Outcomes after transcatheter aortic valve replacement in older patients.

BACKGROUND: The prevalence of aortic valve stenosis is increasing due to the continuously growing geriatric population. Data on procedural success and mortality of very old patients are sparse, raising the question of when this population may be deemed as "too old even for transcatheter aortic valve replacement (TAVR)." We, therefore, sought to evaluate the influence of age on outcome after TAVR and the impact of direct implantation. METHODS: The data of 394 consecutive patients undergoing TF-TAVR were analyzed. Patients were divided into four age groups: ≤75 (group 1, n = 28), 76-80 (group 2, n = 107), 81-85 (group 3, n = 148), and >85 (group 4, n = 111) years. Direct implantation was performed when possible according to current recommendations. Survival was evaluated by Kaplan-Meier analysis. RESULTS: Mortality at 30 days and 1 year was not significantly different between the four age groups (3.6 vs. 6.7 vs. 5.4 vs. 2.7% and 7.6 vs. 17 vs. 14.5 vs. 13%m respectively, log-rank p = 0.59). Direct implantation without balloon aortic valvuloplasty was more frequently performed on patients aged >85 vs. ≤85 years (33.3 vs. 14.1%, p < 0.001). the incidence of procedural complications frequently associated with advanced age (stroke, vascular complications) was not significantly increased in group 4. CONCLUSION: Outcome after TF-TAVR is comparable among different age cohorts, even in very old patients. Direct implantation simplifies the procedure and could therefore play a role in reducing the incidence of peri-interventional complications in patients of advanced age.

Multipoint left ventricular pacing with large anatomical separation improves reverse remodeling and response to cardiac resynchronization therapy in responders and non-responders to conventional biventricular pacing.

BACKGROUND: Multipoint pacing [Multipoint™ Pacing (MPP), Abbott] via a single left ventricular lead (Quartet™ LV lead, Abbott) improves acute left ventricular (LV) function and response to cardiac resynchronization therapy (CRT). Aim of this study was to examine additional benefits in terms of LV reverse remodeling and CRT response by activating MPP in responders and non-responders to conventional biventricular pacing (CONV). METHODS: 43 consecutive patients receiving CRT (Quadra Assura MP™, Abbott) received LV dP/dtmax optimized CONV programming for 6 months. MPP programming with large anatomical electrode separation (> 30 mm) and basal LV1 pacing location was activated afterwards. Echocardiographic and clinical parameters were obtained at baseline, 6- and 12-month follow-up (FU). The response was defined as an improvement of LVESV ≥ 15% and super-response as improvement ≥ 30% relative to baseline. RESULTS: 41 patients completed FU (one died of non-cardiac cause and one was lost to FU) and after 6 months CONV, 26 patients (63%) were classified as CRT responders. With MPP, the response rate increased to 90% (p < 0.001). Super-response also improved significantly with MPP compared to CONV (71% vs. 22%; p < 0.005). LV reverse remodeling in terms of LVESV improved significantly with MPP compared to CONV (79 ± 45 ml vs. 103 ± 64 ml; p < 0.001). NYHA-class only improved significantly with CONV relative to baseline (1,8 ± 0,7 vs. 2,7 ± 0,5; p < 0.001), but not further with MPP (1,7 ± 0,6 vs. 1,8 ± 0,7; p = 0.49). CONCLUSION: Multipoint pacing significantly improves response and super-response to CRT as well as LV reverse remodeling compared to conventional biventricular pacing.

One-year outcome of percutaneous mitral valve repair in patients with severe symptomatic mitral valve regurgitation.

AIM: To investigate one-year outcomes after percutaneous mitral valve repair with MitraClip® in patients with severe mitral regurgitation (MR). METHODS Our study investigated consecutive patients with symptomatic severe MR who underwent MitraClip® implantation at the University Hospital Bergmannsheil from 2012 to 2014. The primary study end-point was all-cause mortality. Secondary end-points were degree of MR and functional status after percutaneous mitral valve repair. RESULTS: The study population consisted of 46 consecutive patients (mean logistic EuroSCORE 32% ± 21%). The degree of MR decreased significantly (severe MR before MitraClip® 100% vs after MitraClip® 13%; P < 0.001), and the NYHA functional classes improved (NYHA III/IV before MitraClip® 98% vs after MitraClip® 35%; P < 0.001). The mortality rates 30 d and one year after percutaneous mitral valve repair were 4.3% and 19.5%, respectively. During the follow-up of 473 ± 274 d, 11 patients died (90% due to cardiovascular death). A pre-procedural plasma B-type natriuretic peptide level > 817 pg/mL was associated with all-cause mortality (hazard ratio, 6.074; 95%CI: 1.257-29.239; P = 0.012). CONCLUSION: Percutaneous mitral valve repair with MitraClip® has positive effects on hemodynamics and symptoms. Despite the study patients' multiple comorbidities and extremely high operative risk, one-year outcomes after MitraClip® are favorable. Elevated B-type natriuretic peptide levels indicate poorer mid-term survival.

