago, IL. We hypothesized that prolongation of the atrial activation and LA dilatation correlates with induction and recovery from atrial fibrillation (AF). Methods: In 8 dogs AVN was ablated and the RV was paced at 80 b/m. AF was induced by rapid atrial pacing (RAP, 660 b/m) until sustained AF

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was documented by daily interrogation of the atrial electrograms and ECG. Atrial activation time as assessed by signal averaging of 200 P wave complexes (SAPW) in the X, Y and Z axis. P wave width measurements were made at baseline and at least X2 weekly while the RAP is off and the atria are in NSR. RAP continued until AF was sustained. Similarly LA area was assessed using TTE. Following 3 month of Spontaneous AF the atria was DCCV and SAPW and LA area were assessed at 1 day, 1, 2 weeks and 3 month. Results: AF was induced within 28⫾13 days of RAP, as shown in the Table significant SAPW and LA area increase were documented just prior to the initiation of sustained AF with similar incremental change of 30 and 31% respectively. In all the animals the LA area size continued to increase reaching 14.7⫾1 cm2 (p⬍0.001 vs. BL). SAPW recovered to BL within 24 hours following DCCV. However the LA area recovered significantly slower and yet to reach BL at 2 weeks post DCCV. After 3 month in NSR with both SAPW and LA area at BL re-induction of AF by RAP required 4⫾1 days to induce AF. Conclusions: 1. Chronic AF preceded by significant SAPW prolongation and LA enlargement of 30 and 31% as a result of the RAP. 2. Despite 3 month of spontaneous AF, SAPW recovers to the pre pacing and AF baseline values within 24 hours following DCCV. In contrast to the SAPW the LA area recovery is longer than 2 weeks. 3. The marked increase in atrial susceptibility to re-induction of AF is not associated with SAPW or LA size abnormalities. Post DCCV BL

Pre AF

1st day

1 week

2 weeks

SAPW 93.3 ⫾ 13 122 ⫾ 21* 104 ⫾ 18.5 82 ⫾ 12 84.3 ⫾ 16.5 LA Area 10.5 ⫾ 0.5 13.6 ⫾ 2.1* 14.3 ⫾ 0.8* 13.1 ⫾ 1.1* 12.1 ⫾ 1.8 SAPW- in msec. LA Area- cm2, AVG⫾ STD, BL⫽baseline, * p⬍0.01 vs. BL

P4-54 MODERATE PHYSICAL TRAINING IMPROVES VENTRICULAR RATE CONTROL IN PATIENTS WITH PERMANENT ATRIAL FIBRILLATION Jurgita Plisiene, MD, Alexander Blumberg, MD, Gudrun Haager, Christian Knackstedt, MD, Joachim Latsch, MD, Stefan Tuerk, MD, Hans-Georg Predel, MD and Patrick Schauerte, MD. University Hospital Aachen, Aachen, Germany and German Sport University Cologne, Cologne, Germany. Objective: Adequate ventricular rate (VR) control in patients with permanent atrial fibrillation (AF) is not easy to accomplish. Especially excess VR increases can often be observed during physical exertion thus limiting exercise capacity. In addition, chronic elevated mean VR may promote tachycardiomyopathy. We assessed whether regular moderate physical activity elevates the parasympathetic tone to the AV node and decreases the VR during permanent AF. Methods: In 10 patients (7m/3w, mean age 59⫾10) with permanent AF (duration 9.8⫾7.6 y) underwent moderate physical exercise adjusted to the individual patient‘s physical capability (60 min walking/jogging twice a week). To analyse VR control physical exercise tests and Holter ECG recordings were performed before and after 4 months. In addition, stepwise lactate tests and subjective exercise tolerance levels estimates via Borg scales were obtained. Results: After 4 months of training VR at rest significant decreased from 87⫾18 to 78⫾15 bpm (p⫽0.02). Likewise, the mean ventricular rate in 24 hours Holter ECGs decreased from 76⫾20 bpm to 67⫾12 bpm (p⫽0.05). At almost every exercise level a significant VR decrease was observed (Table). VR at maximal exercise level similarly decreased despite an increase of maximal exercise capacity after 4 months. Overall exercise capacity as estimated by repeated lactate measurements and by questionnaires also significantly improved.

