Automation in flow cytometry: Guidelines and review of systems.

Automation in flow cytometry has recently advanced from the partial laboratory automation and robotics islets, to more fully integrated systems. This article reviews three manufacturers' newest sample preparation systems: the Beckman CellMek, the Sysmex PS-10, and the BD FACSDuet. These three instruments are capable of performing many of the manual steps in flow cytometry sample processing (pipetting, staining, lysing, washing, fixing). General description, capabilities, advantages, and disadvantages of each system are compared. Overall, these systems have the potential to become mainstay items in today's busy clinical flow cytometry laboratories, and save a significant amount of hands-on time for laboratory staff.

Impact of the COVID-19 lockdown in urgent pacemaker implantations: A cross-sectional study.

AIMS: The COVID-19 pandemic resulted in a decrease in patients' follow-up and interventions with cardiovascular disease. In Portugal, the consequences on emergent pacemaker implantation rates are largely unknown. We sought to analyze the impact of the COVID-19 pandemic on emergent pacemaker implantation rate and patient profile. METHODS: We retrospectively reviewed the clinical profile of the 180 patients who had pacemakers implanted in our hospital in an emergent setting from March 18, 2020, to May 17, 2020 ("lockdown") and May 19 to July 17, 2020 ("postlockdown"). This data was then directly compared to the homologous periods from the year before. RESULTS: Urgent pacemaker implantation rates during "lockdown" was lower than its homologous period (-23.7%), and cases in "postlockdown" were significantly increased (+106.9% vs. "lockdown"; +13.2% vs. May-July 2019).When comparing "lockdown" and "postlockdown," there was a tendency for a higher number of temporary pacemaker use (p = .076). Patients during "lockdown" were 7.57 times more likely to present with hypotension/shock (odds ratio 7.57; p = .013). We also noted a higher tendency for hypotension on presentation during "lockdown" (p = .054) in comparison to 2019. In comparison to its homologous 2019 period, "postlockdown" saw more patients presenting with bradycardia (p = .026). No patients were admitted to the emergency department during "lockdown" for anomalies detected on ambulatory tests. CONCLUSION: Our data show that the COVID-19 pandemic had a real impact on urgent pacemaker implantation. Patients with bradyarrhythmias are at particular risk for severe complications and should seek medical care regardless of the pandemic.

Digoxin in Patients With Advanced Heart Failure and Sinus Rhythm Submitted to Cardiac Resynchronization Therapy-Is There Any Benefit?

ABSTRACT: Digoxin (DG) use in patients with heart failure with reduced ejection fraction (HFrEF) and sinus rhythm remains controversial. We aimed to assess the prognostic effect of DG in patients in sinus rhythm submitted to cardiac resynchronization therapy (CRT). Retrospective study including 297 consecutive patients in sinus rhythm, with advanced HFrEF submitted to CRT. Patients were divided into 2 groups: with DG and without DG (NDG). During a mean follow-up of 4.9 ± 3.4 years, we evaluated the effect of DG on the composite end point defined as cardiovascular hospitalization, progression to heart transplantation, and all-cause mortality. Previous to CRT, 104 patients (35%) chronically underwent DG and 193 patients (65%) underwent NDG treatment. The 2 groups did not differ significantly regarding HF functional class, HF etiology, QRS, and baseline left ventricular ejection fraction. The proportion of responders to CRT was similar in both groups (54% in DG vs. 56% in NDG; P = 0.78). During the long-term follow-up period, the primary end point occurred in a higher proportion in DG patients (67 vs. 48%; P = 0.002). After adjustment for potential confounders, DG use remained as an independent predictor of the composite end point of CV hospitalization, heart transplantation, and all-cause mortality [hazards ratio = 1.58; confidence interval, 95 (1.01-2.46); P = 0.045]. In conclusion, in patients in sinus rhythm with HFrEF submitted to CRT, DG use was associated with CV hospitalization, progression to heart transplant, and all-cause mortality.

