Anand R. Ramdat Misier

Long-term results of irrigated radiofrequency modified maze procedure in 200 patients with concomitant cardiac surgery: six years experience

BACKGROUND The Cox maze procedure is considered an effective surgical treatment of atrial fibrillation in patients with and without organic heart disease. Radiofrequency energy offers an alternative to the complex surgical maze procedure. We used the radiofrequency modified maze III procedure in patients with atrial fibrillation undergoing elective concomitant cardiac surgery. This study evaluated the long-term results of the irrigated radiofrequency ablation to create linear lines of conduction block endocardially. METHODS Between November 1995 and June 2001, 200 patients with mainly structural heart disease and chronic atrial fibrillation underwent intraoperative radiofrequency linear ablation in both atria with concomitant cardiac surgery. RESULTS The in-hospital mortality rate was 3.5% (7 patients) and during the mean follow-up of 40 months (range, 12 to 80) 27 patients (13.5%) died. Eight patients (4%) were lost from follow-up and complete data were available in 158 survivors. Sinus or atrial rhythm was present in 116 patients (73.4%) and an atrial driven rhythm in 10 patients (6.3%) with an atrioventricular pacemaker. Atrial fibrillation or flutter was documented in 32 patients (20.3%). Antiarrhythmic drugs were used in 49% of survivors who were free of atrial fibrillation or flutter. CONCLUSIONS Intraoperative radiofrequency endocardial ablation is an effective technique to eliminate atrial fibrillation with promising long-term results.

Successful Radiofrequency Ablation in Patients With Previous Atrial Fibrillation Results in a Significant Decrease in Left Atrial Size

Background— The objective of the present study was to evaluate the relation between freedom from atrial fibrillation (AF) and left atrial (LA) size in patients who underwent circumferential pulmonary vein (PV) isolation and LA ablation. Methods and Results— One hundred five consecutive patients with symptomatic and drug-refractory paroxysmal or persistent AF were included in the present study. The mean age was 52±9.5 years (range, 27 to 75 years); 74 patients (70%) were male. Paroxysmal AF was present in 52 (49.5%) and persistent AF in 53 (50.5%) patients. Mean AF duration was 6.0±5.1 years in the paroxysmal AF group and 7.6±6.0 years in the persistent AF group. A 3D electroanatomic map of the LA including the PV ostia was constructed with a nonfluoroscopic navigation system (Carto, Biosense Webster). Left- and right-sided PVs were encircled by continuous radiofrequency ablation lines. We performed 128 ablation procedures in 105 patients, ie, 23 redo procedures. The mean long-term follow-up duration was 14.6±4.9 months (range, 6 to 24 months). Sinus rhythm was present in 45 patients (86.5%) in the paroxysmal AF group and in 41 patients (77.3%) in the persistent AF group at the latest follow-up. Six months after ablation, LA dimension in the persistent AF subjects who remained in sinus rhythm decreased from 44.0±5.8 to 40±4.5 mm (range, 31 to 51 mm). In contrast, in patients with recurrences of AF, LA dimension increased from 45±6.5 to 49±5.4 mm (range, 32 to 59 mm). In the successfully treated paroxysmal AF group, LA dimension decreased from 40.5±4.4 to 37.5±3.5 mm (P<0.01). Conclusions— In radiofrequency ablation of AF using an electroanatomic approach, there is a statistically significant relationship between medium-term procedural success and LA size: persistent sinus rhythm is associated with reduced and recurrent AF with increased LA dimensions.

Randomized, double blind study of non-excitatory, cardiac contractility modulation electrical impulses for symptomatic heart failure

AIMS We performed a randomized, double blind, crossover study of cardiac contractility modulation (CCM) signals in heart failure patients. METHODS AND RESULTS One hundred and sixty-four subjects with ejection fraction (EF) < 35% and NYHA Class II (24%) or III (76%) symptoms received a CCM pulse generator. Patients were randomly assigned to Group 1 (n = 80, CCM treatment 3 months, sham treatment second 3 months) or Group 2 (n = 84, sham treatment 3 months, CCM treatment second 3 months). The co-primary endpoints were changes in peak oxygen consumption (VO2,peak) and Minnesota Living with Heart Failure Questionnaire (MLWHFQ). Baseline EF (29.3 +/- 6.7% vs. 29.8 +/- 7.8%), VO2,peak (14.1 +/- 3.0 vs. 13.6 +/- 2.7 mL/kg/min), and MLWHFQ (38.9 +/- 27.4 vs. 36.5 +/- 27.1) were similar between the groups. VO2,peak increased similarly in both groups during the first 3 months (0.40 +/- 3.0 vs. 0.37 +/- 3.3 mL/kg/min, placebo effect). During the next 3 months, VO2,peak decreased in the group switched to sham (-0.86 +/- 3.06 mL/kg/min) and increased in patients switched to active treatment (0.16 +/- 2.50 mL/kg/min). MLWHFQ trended better with treatment (-12.06 +/- 15.33 vs. -9.70 +/- 16.71) during the first 3 months, increased during the second 3 months in the group switched to sham (+4.70 +/- 16.57), and decreased further in patients switched to active treatment (-0.70 +/- 15.13). A comparison of values at the end of active treatment periods vs. end of sham treatment periods indicates statistically significantly improved VO2,peak and MLWHFQ (P = 0.03 for each parameter). CONCLUSION In patients with heart failure and left ventricular dysfunction, CCM signals appear safe; exercise tolerance and quality of life (MLWHFQ) were significantly better while patients were receiving active treatment with CCM for a 3-month period.