Initial Experience With Novel Oral Anticoagulants During the First 45 Days After Left Atrial Appendage Closure With the Watchman Device.

BACKGROUND: The use of oral anticoagulation or dual antiplatelet therapy (DAPT) is recommended within the first 45 days after left atrial appendage (LAA) closure using the Watchman device because of incomplete device endothelialization. This study reports for the first time the feasibility of novel oral anticoagulants (NOAC) in these patients. HYPOTHESIS: NOAC therapy is safe and effective after LAA closure. METHODS: Interventional LAA closure was performed successfully in 45 patients. Of these, 18 patients received NOAC during the first 45 days after implantation and 27 patients received DAPT. Transesophageal echocardiography was conducted 45 days after implantation. The primary study endpoint was abnormal thrombus apposition 45 days after implantation. Secondary study endpoints were death from any cause, major adverse cardiac and cerebrovascular events (MACCE), and major bleedings. RESULTS: After 45 days, transesophageal echocardiography revealed no abnormal thrombus apposition. During a follow-up of 417 ± 323 days, 7 patients died. No stroke or transient ischemic attack occurred. Nonfatal myocardial infarction occurred in 1 patient. There was a nonsignificant trend for lower all-cause mortality (P = 0.159) and occurrence of MACCE (P = 0.096) in the NOAC group compared with the DAPT group. Overall, 6 patients suffered from a major bleeding (NOAC, n = 3; DAPT, n = 3). In NOAC group, major bleedings (at day 205, 688, and 736) occurred long after termination of NOAC therapy. There was no significant difference in the frequency of major bleedings in different groups. CONCLUSIONS: Our pilot study suggests that NOAC therapy within the first 45 days after interventional LAA closure is safe and effective.

Three-year outcomes after transcatheter aortic valve implantation with the CoreValve prosthesis.

There is little known about the long-term results of the CoreValve prosthesis. The aim of this study was to assess the 3-year clinical and hemodynamic outcomes of the CoreValve prosthesis. One hundred fifty consecutive patients with severe aortic stenosis successfully underwent transcatheter aortic valve implantation (TAVI) with the CoreValve prosthesis. The primary study end point was death from any cause after TAVI. The secondary end points were defined as (1) cardiovascular death and (2) prosthesis-related mortality and morbidity. At 1 to 3 years, all-cause mortality rates were 25%, 32%, and 41%, respectively, and cardiovascular mortality rates were 14%, 21%, and 27%, respectively. Before TAVI, 95% of patients were in New York Heart Association class III or IV. Of the surviving patients, rates of New York Heart Association class III or IV at 1 to 3 years were 33%, 39%, and 38%, respectively. There was an annual decrease of the valve area of approximately 0.1 cm². Aortic restenosis occurred in 2 patients. Moderate or severe aortic regurgitation (AR) occurred in 15% of patients immediately after TAVI. Twenty patients (13%) had a slight worsening of AR within 3 years. New severe AR did not occur. The incidence of prosthesis-related endocarditis was 0.66% per year. Overall, 7 patients (incidence of 1.5% per year) had a clinically relevant problem of the prosthesis. In conclusion, TAVI with the CoreValve prosthesis had favorable effects on symptoms and outcomes even after 3 years. These results are clouded by side effects, such as AR and prosthesis-related mortality and morbidity.

Total atrial conduction time assessed by tissue doppler imaging (PA-TDI Interval) to predict early recurrence of persistent atrial fibrillation after successful electrical cardioversion.

