Jonas Carlson

Clinical Predictors of Termination and Clinical Outcome of Catheter Ablation for Persistent Atrial Fibrillation

OBJECTIVES This study evaluated the role of pre-procedural clinical variables to predict procedural and clinical outcomes of catheter ablation in patients with long-lasting persistent atrial fibrillation (AF). BACKGROUND Catheter ablation of persistent AF remains a challenging task. METHODS Catheter ablation was performed in 90 patients (76 men, age 57 +/- 11 years) with long-lasting persistent AF. The history of AF, echocardiographic parameters, presence of structural heart disease, and surface electrocardiogram (ECG) AF cycle length (CL) were assessed before ablation and analyzed with respect to procedural termination and clinical outcome. Mean follow-up was 28 +/- 4 months. RESULTS Persistent AF was terminated in 76 of 90 patients (84%) by ablation. The duration of continuous AF was shorter (p < 0.0001), the surface ECG AFCL was longer (p < 0.0001), and the left atrium was smaller (p < 0.01) in patients in whom AF was terminated by catheter ablation. The surface ECG AFCL was the only independent predictor of AF termination (p < 0.01). Maintenance of sinus rhythm was associated with a shorter duration of continuous AF (p < 0.0001), a longer surface ECG AFCL (p < 0.001), and a smaller left atrium (p < 0.05) compared with those with recurrent arrhythmia. In multivariate analysis, the surface ECG AFCL and the AF duration predicted clinical success of persistent AF ablation (p < 0.01 and p < 0.05, respectively). CONCLUSIONS The surface ECG AFCL is a clinically useful pre-ablation tool for predicting patients in whom sinus rhythm can be restored by catheter ablation. The duration of continuous AF and the surface ECG AFCL are predictive of maintenance of sinus rhythm.

Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: validation of P-wave morphology using electroanatomic mapping in man.

BACKGROUND Different P-wave morphologies during sinus rhythm as displayed on standard ECGs have been postulated to correspond to differences in interatrial conduction. OBJECTIVE The purpose of this study was to evaluate the hypothesis by comparing P-wave morphologies using left atrial activation maps. METHODS Twenty-eight patients (mean age 49 +/- 9 years) admitted for ablation of paroxysmal atrial fibrillation were studied. Electroanatomic mapping of left atrial activation was performed at baseline during sinus rhythm with simultaneous recording of standard 12-lead ECG. Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology. The morphology was subsequently classified into one of three predefined types. All analyses were blinded. RESULTS The primary left atrial breakthrough site was the fossa ovalis in 8 patients, Bachmann bundle in 18, and coronary sinus in 2. Type 1 P-wave morphology was observed in 9 patients, type 2 in 17, and type 3 in 2. Seven of eight patients with fossa ovalis breakthrough had type 1 P-wave morphology, 16 of 18 patients with Bachmann bundle breakthrough had type 2 morphology, and both patients with coronary sinus breakthrough had type 3 P-wave morphology. Overall, P-wave morphology criteria correctly identified the site of left atrial breakthrough in 25 (89%) of 28 patients. CONCLUSION In the vast majority of patients, P-wave morphology derived from standard 12-lead ECG can be used to correctly identify the left atrial breakthrough site and the corresponding route of interatrial conduction.

Ultrasound enhanced thrombolysis in experimental retinal vein occlusion in the rabbit

AIMS To investigate if it was possible to lower the dose of streptokinase and maintain an effective thrombolysis by adding pulsed low energy ultrasound. Methods—53 retinal veins in 27 rabbits were occluded by rose bengal enhanced laser treatment. Six rabbits were treated with streptokinase (50 000 IU/kg), 10 rabbits were treated with a low dose of streptokinase (25 000 IU/kg), and 11 rabbits were treated with a low dose of streptokinase (25 000 IU/kg) and pulsed ultrasound during 1 hour. Fluorescein angiography was performed immediately before the thrombolytic treatment and after 12 hours. RESULTS In the group treated with streptokinase (50 000 IU/kg) all vessels were open. In the group that was given streptokinase (25 000 IU/kg), 21% of the vessels were open. In the group that was treated with streptokinase (25 000 IU/kg) and ultrasound, 64% of the vessels were open. The difference between groups 2 and 3 is statistically significant (p= 0.011) CONCLUSION Adding pulsed low energy ultrasound makes it possible to lower the dose of streptokinase while maintaining a good thrombolytic effect.

Signal-averaged P wave analysis for delineation of interatrial conduction – Further validation of the method

