Slow wall motion rather than electrical conduction delay underlies mechanical dyssynchrony in postinfarction patients with narrow QRS complex.

INTRODUCTION: The mechanism of mechanical dyssynchrony in postinfarction patients with a narrow QRS complex is not defined but essential for cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Left ventricular electrical activation and subsequent wall motion were recorded for 16 patients with ischemic cardiomyopathy during intrinsic rhythm using a modified NOGA electromechanical mapping system. Ten patients presented mechanical dyssynchrony on tissue Doppler imaging, while 6 patients served as control subjects. The local activation time (LAT) was set by the maximum downslope of the unipolar electrogram. Local wall motion time (LMT) was defined as the time needed for the catheter tip to traverse half of its maximum inward deflection during systole. LAT and LMT were measured relative to the onset of the QRS complex. Electrical activation showed a septal-to-lateral pattern in all patients with a mean endocardial activation time of 65 +/- 13 ms. Control subjects exhibited 97.5% of all LMTs <290 +/- 17 ms. Delayed motion areas (cut-off LMT > 300 ms) showed no slowing of conduction. Wall motion time corrected for differences in electrical activation (LMT-LAT) was significantly longer in delayed (289 +/- 34 ms) than in regular (204 +/- 24 ms) motion areas (P = 0.002). Delayed motion segments were hypokinetic on echocardiography and presented a lower maximum inward motion (9.9 +/- 1.1 mm) compared to regular segments (10.9 +/- 1.2 mm) on electromechanical maps (P = 0.004). Viability, however, was preserved with unipolar and bipolar voltage amplitude >7 mV and >1.5 mV for 79% of all delayed motion areas. CONCLUSION: Dyssynchronous segments of an ischemic myocardium show unimpaired local activation but slow wall motion, thereby limiting the benefit of ventricular preexcitation via CRT.

Anatomical variations of the right coronary artery may be a source of difficult block and conduction recurrence in catheter ablation of common-type atrial flutter.

AIMS: Although Eustachian valves and recesses have been related to resistance to block, the effect of convective cooling by the right coronary artery (RCA) has not been evaluated in the clinical setting. METHODS AND RESULTS: The distance and course of the RCA in relation to the cavotricuspid isthmus (CTI) in addition to variants of CTI anatomy and the presence of Eustachian valves were analysed from computed tomography scans of 54 patients. Ablation power was titrated using a step-up protocol. Invasive follow-up was available for 34 patients. The RCA came closest to the CTI inferiorly separated by a mean of 5.3 ± 2.5 mm compared with 7.3 ± 3.3 mm septally and 5.7 ± 2.3 mm anteriorly (P < 0.01). The maximum power required for CTI block correlated inversely with the distance of the RCA to the CTI, whereas the cumulative energy was highest in the presence of recesses. Neither failure of acute block nor a higher rate of conduction recurrence could be attributed to variants of CTI anatomy or the presence of a Eustachian valve. Using multivariate analysis, a position of the RCA underneath the central part of the CTI was the only significant predictor for late conduction recurrence. These patients showed a 2.7 mm larger distance of the RCA to the tricuspid valve plane (P = 0.05). CONCLUSION: The RCA affects CTI ablation as higher power settings are required at closer distances to the ablation site. Late conduction recurrences were observed in patients with a variation of the RCA, leaving the atrioventricular groove towards the atrial aspect.

Impact of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers on the long-term outcome after pulmonary vein isolation for paroxysmal atrial fibrillation.

OBJECTIVES: The effect of angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARBs) on the long-term outcome after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) is unknown. METHODS: This matched-pair study included 102 patients with PAF treated with ACE-I or ARBs (group 1) and 102 control subjects (group 2) after standardized PVI. Tele-ECG recorders were used to detect the end point of the first PAF recurrence after a 3-month blanking period. RESULTS: Median follow-up was 2.1 years (range 0.3-6.3). In group 1, 51 (50%) patients suffered recurrences, with a mean time to recurrence of 3.2 years (95% CI 2.6-3.8). In group 2, 67 (65.7%) patients presented PAF after a mean period of 2.2 years (95% CI 1.7-2.8; p = 0.009). A second ablation was performed in 31 (50%) patients from the treatment group and in 48 (66.7%) patients from the control group (p = 0.02). Multivariate Cox analysis showed treatment with ACE-I and ARBs to be the only significant predictor of a reduced recurrence rate (HR 0.49, 95% CI 0.32-0.75). CONCLUSION: ACE-I and ARBs were effective for the preservation of sinus rhythm after PAF ablation, and they reduced the reablation rate.