BACKGROUND: The aim of this study was to investigate whether total atrial conduction time (TACT) assessed via tissue Doppler imaging (PA-TDI interval) can identify patients with early recurrent atrial fibrillation (ERAF) after successful direct-current electrical cardioversion (CV) of persistent atrial fibrillation (persPAF). METHODS AND RESULTS: A total of 54 patients without antiarrhythmic drug medication (mean ± SD: 66 ± 10.4 years; 33% women) with persPAF and successful CV were enrolled between May 2012 and May 2013. TACT was measured 6 hours after successful CV in the left atrium by tissue Doppler imaging (PA-TDI interval). ERAF was determined via Holter-electrocardiogram over a period of 7 days after CV. Receiver opearting characteristic analysis was used to determine an optimal cutoff value of PA-TDI interval for prognosis of ERAF. Based on this result, recurrence-free survival was assessed with Mantel-Haenszel's log-rank test. ERAF occurred in 23 patients (43%). PA-TDI interval was longer in patients with ERAF compared to those who maintained sinus rhythm (mean ± SD: 163.5 ± 11.1 vs 132.3 ± 11.2 milliseconds; P < 0.00001). At the cutoff value of 152 milliseconds, PA-TDI interval sensitivity and specificity related to ERAF were 87% and 100%, respectively. CONCLUSION: Measuring PA-TDI interval may help to predict ERAF after successful CV in patients with persAF.

B-type natriuretic peptide is a strong independent predictor of long-term outcome after transcatheter aortic valve implantation.

BACKGROUND AND AIM OF THE STUDY: The aim of this prospective study was to determine the impact of plasma B-type natriuretic peptide (BNP) on long-term outcome in patients undergoing transcatheter aortic valve implantation (TAVI). METHODS: TAVI was performed either transfemorally or transaxillary using either the CoreValve prosthesis or Edwards SAPIEN prosthesis in 226 patients with symptomatic severe aortic valve stenosis and at high surgical risk. The examinations included measurements of plasma BNP and echocardiography before and at 30 days after TAVI. The primary study end-point was death from any cause after TAVI; the secondary end-point was defined as cardiovascular death. RESULTS: During a mean follow up of 728 ± 549 days, 72 patients died; 52 deaths were cardiovascular-related. Those patients who died had higher preprocedural plasma BNP levels compared to those who survived (1,305 ± 1,238 pg/ml versus 716 ± 954 pg/ml; p < 0.001). Plasma BNP was the strongest independent predictor of all-cause mortality (BNP > 475 pg/ml, hazard risk [HR] 3.049; 95% confidence interval [CI] 1.804-5.151; p < 0.001) and cardiovascular mortality (BNP > 475 pg/ml, HR 3.479; 95% CI 1.817-6.662; p < 0.001). In surviving patients, plasma BNP levels were decreased by 30 days after TAVI (pre-TAVI 874 ± 1,122 pg/ml; post TAVI 471 ± 569 pg/ml; p < 0.001). A plasma BNP level > 328 pg/ml at 30 days postoperatively was also associated with all-cause mortality (HR 8.125; 95% CI 3.097-21.318; p < 0.001). CONCLUSION: In patients undergoing TAVI, plasma BNP is the strongest independent predictor of all-cause mortality and cardiovascular mortality. Plasma BNP levels at 30 days after TAVI may provide prognostic information that should, potentially, lead to a more intensive therapy of these patients.

Increased preoperative serum apoptosis marker fas ligand correlates with histopathology and new-onset of atrial fibrillation in patients after cardiac surgery.