Hip Arthroscopy and Core Decompression for Avascular Necrosis of the Femoral Head Using a Specific Aiming Guide: A Step-by-Step Surgical Technique.

Avascular necrosis of the femoral (AVN) head is a disabling disease that affects function, mobility, and quality of life in the young adult. Its pathology involves blood circulation disruption of the femoral head and subchondral infarction. This leads to cartilage thinning, femoral head depression, and cartilage breakage, which results in hip osteoarthritis. In the past decade the prevalence of intraarticular pathology has been almost 95%, this revealed with hip arthroscopy (HA). HA and core decompression (CD) of the femoral head can be used effectively and concomitantly to treat AVN with excellent results, HA allows for excellent visualization of the hip joint cartilage, allowing treatment of femoroacetabular impingement syndrome (FAIS) and intra-articular pathology. Our technique demonstrates that retrograde core decompression with allograft and mixed bone matrix is an excellent choice of treatment in the early stages of AVN/ONFH. The femoral head-specific aiming guide is very reliable, is simple to use arthroscopically if placed in the posterolateral portal of the hip, and offers exact pin placement at the necrotic site, as well as less operative time and less radiation to the patient and surgical team.

The Outside-In Technique for Slipped Capital Femoral Epiphysis: A Safe and Reproducible Approach in Hip Arthroscopy.

Femoroacetabular impingement syndrome caused by slipped capital femoral epiphysis (SCFE) can be successfully treated arthroscopically and with the minimally invasive, outside-in surgical technique. The advantages of the technique are that the residual cam-type deformity caused by the slippage can be corrected and reconstructed reliably and reproducibly before distracting the hip joint; and radiation with fluoroscopy is used for only definitive reduction and reconstruction, which is obtained with cannulated screws. In addition, this safe technique allows distraction of the hip after screw placement, without affecting the reconstruction, to address labral tears and chondrolabral delaminations caused by the impingement.

Improvement in circulating endothelial progenitor cells pool after cardiac resynchronization therapy: increasing the list of benefits.

BACKGROUND: Recent studies suggest that circulating endothelial progenitor cells (EPCs) may influence the response to cardiac resynchronization therapy (CRT). The aim of this study was to evaluate the effect of CRT on EPC levels and to assess the impact of EPCs on long-term clinical outcomes. POPULATION AND METHODS: Prospective study of 50 patients submitted to CRT. Two populations of circulating EPCs were quantified previously to CRT implantation: CD34+KDR+ and CD133+KDR+ cells. EPC levels were reassessed 6 months after CRT. Endpoints during the long-term follow-up were all-cause mortality, heart transplantation, and hospitalization for heart failure (HF) management. RESULTS: The proportion of non-responders to CRT was 42% and tended to be higher in patients with an ischemic vs non-ischemic etiology (64% vs 35%, p = 0.098). Patients with ischemic cardiomyopathy (ICM) showed significantly lower CD34+KDR+ EPC levels when compared to non-ischemic dilated cardiomyopathy patients (DCM) (0.0010 ± 0.0007 vs 0.0030 ± 0.0024 cells/100 leukocytes, p = 0.032). There were no significant differences in baseline EPC levels between survivors and non-survivors nor between patients who were rehospitalized for HF management during follow-up or not. At 6-month follow-up, circulating EPC levels were significantly higher than baseline levels (0.0024 ± 0.0023 vs 0.0047 ± 0.0041 CD34+KDR+ cells/100 leukocytes, p = 0.010 and 0.0007 ± 0.0004 vs 0.0016 vs 0.0013 CD133+/KDR+ cells/100 leukocytes, p = 0.007). CONCLUSIONS: Patients with ICM showed significantly lower levels of circulating EPCs when compared to their counterparts. CRT seems to improve the pool of endogenously circulating EPCs and reduced baseline EPC levels seem not to influence long-term outcomes after CRT.