Catheter ablation of multiple ventricular tachycardias after myocardial infarction guided by combined contact and noncontact mapping.

BACKGROUND: Insights gained from noncontact mapping of ventricular tachycardia (VT) have not been systematically applied to contact maps. This study sought to unify both techniques for an individualized approach to the patient with multiple ischemic VTs irrespective of cycle length. METHODS AND RESULTS: For 12 consecutive patients with chronic myocardial infarction and recurrent VT, bipolar contact maps were acquired during sinus or paced rhythm. Additional noncontact maps were obtained during 48 induced VTs (cycle length 192 to 579 ms). Endocardial exit sites were superimposed on contact maps and verified by pace-mapping. Radiofrequency lesions were extended for critical borders defined by multiple neighboring exits and followed the isovoltage contour line of contact maps. Nine critical borders were identified in 8 patients and constituted the substrate for 31 VTs. The voltage at exit sites was 0.8 mV (range 0.1 to 2.3). Noncontact maps revealed 23+/-18% of isthmus conduction. Thirty-seven (77%) of all and 83% of clinically documented VTs were rendered noninducible irrespective of cycle length by application of 27 radiofrequency lesions (range 18 to 56). Spontaneous transitions between distinct VTs along critical borders were demonstrated in 4 patients. Pace-mapping reproduced the QRS morphology of 81% of VTs and was associated with successful ablation (P<0.01). Noninducibility of any sustained VT was reached for 8 (67%) patients. During 15 months (range 5 to 28) of follow-up, 8 patients remained without recurrence, and VT episodes were reduced in the other 4 patients (P<0.01). VT cycle length was not predictive for acute or long-term success. CONCLUSIONS: The combined approach of contact and noncontact mapping effectively defines critical borders as the substrate of multiple VTs without limitation for unstable VTs.

Stable and unstable ventricular tachycardias in patients with previous myocardial infarction: a clinically oriented strategy for catheter ablation.

OBJECTIVE: Catheter ablation of ventricular tachycardia (VT) after myocardial infarction (MI) can be complex and time-consuming. We only targeted the previously documented VTs and those with similar or longer cycle lengths. METHODS: 30 patients with VTs after MI were included in the study. Voltage mapping was performed using an electro-anatomic mapping system (CARTOT). Stable VTs were mapped during tachycardia and unstable VTs during sinus rhythm. RESULTS: Clinical VTs were stable in 16 (53%) and unstable in 14 (47%) patients, and ablation was successful in 11 (69%) and 9 patients (64%), respectively (p = 0.42). During follow-up (14 +/- 6 months), 4 patients (25%) treated for stable and 6 (43%) for unstable VTs had recurrences (p = 0.82); ablation was successful in none and 2 (33%) of them, respectively. Non-target VTs were inducible in 11 (55%) of 20 patients after successful ablation and non-inducible in 9 (45%). During follow-up, inducibility of non-target VTs did not predict recurrences (9 vs. 11%, p = 0.88). CONCLUSIONS: Catheter ablation of VTs after MI can be successfully performed. Acute success rates seem to be similar for stable and unstable VTs. VTs faster than those documented clinically exert a minor effect on VT recurrences during follow-up.

Biphasic versus monophasic shock for external cardioversion of atrial flutter: a prospective, randomized trial.

BACKGROUND: External cardioversion is effective to terminate persistent atrial flutter. Biphasic shocks have been shown to be superior to monophasic shocks for ventricular defibrillation and atrial fibrillation cardioversion. The purpose of this trial was to compare the efficacy of rectilinear biphasic versus standard damped sine wave monophasic shocks in symptomatic patients with typical atrial flutter. METHODS: 135 consecutive patients were screened, 95 (70 males, mean age 62 +/- 13 years) were included. Patients were randomly assigned to a monophasic or biphasic cardioversion protocol. Forty-seven patients randomized to the monophasic protocol received sequential shocks of 100, 150, 200, 300 and 360 J. Forty-eight patients with the biphasic protocol received 50, 75, 100, 150 or 200 J. RESULTS: First-shock efficacy with 50-Joule, biphasic shocks (23/48 patients, 48%) was significantly greater than with the 100-Joule, monophasic waveform (13/47 patients, 28%, p = 0.04). The cumulative second-shock efficacy with the 50- and 75-Joule, biphasic waveform (39/48 patients, 81%) was significantly greater than with the 100- and 150-Joule, monophasic waveform (25/47 patients, 53%, p < 0.05). The cumulative efficacy for the higher energy levels showed naturally no significant difference between the two groups. The amount of the mean delivered energy was significantly lower in the biphasic group (76 +/- 39 J) compared to the monophasic one (177 +/- 78 J, p < 0.05). CONCLUSIONS: For transthoracic cardioversion of typical atrial flutter, biphasic shocks have greater efficacy and the mean delivered current is lower than for monophasic shocks. Therefore, biphasic cardioversion with lower starting energies should be recommended.

