Patient acceptance of subcutaneous versus transvenous defibrillator systems: A multi-center experience.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an effective alternative to the transvenous ICD. No study has yet compared S-ICD and transvenous ICD by assessing patient acceptance as a patient-centered outcome. OBJECTIVE: To evaluate the patient acceptance of the S-ICD and to investigate its association with clinical and implantation variables. In patients with symptomatic heart failure and reduced ejection fraction (HFrEF), the acceptance of the S-ICD was compared with a control group of patients who received a transvenous ICD. METHODS: Patient acceptance was calculated with the Florida Patient Acceptance Survey (FPAS) which measures four factors: return to function (RTF), device-related distress (DRD), positive appraisal (PA), and body image concerns (BIC). The survey was administered 12 months after implantation. RESULTS: 176 patients underwent S-ICD implantation. The total FPAS and the single factors did not differ according to gender, body habitus, or generator positioning. Patients with HFrEF had lower FPAS and RTF. Younger patients showed better RTF (75 [56-94] vs. 56 [50-81], p = .029). Patients who experienced device complications or device therapies showed higher DRD (40 [35-60] vs. 25 [10-50], p = .019). Patients with HFrEF receiving the S-ICD had comparable FPAS, RTF, DRD, and BIC to HFrEF patients implanted with the transvenous ICD while exhibited significantly better PA (88 [75-100] vs. 81 [63-94], p = .02). CONCLUSIONS: Our analysis revealed positive patient acceptance of the S-ICD, even in groups at risk of more distress such as women or patients with thinner body habitus, and regardless of the generator positioning. Among patients receiving ICDs for HFrEF, S-ICD was associated with better PA versus transvenous ICD.

Reproducibility of pulmonary vein isolation guided by the ablation index: 1-year outcome of the AIR registry.

BACKGROUND: Ablation index (AI) is a new lesion quality marker that has been demonstrated to allow a high single-procedure arrhythmia-free survival in single-center studies. This prospective, multi-center study was designed to evaluate the reproducibility of pulmonary vein (PV) isolation guided by the AI. METHODS: A total of 490 consecutive patients with paroxysmal (80.4%) and persistent AF underwent first time PV isolation and were divided in four study groups according to operator's preference in choosing the ablation catheter (a contact force (ST) or contact force surround flow (STSF) catheter) and the AI setting (330-450 or 380-500 at anterior wall or posterior wall, respectively). RESULTS: At 12 months a high rate of freedom from AF recurrences was observed in patients with both paroxysmal and persistent AF (91% vs 83.3%; P = .039). There was no difference in the rate of AF recurrence among the four study groups (4.5% in group ST330-450, 12.2% in group ST 380-500, 14.9% in group STSF330-450, 9.4% in group STSF380-500; P = .083). Recurrence was also similar between patients treated with a ST (8%) or STSF catheter (12.1%; P = .2), and within patients targeting an AI settings of 330 to 450 (10.9%) or 380 to 500 (10.3%; P = .64). In patients with paroxysmal AF, there was no difference (P = .12) in the 1-year freedom from AF recurrence among 14 operators that performed ≥10 ablation procedure. CONCLUSIONS: An ablation protocol respecting strict criteria for contiguity and quality lesion resulted in high rate of 1-year freedom from AF recurrence, irrespective of the ablation catheters, AI settings, and operator.

Detection of oesophageal course during left atrial catheter ablation.