Pacemaker implantation in familial amyloid polyneuropathy: when and for whom?

BACKGROUND: Despite the important role of cardiac pacing in preventing syncope and sudden cardiac death in familial amyloid polyneuropathy (FAP), we lack clear guidelines as to the ideal timing and indications for permanent pacemaker implantation. PURPOSE: The purpose of this study was to evaluate the ideal timing for pacemaker implantation in FAP patients submitted to liver transplantation. METHODS: Retrospective study of 258 FAP patients submitted to liver transplantation between 1992 and 2012. Comparison of three groups: (A) patients without pacemaker (N = 122); (B) patients submitted to pacemaker implantation after liver transplantation, with documented conduction disorders (N = 73); and (C) patients submitted to "prophylactic" pacemaker implantation before transplantation, (N = 73). Patients were followed up for 12.2 ± 6.7 years. RESULTS: The majority of patients (57%) were referred for pacemaker implantation, which occurred before liver transplantation in 50% of cases. Patients who required pacemaker after transplantation presented significantly higher Machado-Joseph Score during pre-transplant evaluation than those who did not require pacemaker (24 ± 10 vs 20 ± 10, p = .025), and also exhibited higher levels of hepatic cytolysis enzymes and hyperbilirubinemia. The most common indication for permanent pacemaker was first degree atrioventricular block, with a mean time between transplantation and pacemaker implantation of 8.7 ± 4.2 years. During long-term follow-up, all-cause mortality was 27% and was lowest in the group submitted to pacemaker implantation only after liver transplantation (p = 0.002). CONCLUSION: The majority of FAP patients submitted to liver transplantation will need a pacemaker at some time of follow-up. However, it seems that there is no benefit in "prophylactic" cardiac pacing before liver transplantation.

Unsafe Drug Use and Arrhythmic Events in Brugada Patients with ICD: Results of a Long-Term Follow-Up.

PURPOSE: Brugada syndrome is a hereditary disease linked with an increased risk of sudden death that may require an implantable cardioverter-defibrillator (ICD) in order to halt the arrhythmic events. The aim of this study was to identify possible triggers for appropriate ICD therapies in patients with Brugada syndrome, focusing on their past and current therapeutic profiles. METHODS: Thirty patients with high-risk Brugada syndrome, with ICD implanted at the Coimbra Hospital and University Center, were enrolled. Patients were questioned about their Brugada syndrome history, previous cardiac events, comorbidities, present and past medications, and physical activity. Patients were followed up during 5.8 ± 5.3 years. The ICD was interrogated, and arrhythmic events and device therapies were recorded. The cohort who received appropriate ICD therapies was compared with the remaining patients to determine the potential link between clinical variables and potentially fatal arrhythmic events. RESULTS: More than half of the patients (53.3%) took at least one non-recommended drug, and 16.7% received appropriate ICD therapies, with a long-term rate of 4.0%/year. There was a tendency for more appropriate ICD therapies in patients who took unsafe drugs (85.7 versus 45.5%, p = 0.062), and the mean time between unsafe drug intake and appropriate ICD therapies was 3.8 ± 7.5 days. CONCLUSIONS: This study revealed that the medical community is still unaware of the pharmacological restrictions imposed by Brugada syndrome. Patients who took non-recommended drugs seem to have a higher risk of ventricular arrhythmic events.

Who still remains at risk of arrhythmic death at time of implantable cardioverter-defibrillator generator replacement?