Catheter motion during atrial ablation due to the beating heart and respiration: impact on accuracy and spatial referencing in three-dimensional mapping.

BACKGROUND: The accuracy of three-dimensional mapping systems is affected by cardiac contraction and respiration. OBJECTIVE: The study sought to determine relative motion of cardiac and thoracic structures to assess positional errors and guide the choice of an optimized spatial reference. METHODS: Motion of catheters placed at the coronary sinus (CS), pulmonary vein (PV) ostia, left atrial (LA) isthmus and roof, cavotricuspid isthmus (CTI), and right atrial appendage (RAA) were recorded for 30 patients using Ensite-NavX. The right subclavian vein, left brachiocephalic vein, azygos vein, pulmonary arteries, and a static reference were included. The displacement from a mean position was calculated for each pair of sites. Respiration effects were assessed by the shift of the motion curve during in- and expiration phases. RESULTS: The PVs showed a mean interpair displacement of 4.1 +/- 0.2 mm and a shift of 5.0 +/- 0.5 mm. Proximal CS references for all LA structures (4.0 +/- 1.1 mm) were superior to the static reference (4.9 +/- 0.7 mm; P = .01). In addition, the shift due to respiration was less pronounced at 3.5 +/- 0.8 mm versus 4.9 +/- 0.5 mm (P = .004), respectively. Motion of extracardiac vessels was influenced by a mean shift of 6.8 +/- 1 mm. The remote subclavian and brachiocephalic veins were more affected (7.6 +/- 0.7 mm) than the pulmonary arteries (5.9 +/- 0.4 mm; P = .002). For the CTI, a minimized mean displacement of less than 4.6 +/- 2.0 mm relative to the proximal CS, RAA, and azygos vein was found. CONCLUSION: Respiration is the major source of relative motion, which increases with distance from the heart. For LA procedures, a proximal CS reference position is superior to a static reference position.

Catheter based simultaneous mapping of cardiac activation and motion: a review.

Heart failure as a result of a variety of cardiac diseases is an ever growing, challenging condition that demands profound insight in the electrical and mechanical state of the myocardium. Assessment of cardiac function has largely relied on evaluation of cardiac motion by multiple imaging techniques. In recent years electrical properties have gained attention as heart failure could be improved by biventricular resynchronization therapy. In contrast to early belief, QRS widening as a result of left bundle branch block could not be identified as a surrogate for asynchronous contraction. The combined analysis of electrical and mechanical function is yet a largely experimental approach. Several mapping system are principally capable for this analysis, the most prominent being the NOGA-XP system. Electromechanical maps have concentrated on the local shortening of the reconstructed endocardial surface from end-diastole to end-systole. Temporal analysis of motion propagation, however, is a new aspect. The fundamental principles of percutaneous catheter based activation and motion assessment are reviewed. Related experimental setups are presented and their main findings discussed.

Simultaneous mapping of activation and motion timing in the healthy and chronically ischemic heart.