BACKGROUND: Oesophageal changes and injuries were recorded after atrial fibrillation(AF) ablation procedures. The reduction of power in the posterior left atrial(LA) wall(closest to the oesophagus) and the monitoring of temperature in the oesophagus(OE) reduced oesophageal injuries. The intracardiac-echocardiography(ICE) with a Cartosound module provides two-dimensional imaging (2D) to assess detailed cardiac anatomy and its relationship with the OE. The aim of this study was to highlight the safety and feasibility of 3D-reconstruction of the oesophageal course in left atrial catheter ablation(CA) procedures without OE temperature probe or quadripolar catheter to guide ICE OE reconstruction. METHODS: 180 patients(PT) underwent left atrial ablation. AF ablation were 125(69.5%); incisional left atrial tachycardias(IAFL) were 37(20.6%); left atrial tachycardias(LAT) were 19(10.6%). The LA and pulmonary vein anatomies were rendered by traditional electroanatomic mapping(EAM) and merged with an ICE anatomic map. In 109 PT ICE imaging was used to create a geometry of the OE(group A). A quadripolar catheter was used in 71 PT to show OE course associated to ICE(group B). RESULTS: Ablation energy delivery was performed outside the broadest OE anatomy borders. The duration of procedures was longer in group B vs group A Fluoroscopy time was lower in Group A than Group B(Group A 7 ± 3.2 vs 19.2 ± 2.4 min; p < 0.01). CONCLUSIONS: OE monitoring with ICE is safe and feasible. Oesophageal anatomy is complex and variable. Many PT will have a broad oesophageal boundary, which increases the risk of untoward thermal injury during posterior LA ablation. ICE with 3D construction of the OE enhances border detection of the OE, and as such, should decrease the risk of oesophageal injury by improving avoidance strategies without intra-oesophageal catheter visualization.

From near-zero to zero fluoroscopy catheter ablation procedures.

AIMS: The use of electroanatomical mapping (EAM) systems can reduce radiation exposure (RX) and it can also completely eliminate the use of RX. Radiation exposure related to conventional radiofrequency ablation procedures can have a stochastic and deterministic effect on health. The main aim of this study was to evaluate the safety and feasibility of an entirely nonfluoroscopic approach to catheter ablation (CA) using EAM CARTO3. METHODS: In 2011 we started an RX-minimization programme in all procedures using the CARTO system with the deliberate intention to not resort to the aid of RX unless strictly necessary. We divided procedures into two groups (group 1: from 2011 to 2013; group 2: from 2014 to 2017). The only exclusion criteria were the need for transseptal puncture, and nonidiopathic ventricular tachycardia (VT). RESULTS: From a total of 525 procedures, we performed CA entirely without RX in 78.5% of cases. From 2011 to 2013, we performed CA without RX in 38.5% of cases; from 2014 to 2017, we performed 96.2% of cases with zero RX. The use of RX was significantly reduced in group 2 (group 2: 1.4 ± 19.6 seconds vs group 1: 556.92 ± 520.76 seconds; P < .001). These differences were irrespective of arrhythmia treatment. There were no differences between the two groups in acute success, complications, or duration of procedures. CONCLUSION: CA of supraventricular tachycardia and VT entirely without RX, guided by the CARTO system, is safe, feasible, and effective. After an adequate learning curve, CA can be performed entirely without RX.

Steam pop during cavo-tricuspid isthmus ablation shown by intracardiac echocardiography.

Steam pop (SP) refers to audible sound related to the intramyocardial explosion when tissue temperatures reach 100 °C. In this case the SP was recorded using intracardiac echocardiography (ICE), using Sound-star probe and Smart-touch catheter with ablation index (AI) module (Biosense-Webster Inc., Diamond-Bar, CA, USA). Guided by the anatomical reconstruction (EAM) and electrograms, we applied radiofrequencies (RF) in a "point-by-point" along the entire line on cavo-tricuspid-isthmus (CTI) using a target of an AI ≥500. The tip-tissue force recorded was 12-18 g and a power of 35 W. ICE imaging was important so that the anatomical position of the catheter tip can be precisely monitored. During RF, ICE showed a growing, hyperechogenic intramyocardial bubble at the catheter-tissue interface. ICE imaging showed a hyperechogenic intramyocardial formation at the moment of occurrence of the SP. ICE imaging showed that the formation suddenly expanded to a sphere over the course of several seconds. After SP we reduced the RF output energy from 35 W to 30 W. After RF line on CTI the patient had no complications and no recurrence of atrial flutter was recorded. .

Catheter inversion during cavotricuspid isthmus catheter ablation: The new shaft visualization catheter reduces fluoroscopy use.