BackgroundThe study was designed to investigate the effect of different measuring methodologies on the estimation of P wave duration. The recording length required to ensure reproducibility in unfiltered, signal-averaged P wave analysis was also investigated. An algorithm for automated classification was designed and its reproducibility of manual P wave morphology classification investigated.MethodsTwelve-lead ECG recordings (1 kHz sampling frequency, 0.625 μV resolution) from 131 healthy subjects were used. Orthogonal leads were derived using the inverse Dower transform. Magnification (100 times), baseline filtering (0.5 Hz high-pass and 50 Hz bandstop filters), signal averaging (10 seconds) and bandpass filtering (40–250 Hz) were used to investigate the effect of methodology on the estimated P wave duration. Unfiltered, signal averaged P wave analysis was performed to determine the required recording length (6 minutes to 10 s) and the reproducibility of the P wave morphology classification procedure. Manual classification was carried out by two experts on two separate occasions each. The performance of the automated classification algorithm was evaluated using the joint decision of the two experts (i.e., the consensus of the two experts).ResultsThe estimate of the P wave duration increased in each step as a result of magnification, baseline filtering and averaging (100 ± 18 vs. 131 ± 12 ms; P < 0.0001). The estimate of the duration of the bandpass-filtered P wave was dependent on the noise cut-off value: 119 ± 15 ms (0.2 μV), 138 ± 13 ms (0.1 μV) and 143 ± 18 ms (0.05 μV). (P = 0.01 for all comparisons).The mean errors associated with the P wave morphology parameters were comparable in all segments analysed regardless of recording length (95% limits of agreement within 0 ± 20% (mean ± SD)). The results of the 6-min analyses were comparable to those obtained at the other recording lengths (6 min to 10 s).The intra-rater classification reproducibility was 96%, while the interrater reproducibility was 94%. The automated classification algorithm agreed with the manual classification in 90% of the cases.ConclusionThe methodology used has profound effects on the estimation of P wave duration, and the method used must therefore be validated before any inferences can be made about P wave duration. This has implications in the interpretation of multiple studies where P wave duration is assessed, and conclusions with respect to normal values are drawn.P wave morphology and duration assessed using unfiltered, signal-averaged P wave analysis have high reproducibility, which is unaffected by the length of the recording. In the present study, the performance of the proposed automated classification algorithm, providing total reproducibility, showed excellent agreement with manually defined P wave morphologies.

Age-related changes in P wave morphology in healthy subjects

BackgroundWe have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects.Methods120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies.ResultsOrthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed.ConclusionChanges of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided.

Abnormal P-Wave Morphology Is a Predictor of Atrial Fibrillation Development and Cardiac Death in MADIT II Patients

Background: Several ECG‐based approaches have been shown to add value when risk‐stratifying patients with congestive heart failure, but little attention has been paid to the prognostic value of abnormal atrial depolarization in this context. The aim of this study was to noninvasively analyze the atrial depolarization phase to identify markers associated with increased risk of mortality, deterioration of heart failure, and development of atrial fibrillation (AF) in a high‐risk population with advanced congestive heart failure and a history of acute myocardial infarction.

Variable interatrial conduction illustrated in a hypertrophic cardiomyopathy population.

Background: Patients with hypertrophic cardiomyopathy (HCM) have a high incidence of atrial fibrillation. They also have a longer P‐wave duration than healthy controls, indicating conduction alterations. Previous studies have demonstrated orthogonal P‐wave morphology alterations in patients with paroxysmal atrial fibrillation. In the present study, the P‐wave morphology of patients with HCM was compared with that of matched controls in order to explore the nature of the atrial conduction alterations.

Altered Interatrial Conduction Detected in MADIT II Patients Bound to Develop Atrial Fibrillation

Background: Changes in P‐wave morphology have recently been shown to be associated with interatrial conduction route used, without noticeable changes of P‐wave duration. This study aimed at exploring the association between P‐wave morphology and future atrial fibrillation (AF) development in the Multicenter Automatic Defibrillator Trial II (MADIT II) population.

Prediction of sinus rhythm maintenance following DC-cardioversion of persistent atrial fibrillation – the role of atrial cycle length

BackgroundAtrial electrical remodeling has been shown to influence the outcome the outcome following cardioversion of atrial fibrillation (AF) in experimental studies.The aim of the present study was to find out whether a non-invasively measured atrial fibrillatory cycle length, alone or in combination with other non-invasive parameters, could predict sinus rhythm maintenance after cardioversion of AF.MethodsDominant atrial cycle length (DACL), a previously validated non-invasive index of atrial refractoriness, was measured from lead V1 and a unipolar oesophageal lead prior to cardioversion in 37 patients with persistent AF undergoing their first cardioversion.Results32 patients were successfully cardioverted to sinus rhythm. The mean DACL in the 22 patients who suffered recurrence of AF within 6 weeks was 152 ± 15 ms (V1) and 147 ± 14 ms (oesophagus) compared to 155 ± 17 ms (V1) and 151 ± 18 ms (oesophagus) in those maintaining sinus rhythm (NS). Left atrial diameter was 48 ± 4 mm and 44 ± 7 mm respectively (NS). The optimal parameter predicting maintenance of sinus rhythm after 6 weeks appeared to be the ratio of the lowest dominant atrial cycle length (oesophageal lead or V1) to left atrial diameter. This ratio was significantly higher in patients remaining in sinus rhythm (3.4 ± 0.6 vs. 3.1 ± 0.4 ms/mm respectively, p = 0.04).ConclusionIn this study neither an index of atrial refractory period nor left atrial diameter alone were predictors of AF recurrence within the 6 weeks of follow-up. The ratio of the two (combining electrophysiological and anatomical measurements) only slightly improve the identification of patients at high risk of recurrence of persistent AF. Consequently, other ways to asses electrical remodeling and / or other variables besides electrical remodeling are involved in determining the outcome following cardioversion.

Detailed ECG Analysis of Atrial Repolarization in Humans

Introduction: Data on human atrial repolarization are scarce since the QRS complex normally obscures its ECG trace. In the present study, consecutive patients with third‐degree AV block were studied to better describe the human Ta wave.