The radiofrequency modified maze procedure. A less invasive surgical approach to atrial fibrillation during open-heart surgery

OBJECTIVE Patients with mitral valve disease and suffering of atrial fibrillation of more than 1 years duration have a low probability of remaining in sinus rhythm after valve surgery alone. Intraoperative radiofrequency ablation was used as an alternative to simplify the surgical maze procedure. METHODS Seventy-two patients with mitral valve disease, aged 63+/-11 years ranging from 31 to 80 years, underwent valve surgery and radiofrequency energy applied endocardially, based on the maze III procedure to eliminate the arrhythmia. The right-sided maze was performed on the beating heart and the left-sided maze during aorta cross-clamping. RESULTS Surgical procedures included mitral valve repair (n=38) or replacement (n=34) and in addition tricuspid valve repair (n=42), closure of an atrial septal defect (n=2) and correction of cor triatriatum (n=1). The left-sided maze needed 14+/-3 min extra ischemic time. There were two in-hospital deaths (2.7%) and three patients (4.2%) died during follow-up of 20+/-15 months. Among 67 surviving patients, 51 patients (76%) were in sinus rhythm, two patients (3%) had an atrial rhythm and eight patients (12%) had persistent atrial fibrillation or atrial flutter. Four patients had a pacemaker implanted, in one patient because of sinus node dysfunction. Doppler echocardiography in 64 patients demonstrated right atrial contractility in 89% and left atrial transport in 91% of patients. CONCLUSIONS Intraoperative radiofrequency ablation of atrial fibrillation is an effective and less invasive alternative for the original maze procedure to eliminate atrial fibrillation.

Dispersion of ‘Refractoriness’ in Noninfarcted Myocardium of Patients With Ventricular Tachycardia or Ventricular Fibrillation After Myocardial Infarction

BACKGROUND Postinfarction ventricular tachycardias (VTs) may degenerate into ventricular fibrillation (VF), but this does not happen in all patients. The underlying mechanism is not exactly known, but dispersion of refractory periods is considered a major factor in both induction and persistence of reentrant arrhythmias in general. Hypertrophied, noninfarcted myocardium has altered electrophysiological characteristics. We hypothesized that noninfarcted ventricular tissue may provide the heterogeneities that cause the transition from VT into VF. Local fibrillation intervals, ie, the average interval between local activations during VF, have previously been shown to correlate well with local refractoriness in human and canine atrium and in porcine and canine ventricle and may therefore be used as an index of local refractoriness. This technique permits simultaneous assessment of refractoriness at multiple sites. METHODS AND RESULTS We measured local fibrillation intervals at 32 to 64 sites in the noninfarcted part of the left ventricle in patients undergoing antiarrhythmic surgery for symptomatic, drug-refractory, postinfarction ventricular tachyarrhythmias. The grid of electrodes (interelectrode distance, 7 mm) was attached to the epicardium of the left ventricle remote from the infarcted tissue. Group 1 consisted of 7 patients with hemodynamically tolerable sustained VT (VT group). Group 2 consisted of 7 patients with cardiac arrest and documented VF (VF group). With the patients on cardiopulmonary bypass, VF was induced by multiple premature stimulation. The VF interval was not significantly different in the two study groups (VT group, 136 +/- 5.5 ms; VF group, 129 +/- 3.4 ms, mean +/- SEM). However, spatial dispersion of the VF intervals (remote from the infarcted area) expressed as the coefficient of variation of VF intervals (SD x 100/mean VF interval in each heart) was significantly larger in the VF group. It was 3.63 +/- 0.56 in the VF group and 1.55 +/- 0.40 in the VT group (mean +/- SEM; P < .01). Differences between the shortest and longest VF intervals in one and the same heart and the largest difference between two adjacent sites were also larger in the VF group (P < .02 and P < .05, respectively). CONCLUSIONS This study shows larger dispersion in VF intervals and therefore suggests larger dispersion of refractory periods in parts of the myocardium remote from the infarction in patients with postinfarction VF than in patients with postinfarction VT.