AIMS: Catheter ablation (CA) is the choice therapy of cavotricuspid isthmus (CTI) atrial flutter. The aim of this study was to describe our approach to improve the CTI ablation using a zero-fluoroscopy (ZF). The procedural difficulties could be related to anatomical characteristics of the CTI. METHODS: One hundred eighty-eight patients that performed CA of CTI were retrospectively and consecutively evaluated between 2017 and 2019. The studied population was divided into two groups. Eighty-eight patients who were undergone CA using ablation catheter without shaft visualization catheter (NSV) were Group 1. One hundred patients were undergone CA using ablation catheter with a shaft visualization (SV); they were Group 2. The catheter was looped at the Eustachian ridge after 200 seconds of radiofrequencies (RF) without elimination of local electrogram. RESULTS: A conduction line block of CTI was obtained in all patients of Group 2 using a ZF approach. In 16 patients of Group 1, the catheter inversion was obtained using fluoroscopy to avoid damages during its loop. In Group 2, a complete CTI block was obtained with a catheter inversion approach in ten patients without fluoroscopy, visualizing the shaft and the tip of the ablation catheter on the electroanatomic (EAM) map. In the overall population studied the use of SV had a linear correlation with the ZF approach (r = .629; P < .001). The duration of RF was lower in Group 2 than in Group 1 (Group 1: 27.8 ± 6.3 vs Group 2: 15.6 ± 7.2 minutes; P < .01). The procedure time between two groups was lower in Group 2 than in Group 1 (Group 1: 58.4 ± 22.4 vs Group 2: 42.2 ± 15.7 minutes; P < .01). No differences between two groups were documented regarding success and complications. CONCLUSIONS: The visualization of the shaft's catheter on the EAM permitted the catheter inversion safely in order to overcome some complex CTI anatomy and obtain bidirectional block. The SV reduced procedure time, RF applications and fluoroscopy exposition during CTI ablation.

Zero-fluoroscopy atrial fibrillation ablation in the presence of a patent foramen ovale: a multicentre experience.

INTRODUCTION: Atrial fibrillation ablation has historically been guided by fluoroscopy, with the related enhanced risk deriving from radiation. Fluoroscopy exposure may be confined to guide the transseptal puncture. Small sample size study presented a new methodology to perform a totally fluoroless atrial fibrillation ablation in the case of a patent foramen ovale (PFO). We evaluated this methodology in a large sample size of patients and a multicentre experience. METHODS AND RESULTS: Two hundred and fifty paroxysmal atrial fibrillation patients referred for first atrial fibrillation ablation with a CARTO3 electroanatomic mapping system were enrolled. In 58 out of 250 patients, a PFO allowed crossing of the interatrial septum, and a completely fluoroless ablation was performed applying the new method (Group A). In the remaining patients, a standard transseptal puncture was performed (Group B). Pulmonary vein isolation was achieved in all patients with comparable procedural and clinical outcomes at short- and long-term follow-up. CONCLUSION: The presence of a PFO may allow a completely fluoroless well tolerated and effective atrial fibrillation ablation. Probing the fossa ovalis looking for the PFO during the procedure is desirable, as it is not time-consuming and can potentially be done in every patient undergoing atrial fibrillation ablation.

Relation of C-reactive protein to long-term risk of recurrence of atrial fibrillation after electrical cardioversion.