BACKGROUND: We evaluated if preoperative serum apoptosis markers correlate with atrial histological remodeling and postoperative atrial fibrillation (POAF) after cardiac surgery. METHODS AND RESULTS: A total of 33 patients with sinus rhythm (SR) and without history of atrial fibrillation (AF) undergoing cardiac surgery were prospectively enrolled. Serum concentrations of Fas (apoptosis-stimulating fragment ligand) and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) were measured preoperatively. Right atrial appendage (RAA) tissue was obtained during surgery. Atrial apoptosis was assessed via TUNEL assay and degree of atrial fibrosis was categorized histologically by visual quantification. Continuous ECG-Monitoring was used to screen for POAF throughout 10 days after cardiac surgery. POAF occurred in 15 patients (45%). Atrial apoptosis was higher in patients with POAF as compared to those without (35.9 ± 9.8% vs 14.5 ± 7.5%; P < 0.0001) and correlated with the degree of atrial fibrosis (r = 0.69; P < 0.0001). In contrast to TRAIL (87.0 ± 8.2 pg/mL vs 83.3 ± 9.4 pg/mL; P = 0.77), preoperative Fas serum concentration was significantly higher in patients with POAF compared to patients in stable SR (91.3 ± 7.2 pg/mL vs 66.7 ± 3.0 pg/mL; P < 0.01). Serum Fas concentration correlated with the degree of atrial apoptosis (r = 0.63; P < 0.001) and the degree of atrial fibrosis (r = 0.39; P < 0.05). CONCLUSION: Preoperative evaluation of serum apoptosis marker Fas is useful to identify patients at risk for POAF undergoing cardiac surgery. Fas but not TRAIL correlates with the documented degree of atrial apoptosis and atrial fibrosis in RAA tissue. Further studies need to identify the prospective role of Fas in predicting POAF events.

Correlation between total atrial conduction time estimated via tissue Doppler imaging (PA-TDI Interval), structural atrial remodeling and new-onset of atrial fibrillation after cardiac surgery.

BACKGROUND: Recent studies identified total atrial conduction time (TACT) as an independent and powerful predictor of new-onset atrial fibrillation (AF). The purpose of this study was to assess the association between the degree of atrial fibrosis, TACT, and frequency of postoperative atrial fibrillation (POAF) among patients undergoing cardiac surgery. METHODS AND RESULTS: Sixty patients in sinus rhythm (mean ± SD age 66 ± 10 years; 22% women) and without a history of AF undergoing cardiac surgery were prospectively enrolled. TACT was measured preoperatively in the left atrium by tissue-Doppler Imaging (PA-TDI interval). Holter-ECG/telemetry was used to screen for POAF throughout 10 days after cardiac surgery. Right atrial appendages (RAA) were obtained in 33 patients during surgery; atrial fibrosis was assessed by visual quantification (% area of positive van Gieson elastic staining). POAF occurred in 23 patients (38%). Fibrosis extent of RAA was higher in patients with POAF as compared to those without (27.5 ± 1.93 vs 15.8 ± 0.81% area; mean ± SEM; P < 0.001). PA-TDI interval was longer in patients with POAF versus patients who maintained in sinus rhythm (152.1 ± 3.0 vs 120.8 ± 1.8 milliseconds; P < 0.001) and correlated with the degree of atrial fibrosis (r = 0.73; P < 0.01). At the cut-off value of 133 milliseconds, TACT sensitivity and specificity related to POAF were 100% and 86%, respectively. CONCLUSION: PA-TDI interval is useful to identify patients at risk for POAF undergoing cardiac surgery and correlates with the degree of atrial fibrosis.

Catheter ablation of electrical storm.

Electrical storm (ES) is defined as the occurrence of ≥ three distinct episodes of ventricular arrhythmia (VA) in patients with implanted defibrillators within 24 h. Whereas conventional strategies for acute rhythm stabilization may be effective in some patients the occurrence of ES impairs survival and predicts recurrent VA. Catheter ablation in the setting of ES is complex and involves decisive strategies for individualized ablation approaches adapted to the patient's cardiac abnormalities. Success rates have been documented to be between 79 and 94% in larger studies and effective ablation improves survival and freedom from any VA. Ablation should be considered early in the treatment plan and availability may be improved by interhospital collaboration with highly experienced VA intervention centers.