Efficacy of multi-electrode duty-cycled radiofrequency ablation for pulmonary vein disconnection in patients with paroxysmal and persistent atrial fibrillation

AIM A novel multi-electrode pulmonary vein ablation catheter (PVAC) combining circular mapping and duty-cycled multi-electrode radiofrequency (RF) energy delivery has been developed to map and isolate the pulmonary veins (PVs). The aim of this study was to assess the efficacy of multi-electrode RF ablation using the PVAC device. METHODS AND RESULTS A total of 102 consecutive patients, age 57.9 +/- 9.6 years, with paroxysmal or persistent drug refractory atrial fibrillation (AF) were referred for ablation. All patients had documented AF episodes with an AF duration of 9.3 +/- 7.5 years (range 1.5-25). The mean total procedure time was 139.30 +/- 37.72 (median 135, range 115-172). The mean fluoroscopy time required for PVAC ablation was 17 +/- 12 min (median 16, range 12-33) and the total fluoroscopy time was 32.1 +/- 11.3 min (median 29, range 25-39). The mean multi-electrode RF ablation time required to achieve complete PV isolation was 31 +/- 6.7 min (range 16-51). In eight patients with persistent AF, additional ablations were performed to defragment septal and posterior part of the left atrium. In five patients additional RF ablations using conventional catheters were necessary. After multi-electrode duty-cycled RF ablation, 62 of 102 (60.8%) patients were in sustained sinus rhythm without anti-arrhythmic drugs. The mean follow-up duration was 12.2 +/- 3.9 months (range 6-15). CONCLUSION This novel multi-electrode ablation technique can be used for PV isolation and left atrium ablation with a relatively low medium-term success rate after the first ablation of approximately 61%. Larger studies with longer follow-up are required to evaluate the efficacy and whether multi-electrode RF ablation is associated with a different complication rate compared with standard PV isolation.

Dominant frequency of atrial fibrillation correlates poorly with atrial fibrillation cycle length.

Background—Localized sites of high frequency during atrial fibrillation (AF) are used as target sites to eliminate AF. Spectral analysis is used experimentally to determine these sites. The purpose of this study was to compare dominant frequencies (DF) with AF cycle length (AFCL) of unipolar and bipolar recordings. Methods and Results—Left and right atrial endocardial electrograms were recorded during AF in 40 patients with lone AF, using two 20-polar catheters. Mean age was 53±9.9 years. Unipolar and bipolar electrograms were recorded simultaneously during 16 seconds at 2 right and 4 left atrial sites. AFCLs and DFs were determined. QRS subtraction was performed in unipolar signals. DFs were compared with mean, median, and mode of AFCLs; 4800 unipolar and 2400 bipolar electrograms were analyzed. Intraclass correlation was poor for all spectral analysis protocols. Best correlation was accomplished with DFs from unipolar electrograms compared with median AFCL (intraclass correlation coefficient, 0.67). A gradient in median AFCL of >25% was detected in 16 of 40 patients. In 13 of 16 patients (81%) with a frequency gradient of >25%, the site with highest frequency was located in the left atrium (posterior left atrium in 8 patients). The site with shortest median AFCL and highest DF corresponded in 25% if unipolar and in 31% if bipolar electrograms were analyzed. Conclusions—DFs from unipolar and bipolar electrograms recorded during AF correlated poorly with mean, median, and mode AFCL. If a frequency gradient >25% existed, the site with highest DF corresponded to the site of shortest median AFCL in only 25% of patients. Because spectral analysis is being used to identify ablation sites, these data may have important clinical implications.

Predictive factors of sustained sinus rhythm and recurrent atrial fibrillation after a radiofrequency modified Maze procedure