The aim of this study is to assess the role of C-reactive protein (CRP) in predicting long-term risk of atrial fibrillation (AF) recurrence after electrical cardioversion. CRP levels are associated with the presence of AF and failure of electrical or pharmacologic cardioversion, but no previous study has assessed their predictive role in long-term follow-up after successful electrical cardioversion. One hundred two consecutive patients (age 67 +/- 11 years; 58 men) with nonvalvular persistent AF who underwent successful biphasic electrical cardioversion were studied. High-sensitivity CRP was measured immediately before cardioversion. Follow-up was performed up to 1 year in all cases. Patients were divided into 4 groups according to CRP quartiles. Patients in the lowest CRP quartile (<1.9 mg/L) had significantly lower rates of AF recurrence (4% vs 33% at 3 months in the other 3 groups combined, p = 0.007, and 28% vs 60% at 1 year, p = 0.01). The 4 groups were similar in age, gender, ejection fraction, and left atrial size. Survival analysis confirmed that patients in the lowest CRP quartile had a lower recurrence rate (p = 0.02). Cox regression analyses using age, gender, hypertension, diabetes, ejection fraction, left atrial diameter, use of antiarrhythmic drugs, angiotensin-converting enzyme inhibitors or angiotensin II antagonists, and statins, and CRP quartiles as covariates showed that only CRP was independently associated with AF recurrence during follow-up (hazard ratio 4.98, 95% confidence interval 1.75 to 14.26, p = 0.003). In conclusion, low CRP is associated with long-term maintenance of sinus rhythm after cardioversion for nonvalvular AF.

N-3 Fatty acids for the prevention of atrial fibrillation after coronary artery bypass surgery: a randomized, controlled trial.

OBJECTIVES: The aim of this study was to assess the efficacy of preoperative and postoperative treatment with n-3 polyunsaturated fatty acids (PUFAs) in preventing the occurrence of atrial fibrillation (AF) after coronary artery bypass graft surgery (CABG). BACKGROUND: Postoperative AF is a common complication of CABG. There is growing clinical evidence that PUFAs have cardiac antiarrhythmic effects. METHODS: A total of 160 patients were prospectively randomized to a control group (81 patients, 13 female, 64.9 +/- 9.1 years) or PUFAs 2 g/day (79 patients, 11 female, 66.2 +/- 8.0 years) for at least 5 days before elective CABG and until the day of discharge from the hospital. The primary end point was the development of AF in the postoperative period. The secondary end point was the hospital length of stay after surgery. All end points were independently adjudicated by two cardiologists blinded to treatment assignment. RESULTS: The clinical and surgical characteristics of the patients in the two groups were similar. Postoperative AF developed in 27 patients of the control group (33.3%) and in 12 patients of the PUFA group (15.2%) (p = 0.013). There was no significant difference in the incidence of nonfatal postoperative complications, and postoperative mortality was similar in the PUFA-treated patients (1.3%) versus controls (2.5%). After CABG, the PUFA patients were hospitalized for significantly fewer days than controls (7.3 +/- 2.1 days vs. 8.2 +/- 2.6 days, p = 0.017). CONCLUSIONS: This study first demonstrates that PUFA administration during hospitalization in patients undergoing CABG substantially reduced the incidence of postoperative AF (54.4%) and was associated with a shorter hospital stay.

Atrial flutter and atrial fibrillation: which relationship? New insights into the electrophysiological mechanisms and catheter ablation treatment.

Atrial fibrillation (AF) and atrial flutter (AFL) are two arrhythmias commonly associated in clinical practice. This association generally reflects a similar arrhythmogenic substrate. It has been observed that the development of isthmus-dependent AFL is often preceded by AF. The conversion from AF to AFL develops thanks to a line of functional block in the right atrial free wall. In this subset a particular condition is represented by typical AFL that occurs during the treatment with class IC or III antiarrhythmic drugs in patients with previous AF. A hybrid approach (antiarrhythmic drugs and catheter ablation) has been proposed as a possible treatment of drug-induced AFL. The conversion from AFL to AF is less frequent and may be due to several mechanisms: a shortening of the length of the line of functional block, atrial ectopic beats or rapid atrial rhythm, focal activation from the pulmonary veins, alternans of atrial action potentials. Also, atypical right and left AFL can determine AF. Finally, atypical AFL may occur after AF ablation, and could be prevented by associated cavotricuspid isthmus ablation.

Recovery of cardiac function after ablation of atrial tachycardia arising from the tricuspid annulus.