Exercise (Watt)

0

25

40

55

70

85

100

max.

VR(bpm, baseline) VR(bpm,4 months) P

87 ⫾ 18 78 ⫾ 15 0.02

97 ⫾ 20 87 ⫾ 18 0.001

102 ⫾ 22 93 ⫾ 19 0.05

109 ⫾ 22 100 ⫾ 24 0.01

118 ⫾ 22 111 ⫾ 25 0.02

126 ⫾ 26 120 ⫾ 27 0.09

136 ⫾ 27 124 ⫾ 24 0.04

156 ⫾ 32 147 ⫾ 35 0.01

Conclusion: Regular moderate physical activity resulted in 12% decrease of mean VR in patients with chronic permanent AF. Regular physical exercise also increased exercise capacity while reducing VR during physical exertion. Physical training should be taken into account in those patients in whom drug therapy does not allow to reach adequate VR control during AF. P4-55 AREA OF LIGAMENT OF MARSHALL AND CORONARY SINUS MUSCULATURE CAN CONTRIBUTE TO MAINTENANCE OF ATRIAL FIBRILLATION DURING PULMONARY VEIN-LEFT ATRIAL ELECTRICAL ISOLATION BY ELECTROGRAM-GUIDED ANTRUM ABLATION Kikuya Uno, MD, PhD, Seiichiro Sakurai, MD, Kenjiro Minamoto, MD, Shinya Shimoshige, MD, Naofumi Kaneko, MD, Naofumi Kaneko, MD, Takuji Yoshioka, MD, Atsuko Muranaka, MD, Satoshi Yuda, MD, PhD, Akiyoshi Hashimoto, MD, PhD, Kazufumi Tsuchihashi, MD, PhD and Kazuaki Shimamoto, MD, PhD. Sapporo Medical University School of Medicine, Sapporo, Japan and Teine Keijinkai Hospital, Sapporo, Japan. Purpose: Ligament of Marshall (LOM) in human was anatomically identified in the area of anterior left carina (lt-carina) located at anterior left pulmonary veins (PV) to LA annulus connecting coronary sinus (LOMend). To examine whether LOM can contribute to AF trigger and driver, we performed electrogram-guided antrum-pulmonary vein isolation (PVI) with targets of lt-carina and LOM-end. Methods: We performed PVI in 31 AF patients (18 males; 576 yrs) by double hi-density ring catheters. After completion of PVI, AF was reinduced under isoproterenol infusion, and additional ablation was performed at lt-carina and LOM-end with high-frequency fractionated electrogram (HFFE) during AF. Data sampling of recorded electrograms and Fast Fourier Transform analysis (FFT) were obtained. Results: 1) AF was terminated during PVI in 85%, and 64% of termination occurred during lt-carina ablation. 2) In non-terminated AF, dominant frequency (DF) was significantly shifted higher after lt-carina ablation. In reinitiated AF after complete PVI, 3) additional ablation of lt-carina and LOM-end with HFFE terminated reinduced AF in 64%. FFT of reinduced AF revealed that 4) DF was also shifted significantly higher by LOM-end. 5) Sustained AF was not inducible after additional ablation at lt-carina and LOM-end with HFFE in 81% of patients. Conclusion: LOM can be arrhythmogenic in AF related with AF maintenance. And HFFE at LOM site may reflect electrical activation enhanced by isoproterenol. P4-56 ENTRAINMENT OF SUPRAVENTRICULAR TACHYCARDIA FROM THE BASAL RIGHT VENTRICLE IMPROVES DIAGNOSTIC YIELD Aliasghar Khadem, MD, Ratika Parkash, MD, FRCP, Martin J. Gardner, MD, FRCP, Magdy N. Basta, MD and John L. Sapp, Jr., MD, FRCP. QEII Health Science Centre, Halifax, Halifax, Nova Scotia, Canada. Background: Typical AVNRT with concentric retrograde activation sequence and atypical AVNRT with eccentric retrograde activation can be misdiagnosed as orthodromic AVRT using a septal accessory pathway or orthodromic AVRT using a left sided accessory pathway respectively. It is sometimes difficult to differentiate one from the other. We hypothesized that