BACKGROUND: Experimental data of simultaneous acquired activation and motion (AM) propagation from human subjects are not available. OBJECTIVES: The purpose of this study was to demonstrate the feasibility of a novel mapping technique allowing combined analysis of AM timing in vivo and to delineate the influence of chronically ischemic tissue on cardiac AM propagation. METHODS: Ten patients with remote myocardial infarction and 4 control patients were studied during sinus rhythm using electroanatomic mapping (CARTO). Maps of the left ventricle were obtained via the retrograde aortic approach. Real-time catheter positions were extracted using custom-made software. Catheter motion was analyzed along a static line connecting the catheter tip with the apex. Tissue Doppler measurements in all patients provided data for validation. RESULTS: Four shapes of catheter motion curves were identified and correlated to healthy tissue with variable degrees of preloading, scar tissue and dyskinetic regions, e.g. aneurysms. An analysis of the AM-delay revealed areas of delayed activation in 7, and slow motion onset in 4 patients. Tissue Doppler data correlated well with local onset of motion (correlation coefficient 0,99). CONCLUSION: Activation delays as well as long AM-intervals that can be differentiated with the described mapping technique are responsible for asynchronous contraction in the ischemic heart. Myocardial wall motion abnormalities can be derived from catheter motion curves.

Comparison of antero-lateral versus antero-posterior electrode position for biphasic external cardioversion of atrial flutter.

External cardioversion is an established and very important tool to terminate symptomatic atrial flutter. The superiority of the biphasic waveform has been demonstrated for atrial flutter, but whether electrode position affects the efficacy of cardioversion in this population is not known. The aim of this trial was to evaluate whether anterior-lateral (A-L) compared with anterior-posterior (A-P) electrode position improves cardioversion results. Of 130 screened patients, 96 (72 men, mean age 62 +/- 12 years) were included and randomly assigned to a cardioversion protocol with either A-L or A-P electrode position. In each group, 48 patients received sequential biphasic waveform shocks using a step-up protocol consisting of 50, 75, 100, 150, or 200 J. The mean energy (65 +/- 13 J for A-L vs 77 +/- 13 J for A-P, p = 0.001) and mean number of shocks (1.48 +/- 1.01 for A-L vs 1.96 +/- 1.00 for A-P, p = 0.001) required for successful cardioversion were significantly lower in the A-L group. The efficacy of the first shock with 50 J in the A-L electrode position (35 of 48 patients [73%]) was also highly significantly greater than the first shock with 50 J in the A-P electrode position (18 of 48 patients [36%]) (p = 0.001). In conclusion, the A-L electrode position increases efficacy and requires fewer energy and shocks in external electrical cardioversion of common atrial flutter. Therefore, A-L electrode positioning should be recommended for the external cardioversion of common atrial flutter.

Decennial follow-up in patients with recurrent tachycardia originating from the right ventricular outflow tract: electrophysiologic characteristics and response to treatment.

AIMS: In the setting of right ventricular outflow tract-tachycardia (RVOT-T), data about long-term follow-up (FU) with respect to the therapeutic strategies are missing. All patients (pts) referred to our institution during the last 20 years for the treatment of RVOT-T were studied in a retrospective analysis to assess mortality and efficacy of treatment. METHODS AND RESULTS: One hundred and thirty-three patients (77 female; 39+/-13 years) with sustained RVOT-T were included in this study. At the time of first presentation, diagnosis of RVOT-T was made by complete invasive and non-invasive diagnostic assessment, including electrophysiology study and two-dimensional echocardiography. After 135+/-68 months (median 136, range 29-248), patients were invited to undergo clinical assessment. Of the 133 pts, 127 (95%) survived and six (5%) died from non-cardiac disease. Anti-arrhythmic (AA) drugs were given to 62 of the 133 pts (47%); of them 32 (52%) had recurrences during follow-up. The mean time to recurrence was 10.02 years (95% CI 7.46-12.59). The other 71 study patients (53%) underwent catheter ablation. The procedure was successful in 58 pts (82%). During follow-up, 30 (52%) of the 58 successfully treated patients had recurrences of RVOT-T. The mean time to recurrence was 6.28 years (95% CI 4.96-7.6). RVOT-T recurrences were similar in morphology to those treated previously in 33% and different in 67% of cases. CONCLUSIONS: Long-term follow-up in patients with RVOT-T is favourable. Catheter ablation is effective in this setting. However, late recurrences with similar or different morphology may arise in half of the patients after initially successful treatment. AA drug therapy is a valid initial therapeutic option, since it is effective in about half of the patients.

Correlation of symptoms to ECG diagnosis following atrial fibrillation ablation.