Tachycardia-induced cardiomyopathy is a reversible form of heart failure. An early diagnosis and an effective cure of the underlying tachycardia are crucial for a favorable outcome. Different kinds of atrial and ventricular arrhythmias may induce tachycardiomyopathy. Focal atrial tachycardia may be easily suppressed by means of transcatheter ablation. Relationships between focal atrial tachycardia and tachycardiomyopathy have not been deeply analyzed. In the present paper we report a case of a 76-year-old man with tachycardia-induced cardiomyopathy caused by recurrences of focal atrial tachycardia arising from the tricuspid annulus. The arrhythmia was successfully treated with transcatheter ablation. In the follow-up no recurrences of the arrhythmia occurred and a significant improvement in myocardial function was observed.

Catheter ablation of idiopathic ventricular tachycardia without the use of fluoroscopy.

BACKGROUND: Catheter ablation is the treatment of choice for many patients with idiopathic ventricular tachycardia (VT). Unfortunately, conventional catheter ablation is guided by fluoroscopy, which is associated with a small but definite radiation risk for patients and laboratory personnel. The aim of our study is to assess feasibility, success rate and safety of idiopathic VT ablation procedure performed without the use of fluoroscopy. METHODS: Nineteen consecutive patients undergoing idiopathic VT ablation at our institution have been included. The ablation procedures were performed under the guidance of electroanatomical mapping (EAM) system and intracardiac echocardiography (ICE). RESULTS: Nineteen patients (mean age 38.7 years) underwent ablation procedure for idiopathic VT. Twelve (63%) had outflow tract VT, 3 (18%) fascicular tachycardia, 2 (11%) peri-tricuspidal VT, 1 (5%) peri-mitral VT, and 1 (5%) lateral left free-wall VT. The mean procedural time was 170.2 ± 45.7 min. No fluoroscopy was used in any procedural phase. Acute success rate was 100%. No complication was documented in any patients. After a mean follow up of 18 ± 4 months, recurrences occurred in 2 patients. CONCLUSIONS: In our preliminary experience idiopathic VT ablation without the use of fluoroscopy was feasible and safe, using a combination of EAM and ICE. Success rate was excellent with no complication.

Long-term monitoring of respiratory rate in patients with heart failure: the Multiparametric Heart Failure Evaluation in Implantable Cardioverter-Defibrillator Patients (MULTITUDE-HF) study.

BACKGROUND: Monitoring respiratory rate (RR) is recommended at the time of hospital presentation for acute decompensation in heart failure (HF). Device-based continuous monitoring of RR may be helpful for diagnostic and prognostic stratification after implantable cardioverter-defibrillator (ICD) implantation. This study was undertaken to analyze short- and long-term changes in ICD-measured RR and to relate RR with the patient's clinical status and the occurrence of HF events. METHODS: One hundred twenty-four consecutive HF patients who received ICD endowed with this diagnostic capability (Boston Scientific Inc., Natick, MA, USA) were prospectively enrolled. Patients were followed up for 12 months. RESULTS: At the baseline, the proportion of New York Heart Association (NYHA) class III-IV was higher among patients with daily maximum RR >27 breaths/min (third tertile) than those with <24 breaths/min (first tertile) (43 vs. 23%, p < 0.05). Moreover, the ejection fraction was lower (27 ± 7 vs. 34 ± 8%, p < 0.05). In patients with HF hospitalizations (33 events) and urgent visits for HF (15 events), the weekly average of RR calculated over the 7 days preceding hospital accesses did not differ from values recorded at the baseline and before scheduled follow-up visits. However, the weekly variation in RR (i.e., the difference between maximum and minimum values collected over the week) was significantly higher prior to hospitalization (p < 0.05). A weekly variation >3 breaths/min in maximum RR predicted an impending hospital admission for HF with sensitivity of 73 % and specificity of 57%. CONCLUSIONS: In this study, elevated values of ICD-monitored RR identified patients with worse functional status and lower systolic function. The weekly variation in RR increased before HF exacerbation. This monitoring technology may represent a useful tool in the clinical management of patients with HF.