Shift in the pattern of autonomic atrial innervation in subjects with persistent atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is a multifactorial disease of the atria. OBJECTIVE: We studied the differences in the atrial autonomic innervation pattern in subjects with AF compared with sinus rhythm (SR). METHODS: Preparation of postmortem isolated hearts of subjects with documented persistent AF (group A) and SR (group B) included: (1) histological sectioning of predefined areas and quantification of nerve density, and (2) differentiation using immunohistochemistry in adrenergic (sympathetic, tyrosine-hydroxylase antibody), cholinergic (parasympathetic, choline-acetyltransferase antibody) and mixed (adrenergic and cholinergic staining) nerves. RESULTS: Characteristics of subjects in group A (N = 15) and group B (N = 24) did not differ. The mean overall nerve density was similar between groups (A: 0.31 ± 0.25/mm(2); B: 0.35 ± 0.25/mm(2); P = .87). Nerve density appeared higher in the region of the pulmonary vein ostia and antrum (group A: 0.38 ± 0.21/mm(2); group B: 0.32 ± 0.19/mm(2),) compared with other locations of the right and left atrium. A total of 2,224 (group A: 685; group B: 1539) nerves were differentiated using immunohistochemistry. There was a high degree of colocalization of adrenergic and cholinergic nerves (group A: 80% mixed staining, group B: 69% mixed staining). In group A hearts there was a significantly lower density of predominantly cholinergic nerves (0.025 ± 0.052/mm(2) vs. 0.058 ± 0.099/mm(2); P = .008) and a higher density of nerves containing adrenergic components (0.24 ± 0.18/mm(2) vs. 0.18 ± 0.17/mm(2), P = .046). CONCLUSION: Overall autonomic nerve density did not differ between atria with persistent AF compared with SR. On a morphological level, we detected a shift toward a lower density of cholinergic nerves and a higher density of nerves containing adrenergic components in AF subjects.

Catheter ablation of electrical storm in a collaborative hospital network.

An electrical storm (ES) is defined as multiple ventricular arrhythmia episodes leading to implantable cardioverter defibrillator interventions. Although conventional rhythm stabilization might be of help acutely, ES involves high mortality and morbidity. We evaluated the effect of catheter ablation strategies in the setting of an interhospital collaborative network on the recurrence of ventricular arrhythmia episodes and mortality in patients with ES. Consecutive patients presenting for invasive treatment of ES from December 2007 to December 2009 were included. All patients underwent catheter ablation of ventricular arrhythmia. The strategies were adapted to the individual cardiac pathologic features. The follow-up examination constituted periodic implantable cardioverter defibrillator interrogation. A total of 32 patients were included. Of the 32 patients, 29 (91%) had monomorphic ventricular tachycardia and 3 ventricular fibrillation. The mean number of implantable cardioverter defibrillator-treated episodes within 7 days before ablation was 16 ± 11. Of the 32 patients, 27 underwent ablation within 24 hours after admission, and 5 underwent acute ablation within 8 hours. In 3 patients, epicardial ablation was performed. In all but 2 patients (6%), the clinical arrhythmia was successfully ablated. During a median follow-up of 15 months, 10 patients (31%) had recurrences of sustained ventricular arrhythmia, including 2 patients (6%) with recurrent ES. Three patients (9%) died during the follow-up period. In conclusion, catheter ablation effectively suppressed ventricular arrhythmia midterm recurrences in patients presenting with ES. Catheter ablation is complex in these severely sick patients. The recurrence rate of ventricular arrhythmia appears to be 31% and the mortality rate to be 9%. Collaborative hospital networks to increase the prompt availability of ES ablation might help to optimize the ES outcome.

One-year results of transcatheter aortic valve implantation in severe symptomatic aortic valve stenosis.

Transcatheter aortic valve implantation (TAVI) is an alternative therapy for symptomatic severe aortic valve stenosis in high-risk patients with several co-morbidities. We evaluated the 1-year effects of TAVI on quality of life, exercise capacity, neurohormonal activation, and myocardial hypertrophy. From June 2008 to October 2009, consecutive patients aged ≥75 years with symptomatic severe aortic valve stenosis (area <1 cm(2)) and a logistic euroSCORE ≥15% or aged >60 years with additional specified risk factors underwent TAVI. An aortic valve prosthesis (CoreValve) was inserted in a retrograde fashion. Examinations were performed before and 30 days and 1 year after TAVI. An assessment of the quality of life (Minnesota Living with Heart Failure Questionnaire), a 6-minute walking test, measurement of B-type natriuretic peptide, and echocardiography were performed. In 51 patients (mean age 78 ± 6.6 years, mean left ventricular ejection fraction 58.4 ± 12.2%), the follow-up examinations were performed after TAVI. The 1-year follow-up visit after TAVI revealed significantly improved quality of life (baseline Minnesota Living with Heart Failure Questionnaire score 39.6 ± 19 vs 26.1 ± 18, p <0.001) and more distance covered in the 6-minute walking test (baseline 185 ± 106 vs 266 ± 118 m, p <0.001). The B-type natriuretic peptide level had decreased (baseline 642 ± 634 vs 323 ± 266 pg/ml, p <0.001), and the left ventricular mass index had decreased (156 ± 45 vs 130 ± 42 g/m(2), p <0.001). The left ventricular diameter and ejection fraction remained unchanged. In conclusion, TAVI leads to significantly reduced neurohormonal activation, regression of myocardial hypertrophy, and lasting enhancement of quality of life and exercise capacity in patients with symptomatic and severe aortic stenosis 1 year after intervention.