BACKGROUND Preoperative atrial fibrillation (AF) in patients scheduled for elective open-heart surgery is a well-known phenomenon. The cut and sew Maze procedure or variant Maze procedures abolish AF in 45-95% of patients during short- to intermediate-term follow-up. We determined preoperative and postoperative factors predictive of sustained sinus rhythm (SR) and recurrent AF in an elderly cohort of patients with structural heart disease who underwent cardiac surgery. PATIENTS AND METHODS From November 1995 to November 2003, 285 patients with structural heart disease and permanent AF were scheduled for elective cardiac surgery. All patients underwent a radiofrequency (RF) modified Maze procedure as an adjunct to the open-heart operation. Patients were followed in the outpatient clinic or follow-up data were obtained from attending doctors. Patients are being followed in an ongoing registry; however for the patients who are the subject of this paper follow-up ended November 2006. Preoperative factors predicting recurrent AF postoperatively were assessed, as were factors associated with sustained SR. RESULTS Two hundred and eighty-five patients (mean age 68.0+/-9.6 years) underwent a total of 655 open-heart procedures and concomitant RF Maze surgery. In-hospital mortality was 4.6% (13 patients). Mean and median duration of AF were 60.9+/-68.7 months and 26 months (range 6-396), respectively. Median follow-up was 36.5 months (range 27-114 months). Sustained SR, including atrial rhythm or an atrial-based paced rhythm was present in 59% of patients at 1 year, in 54.4% at 3 years, in 53.4% at 5 years and in 57.1% of patients at the latest follow-up. Stroke was reported in six patients (2.1%). Factors predictive of postoperative AF recurrence were duration of permanent AF, preoperative atrial fibrillation wave and preoperative left atrial (LA) size. Postoperative angiotensin converting enzyme (ACE) inhibitor therapy was associated with SR during follow-up. LA size decreased during follow-up in patients with sustained SR, whereas LA size increased in case of recurrent AF. CONCLUSIONS In this group of elderly patients with permanent AF in the setting of structural heart disease who underwent cardiac surgery and a RF Maze procedure as a concomitant procedure, the duration of AF, preoperative atrial fibrillation wave and preoperative LA size were predictive of recurrent AF, whereas left ventricular ejection fraction, left ventricular diameters and invasive hemodynamic parameters were not. Postoperative ACE inhibitor therapy was associated with sustained SR. Furthermore, sustained SR after RF Maze surgery was associated with decreased LA dimensions.

Intermediate to Long-Term Results of Radiofrequency Modified Maze Procedure as an Adjunct to Open-Heart Surgery

BACKGROUND Of patients scheduled for elective open heart surgery, a substantial number of patients have preoperative atrial fibrillation (AF). The cut-and-sew Maze procedure and variant Maze procedures abolish AF in 45% to 95% during short- to intermediate-term follow-up. Limited data are available about maintenance of sinus rhythm during intermediate- to long-term follow-up. The objective of the present study was to assess the association between postoperative rhythm and mortality and stroke. METHODS From November 1995 to November 2003, 258 patients with structural heart disease and permanent AF with a duration of longer than 12 months were scheduled for elective cardiac surgery and included in a registry. They underwent a radiofrequency modified Maze procedure as an adjunct to the open heart operation. Patients were followed in the outpatient clinic, and follow-up data were obtained from medical correspondence of attending physicians. For this paper, follow-up ended November 2006; however, patients are being followed in an ongoing registry. RESULTS Two hundred fifty-eight patients (mean age, 68.1 +/- 9.5 years) with permanent AF underwent cardiac surgical procedures and concomitant radiofrequency Maze surgery; 213 patients (82.5%) underwent more than one procedure. Mean duration of permanent AF was 66.6 +/- 69.8 months (range, 16 to 96). Preoperatively, 82.9% of patients were in New York Heart Association class III. In-hospital mortality was 3.9% (10 patients), and during a mean follow-up of 43.7 +/- 25.9 months (range, 27 to 114), 73 patients (28.3%) died. Left ventricular ejection fraction was normal in 44.6%, moderately decreased in 42.5%, and poor in 12.9% of patients. Sustained sinus rhythm, including atrial rhythm or an atrial-based paced rhythm was present in 69% of patients at 1 year, in 56% at 3 years, in 52% at 5 years, and in 57% of patients at the latest follow-up. Antiarrhythmic drugs were used by 64% of survivors who were free of atrial fibrillation. Oral anticoagulation therapy was taken by 99% of patients. Stroke was reported in 4 patients (1.6%). CONCLUSIONS The RF modified Maze procedure abolishes AF in the majority of patients with structural heart disease and longstanding permanent AF. Postoperative rhythm was not predictive of all-cause mortality, cardiac mortality, and stroke, neither in the whole group nor in the subgroups defined by preoperative left ventricular ejection fraction and New York Heart Association class. The stroke rate was very low in this group with longstanding AF.

Multisite or Alternate Site Pacing for the Prevention of Atrial Fibrillation

The role of permanent pacing in preventing atrial fibrillation in patients at risk for this arrhythmia is a relatively new concept. Existing retrospective studies support the superiority of atrial-based pacing over ventricular stimulation with respect to lowering the incidence of atrial fibrillation. Constant rate overdrive pacing has been shown to reverse abnormalities in conduction or refractoriness that are dependent on bradycardia and suppress atrial ectopic complexes. Multisite (biatrial and dual right atrial) pacing is a promising concept. The antiarrhythmic mechanism is not well understood, but atrial resynchronization and reduction of site-dependent conduction delay of atrial premature complexes may be relevant. The cardiology community awaits additional data from prospective trials that are currently underway.