Transseptal activation during left atrial pacing in humans: electroanatomic mapping using a noncontact catheter and the intracardiac echocardiography.

BACKGROUND: A better understanding of transseptal activation may be important for the treatment of atrial fibrillation, but little is known about preferential routes of conduction from the left atrium (LA) to the right atrium (RA) in humans. METHODS AND RESULTS: Twelve patients were studied. A noncontact mapping system was used to map the RA during pacing from several sites of LA at different cycle lengths. The location of the Bachmann's bundle (BB), the fossa ovalis (FO) and the coronary sinus (CS) ostium were determined using intracardiac echocardiography. The BB was the earliest area of right atrial activation during pacing from the atrial appendage, roof and postero-superior wall in 94% of cases. The FO was the area of earliest activation during pacing from the septum and the right superior pulmonary veins (PV) in 95% of cases. The CS ostium (alone or associated with the FO) was the region of transseptal breakthrough in all patients during pacing from the right inferior PV, postero-inferior wall and distal CS. Various patterns of activation with 2 or 3 distinct areas of transseptal breakthrough were observed during pacing from the lateral wall and the left superior PV. The pacing cycle length did not influence the modality of transseptal activation. CONCLUSIONS: Different patterns of transseptal activation were found during pacing from LA. The preferential routes of conduction from the LA to the RA were related to the sites of stimulation and were not influenced by the pacing cycle length.

Risk stratification for arrhythmic events in patients with idiopathic dilated cardiomyopathy: a review of the literature and current perspectives.

The prognosis for patients with idiopathic dilated cardiomyopathy (DCM) has markedly improved during the last decade, mainly because of advancements in therapeutic strategies. However, sudden death still accounts for a significant part of the total mortality in patients with moderate disease. Recent primary prophylactic trials failed to demonstrate any benefit of cardioverter-defibrillator implantation in an unselected group of idiopathic DCM patients and thus the identification of the subgroup of patients at high arrhythmic risk is crucial. Although different risk stratification methods have been evaluated in risk assessment, the reported clinical value differs in studies, mainly because of differences in either methodology and/or patient selection. The present review focuses on arrhythmic events in idiopathic DCM and on the value of noninvasive methods and electrophysiological study in the risk stratification of this group of patients.

Transesophageal low-energy cardioversion of atrial fibrillation without fluoroscopy outside the electrophysiology laboratory.

BACKGROUND: Low-energy internal cardioversion (LEIC) is a safe and effective procedure for the restoration of sinus rhythm in patients with atrial fibrillation refractory to external cardioversion. However, the procedure needs fluoroscopy and the use of the electrophysiology laboratory, even when the esophageal approach is utilized. The aim of this study was to assess the efficacy, safety and tolerability of a new simplified procedure of esophageal LEIC performed without fluoroscopy, outside the electrophysiology laboratory. METHODS: Thirty consecutive patients (23 males, 7 females) with persistent atrial fibrillation were submitted to LEIC using a step-up protocol (by steps of 50 V, starting from 200 V). Twenty (66%) were resistant to external cardioversion. A large surface area lead (cathode) was positioned within the esophagus, 45 cm from the nasal orifice. A second large surface area lead (anode) was positioned in the right atrium via the right internal jugular vein without fluoroscopic control. Synchronization of delivery of the shock with the QRS was achieved by means of two cutaneous electrodes positioned on the thoracic wall. RESULTS: Sinus rhythm was restored in 28 patients (93%) with a mean delivered energy of 15.2 +/- 7.5 J (range 5-27 J) and a mean impedance of 48.3 +/- 5.6 Ohm. No complication occurred during and after the procedure that was well tolerated under sedation. CONCLUSIONS: This new technique of performing esophageal LEIC is effective and seems to be safe and well tolerated. In this way internal cardioversion can be performed without fluoroscopy, outside the electrophysiology laboratory.

Atrial flutter: arrhythmia circuit and basis for radiofrequency catheter ablation.