Termination of ventricular tachycardia by far-field stimulation in humans: a feasibility study.

BACKGROUND: Although a low-energy cardioversion (LEC) shock from an implantable cardioverter-defibrillator (ICD) can terminate ventricular tachycardia (VT), it frequently triggers ventricular fibrillation (VF) and is therefore not used in clinical practice. We tested whether a modified LEC shock with a very short duration (0.12-0.36 ms), termed "field stimulus," can terminate VT without triggering VF. METHODS: In 13 sedated patients with implanted ICDs, we attempted to induce VT and to terminate the arrhythmias by field stimuli during hospital predischarge tests. RESULTS: In eight patients, 27 VT episodes were induced and treated with a total of 46 high-voltage (25-200 V) field stimuli, which terminated 11 VT episodes (41% efficacy) and never accelerated VT into VF. VT episodes slower than 230 beats per minute (bpm) (median rate) were terminated more successfully than faster arrhythmia episodes (69% vs 15%, P < 0.01). The strength of the field stimulus had no major influence on the effectiveness. We therefore postulate that suboptimal timing of field stimuli (delivered simultaneously with a sensed event in the right ventricular apex) was the main reason for failed VT terminations. CONCLUSION: A short (0.12-0.36 ms), high-voltage (50-100 V) field stimulus delivered from the shock coil of an implanted ICD system can safely terminate VT, especially for VT rates below 230 bpm. We believe that it would be reasonable to test the effectiveness of automatic field-stimulus therapy from implanted ICDs in VT episodes up to 230 bpm that are not susceptible to termination by antitachycardia pacing.

Usefulness of a limited linear ablation of post-myocardial infarction ventricular tachycardia using a standardized approach based on sinus rhythm mapping.

The ablation of ventricular tachycardia (VT) can be achieved using anatomically guided approaches using differentiated mapping and ablation techniques. The aim of this study was to evaluate the efficacy of limited linear ablation in the VT exit region identified during sinus rhythm mapping alone. One hundred fifteen consecutive patients presenting for ablation of post-myocardial infarction VT were included. After induction of the target VT during invasive electrophysiology, left ventricular substrate mapping during sinus rhythm to identify scar and border zone on the basis of endocardial bipolar voltage was performed. The exit site of the target VT was regionalized by a simplified vector pace mapping approach and targeted using limited linear ablation within the scar border zone. Seventy-seven percent of all inducible VT was successfully ablated. In 71 patients (62%), no sustained VT was inducible at the end of ablation procedure (complete success). During a median follow-up period of 16 + or - 10 months, 89 patients (77%) had no documented sustained ventricular arrhythmia. Seven patients (2%) had recurrences of the initially ablated VT, and 16 (14%) had new-onset VT. Patients with complete success had a significantly lower number of ventricular arrhythmia reoccurrences than patients with incomplete ablation success (11% vs 37%, p = 0.002). In conclusion, postinfarct VT was effectively ablated in 97% of patients without mapping during ongoing VT using a simplified regional linear ablation approach targeting the scar border zone. Freedom from any ventricular arrhythmia was achieved in 77% of patients during midterm follow-up.

Long-term sinus rhythm stability after intraoperative ablation of permanent atrial fibrillation.