INTRODUCTION: Currently, definition of success following atrial fibrillation (AF) ablation is commonly based on the lack of symptoms. The purpose of this study was to evaluate the correlation between symptoms and the underlying rhythm after AF ablation. METHODS AND RESULTS: Eighty consecutive patients (pts) were treated for paroxysmal episodes of AF by segmental ostial ablation of all pulmonary veins and right atrial isthmus ablation. For 6 months pts transmitted transtelephonic (T-) ECG recordings in combination with comments daily or in the event of symptoms. Eligible comments were classified as: (1) asymptomatic, (2) symptomatic. Analysis was performed at 1-month intervals, defining an acute (first month) and chronic period (second to sixth month) after ablation. Overall 6,835 T-ECGs were analyzed. Of these 5,437 (79.5%) showed sinus rhythm (SR) and 1,398 (20.5%) showed AF. Pts in SR reported symptoms for 593 (10.9%) episodes, whereas 4,844 (89.1%) episodes were asymptomatic. During AF, 646 (46.2%) episodes were associated with symptoms, and 752 (53.8%) episodes remained asymptomatic. Exclusively asymptomatic were 7 (8.8%) pts. In 30 (52.6%) of 57 pts with AF, arrhythmic events were confined to the acute phase. Of the remaining 27 pts 14 (52%) reported an improvement, 12 (44%) the same, and 1 (4%) worsened symptoms after 3 months. A significant change (P < 0.01) toward more asymptomatic episodes from the acute (43.5%) to the chronic (57.5 +/- 4.5%) period was evident. CONCLUSION: Assessment of success after AF ablation cannot be based on the absence of symptoms due to a high prevalence of asymptomatic episodes.

Efficacy and safety of radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in the elderly.

INTRODUCTION: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common regular supraventricular tachycardia in the general population as well as in elderly patients. The purpose of the study was to investigate the success and complication rate particularly regarding the induction of an atrioventricular (AV) block by radiofrequency (RF) ablation in elderly patients with and without a preexisting AV block. METHODS AND RESULTS: Between February 1998 and July 2004, all patients with symptomatic AVNRT referred for slow-pathway ablation in our institution were included and divided into two groups: group 1 patients younger than 75 years (n = 508) and group 2 patients > or =75 years (n = 70). A preexisting prolonged PR interval was present in 17 (3.3%) patients of group 1 and in 26 (37%, P < 0.0001) patients of group 2. Following successful slow-pathway ablation (follow-up time group 1: 37 +/- 22, group 2: 37 +/- 24 months) no induction of an AV block was observed in group 2 but in four patients of group 1 (0.79%) a complete heart block was induced requiring a pacemaker implantation. In group 1, 15 (2.95%) patients with a recurrence of AVNRT were readmitted for a repeat ablation procedure. No recurrences occurred in group 2. CONCLUSION: Despite a higher incidence of preexisting prolonged PR intervals slow-pathway ablation in elderly patients is both effective and safe and should be considered as the first line therapy also in this patient population.

Catheter ablation of common-type atrial flutter guided by three-dimensional right atrial geometry reconstruction and catheter tracking using cutaneous patches: a randomized prospective study.

INTRODUCTION: EnSite NavX (NavX) is a novel mapping and navigation system that allows visualization of conventional catheters for diagnostic and ablative purposes and uses them to create a three-dimensional (3D) geometry of the heart. NavX is particularly suitable for ablation procedures utilizing an anatomic approach, as in the setting of common-type atrial flutter (AFL). The aim of this study was to compare NavX-guided and conventional ablation procedures for AFL. METHODS AND RESULTS: Forty consecutive patients (32 male, 59 +/- 12 years) with documented AFL were randomized to undergo fluoroscopy-guided (group I, 20 patients) or NavX-guided (group II, 20 patients) ablation, including 3D isthmus reconstruction. The same catheter setup was used in both groups. The endpoint of bidirectional isthmus block was obtained in all patients. Compared to conventional approaches, NavX-guided procedures significantly reduced fluoroscopy time (5.1 +/- 1.4 min vs 20 +/- 11 min, P < 0.01) and total x-ray exposure (5.1 +/- 3.1 Gycm2 vs 24.9 +/- 1.6 Gycm2, P < 0.01). Isthmus geometry reconstruction could be performed in all patients of group II. In 4 patients (20%) of group II, anatomic isthmus variations were detected by NavX. No significant differences in radiofrequency current applications and procedural times were found between the two groups. CONCLUSION: NavX technology allows geometry reconstruction of the cavotricuspid isthmus. NavX-guided ablation of AFL reduces total x-ray exposure compared to the fluoroscopy-guided approach but does not prolong procedure time.