The term atrial flutter was introduced 90 years ago for an arrhythmia with a unique electrocardiographic pattern. The development of endocardial mapping techniques in the last decade allowed the detailed characterization of the tachycardia circuit and the identification of the cavotricuspid isthmus as its critical part. This review stresses the position of atrial flutter in the new classification of atrial tachycardias and focuses on its unique electrophysiological characteristics and different variants described in humans. Transcatheter radiofrequency ablation across the cavotricuspid isthmus constitutes a feasible and safe therapy, which prevents flutter recurrences during the long-term follow-up. This paper describes the different techniques that validate bidirectional isthmus block, which is an important endpoint for successful ablation.

Atrioventricular nodal reentrant tachycardia: anatomical and electrophysiological considerations.

Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common regular narrow QRS tachycardias. Although the principal understanding of the physiology of dual atrioventricular conduction as a substrate for the reentry mechanism in AVNRT has not changed during the last 25 years, there is still some uncertainty with regard to the exact circuit delineation. At least four forms of AVNRT have been described and several possible circuits have been proposed. Although the refinement of our knowledge about AVNRT seems to be purely academic since further insight will probably not increase the success rate of treatment by radiofrequency catheter ablation, AVNRT continues to puzzle both clinical and basic electrophysiologists. The authors summarize our present knowledge about AVNRT and stress the unique features of the atrioventricular junction anatomy and the current opinions on the reentrant impulse propagation.

Relations between monophasic action potential duration and refractoriness after cardioversion of persistent atrial fibrillation: results in wash-out and amiodarone-treated patients.

BACKGROUND: The relation between repolarization and refractoriness has been clinically evaluated both in the atrium and ventricle. However, this relation has not been carefully investigated in the atria of patients with persistent atrial fibrillation after cardioversion. METHODS: We determined the refractoriness and monophasic action potential duration at 90% of repolarization (MAP90), at 5 pacing cycle lengths (300 to 700 ms) and in 5 right atrial sites after internal cardioversion of persistent atrial fibrillation in 27 patients. RESULTS: The effective refractory periods (ERPs) were longer in amiodarone-treated patients (group 1) than in wash-out patients (group 2) (211.3 +/- 26.4 vs 199.1 +/- 24.3 ms, p < 0.002) as well as the MAP90 (243.6 +/- 36.8 vs 223.1 +/- 29.2 ms, p < 0.001). Linear regression analysis showed a direct relation between the MAP90 and ERP changes induced by different pacing cycle lengths (r = 0.77 and r = 0.92 in the amiodarone and wash-out patients, respectively). The ERP/MAP90 ratio was similar at all pacing cycle lengths in both wash-out and amiodarone groups and was always < 1. The mean ERP and MAP90 were shorter in the lateral right atrial sites than in the atrial roof and septum in both group 1 and group 2 patients (p < 0.001). CONCLUSIONS: A linear correlation was found between ERP and MAP90 in response to changes in pacing cycle lengths. Postrepolarization refractoriness was not observed after cardioversion of persistent atrial fibrillation. Pretreatment with oral amiodarone does not affect these electrophysiological features or the dispersion of ERP and MAP90 in the right atrium after sinus rhythm restoration.

Electropharmacological effects of antiarrhythmic drugs on atrial fibrillation termination. Part I: Molecular and ionic fundamentals of antiarrhythmic drug actions.

In the last few years many studies have been performed with the aim of gaining a better understanding of the pathophysiological nature of atrial fibrillation. These recent observations provide new insights into the initiation and perpetuation of atrial fibrillation, underlying the importance of the pulmonary veins as major sources of atrial triggers and introducing new concepts such as the atrial electrical remodeling and the spatial heterogeneity of the electrophysiological characteristics of this arrhythmia. The increasing knowledge about the cardiac ion channel structure and function and about the electrophysiological actions of the antiarrhythmic drugs may contribute to a better comprehension of the mechanisms of the pharmacological termination of the arrhythmia. In part I of the review we try to give a unified vision of the old models and new concepts about the molecular and ionic fundamentals of antiarrhythmic drug actions.