INTRODUCTION: Short- and medium-term sinus rhythm (SR) rates after intraoperative radiofrequency ablation to treat permanent atrial fibrillation (AF) are well documented. Is rhythm success stable during a long-term follow-up? METHODS AND RESULTS: A total of 130 patients who had undergone intraoperative radiofrequency cooled-tip endocardial ablation (SICTRA) of permanent AF (mean AF duration 6+/-5 years) concomitant to open heart surgery more than 3 years ago were followed up using electrocardiogram (ECG), Holter-ECG, and echocardiography and compared with 12-month follow-up data. In 55% of patients, only the left atrium and in 45%, both atria were treated using SICTRA. Mitral valve replacement was performed in 21, mitral valve reconstruction in 25, aortic valve replacement in 13, CABG procedures in 51 (including 11 patients with additional mitral valve surgery), and complex procedures in 20 patients. Sixty-nine percent of patients (90/130) were in stable SR after a median period of 48 months, whereas 28% (36/130) were in AF and 3% (4/130) were in atrial flutter. In between the 12-month follow-up and the long-term follow-up, seven patients converted to AF after having documented SR, two patients converted to typical right atrial flutter after being in SR, and two patients from AF to left atrial macroreentry. After left and biatrial SICTRA, SR rates were comparable (73% vs 66%, P = 0.45). Echocardiography revealed 73% of patients in SR to have effective left atrial contraction. CONCLUSIONS: SICTRA restores long-term stable SR in 69% of all patients. Nine percent of patients reconverted back to atrial arrhythmia after having documented SR at 12 months.

G protein-activated (GIRK) current in rat ventricular myocytes is masked by constitutive inward rectifier current (I(K1)).

Inwardly-rectifying K+ channel subunits are not homogenously expressed in different cardiac tissues. In ventricular myocytes (VM) the background current-voltage relation is dominated by I(K1), carried by channels composed of Kir2.x subunits, which is less important in atrial myocytes (AM). On the other hand in AM a large G protein gated current carried by Kir3.1/3.4 complexes can be activated by stimulation of muscarinic M(2) receptors (I(K(ACh))), which is assumed to be marginal in VM. Recent evidence suggests that total current carried by cardiac inward-rectifiers (I(K(ATP)), I(K(ACh)), I(K1)) in both, AM and VM is limited, due to K+ accumulation/depletion. This lead us to hypothesize that in conventional whole celI recordings I(K(ACh)) in VM is underestimated as a consequence of constitutive I(K1). In that case a reduction in density of I(K1) should be paralleled by an increase in density of I(K(ACh)). Three different experimental strategies have been used to test for this hypothesis: (i) Adenovirus-driven expression of a dominant-negative mutant of Kir2.1, one of the subunits supposed to form I(K1) channels, in VM caused a reduction in I(K1)-density by about 80 %. In those cells I(K(ACh)) was increased about 4 fold. (ii) A comparable increase in I(K(ACh)) was observed upon reduction of I(K1) caused by adenovirus-mediated RNA interference.(iii) Ba2+ in a concentration of 2 microM blocks I(K1) in VM by about 60 % without affecting atrial I(K(ACh)). The reduction in I(K1) by 2 microM Ba2+ is paralleled by a reversible increase in I(K(ACh)) by about 100%. These data demonstrate that the increase in K+ conductance underlying ventricular I(K(ACh)) is largely underestimated, suggesting that it might be of greater physiological relevance than previously thought.

Intra-operative cooled-tip radiofrequency linear atrial ablation to treat permanent atrial fibrillation.

AIMS: To demonstrate the safety and efficacy of saline irrigated cooled-tip atrial linear endocardial radiofrequency ablation (SICTRA) concomitant to open-heart surgical procedures in the treatment of permanent atrial fibrillation (AF). METHODS AND RESULTS: Two hundred and twenty-two patients presenting with permanent AF and the need for cardiac surgery were included. In addition to the cardio-surgical procedure [mitral valve (MV) surgery (n = 94), aortic valve replacement (n = 29), bypass surgery (n = 76 including 24 patients with additional MV surgery), and combined procedures (n = 23)] concomitant SICTRA was performed. In 116 patients, the ablation pattern was restricted to the left atrium alone. During the mean follow-up of 29 months, 174 patients (78%) converted to sinusrhythm (SR). In patients with SICTRA restricted to the left atrium conversion rates were not different compared to a biatrial approach (83 vs. 74%, P = 0.47). Thirty-days mortality was found to be 4% (9/222). Post-mortem evaluation revealed 23% of all lesions to be histologically non-transmural. In the overall group, only 4% of patients developed sustained secondary regular atrial arrhythmia. CONCLUSIONS: SICTRA safely and effectively restores stable SR in 78% of patients with permanent AF undergoing open-heart surgery. Rhythm outcome is not influenced by treatment of the right atrium. Sustained regular atrial arrhythmia with the need for invasive treatment strategies occurs in 4% although intra-operative ablation lesions are often non-transmural.