BACKGROUND: Implantable cardioverter-defibrillator (ICD) is associated with reduction in arrhythmic mortality. However, at the time of generator replacement (GR) some patients had not experienced therapies and had a different clinical profile. Therefore, the risk-benefit ratio of ICD may have changed. Our aim was to determine the proportion of patients with ICD implanted in primary prevention that maintain guideline-derived indications at the time of GR and assess predictors of therapies in the postreplacement period. We evaluate the long-term benefit of ICD after GR in nonischemic cardiomyopathy (NICM) versus ischemic cardiomyopathy (ICM). METHODS: We included 141 patients undergoing GR from 11/2009 to 7/2015. Patients were divided into: G1 - guideline congruent indication for ICD at the time of GR (left ventricular ejection fraction [LVEF] ≤ 35% or appropriate therapies) and G2 - guideline incongruent indication (patients without appropriate therapies and LVEF >35%). We also compared ICD benefit between ICM and NICM patients. RESULTS: Maintenance of guideline-driven indications for ICD (G1) was present in 68% of patients and 32% had recovery of LVEF and no ICD therapies at the time of GR (G2). After GR, G2 patients showed a lower rate of appropriate therapies (3% vs 33%, P < 0.01). LVEF ≤ 35% was the only independent predictor of appropriate therapies (OR 12.0, P < 0.01). In multivariate analysis, etiology of heart failure did not predict the arrhythmic risk. CONCLUSION: At the time of GR, a significant proportion of patients no longer met guideline indications for ICD and their need for therapies is reduced. The etiology of heart failure did not predict freedom from therapies.

Initial international multicenter human experience with a novel epicardial access needle embedded with a real-time pressure/frequency monitoring to facilitate epicardial access: Feasibility and safety.

BACKGROUND: Epicardial ablation is often necessary for the treatment of complex arrhythmias refractory to endocardial ablation. Conventional needle access to the pericardial space is considered quite challenging, and it is often associated with several potential complications, particularly inadvertent right ventricular puncture. The novel EpiAccess needle tip is embedded with a pressure sensor able to report the pressure waveform in real time when used with the EpiAccess System. OBJECTIVE: We prospectively evaluated the feasibility and safety of the EpiAccess System by EpiEP, Inc., with a novel epicardial access needle in a multicenter study. METHODS: Twenty-five patients with a clinical need for epicardial access were enrolled. The EpiAccess needle and EpiAccess System were used for epicardial access in each case. Successful epicardial access, defined as the ability to introduce a guidewire into the epicardial space, was assessed via the device and confirmed with fluoroscopy. Significant pericardial bleeding was defined as >80 mL of blood by using peer review article definitions. RESULTS: Patients were men (76%) with a mean age of 62 years (range 28-84 years). Epicardial access for ventricular tachycardia ablation was indicated in 80% of the patients. Successful epicardial access was obtained in all cases, with pressure monitoring guiding pericardial wire access in all cases. One delayed pericardial effusion occurred. CONCLUSION: Epicardial access with the novel EpiAccess needle and System with real-time pressure monitoring is feasible and safe. The pressure monitoring capability identifies successfully the epicardial space, facilitating access and potentially minimizing complications. This has relevant clinical implications.

Transvenous removal of cardiac implantable electronic device leads.

INTRODUCTION AND OBJECTIVE: The number and complexity of cardiac implantable electronic devices (CIEDs) have increased, as has the number of related complications, often leading to removal of the implanted system. The aim of this study was to characterize transvenous explantation/extraction of CIED leads in a reference center. METHODS: This was a descriptive observational study of patients consecutively admitted from January 2009 to May 2014 for transvenous lead extraction. RESULTS: The sample consisted of 109 patients, with a mean age of 64.6±16.62 years, 73.1% male. The main indication for lead extraction was CIED infection. The mean time from first implantation to lead removal was 5.6±4.89 years. Blood cultures were positive in 32.8% of cases and 29% of patients had vegetations on echocardiography. A total of 228 cardiac leads were removed, of which 58.8% were ventricular, 32.4% atrial and 8.8% coronary sinus. Complete clinical success was achieved in 97.2% of cases, while procedural success was complete in 93.4% and partial in 5.3%. The complications reported were three cases of significant pocket hematoma, one of subclavian vein thrombosis and three of cardiac tamponade, effectively treated by pericardiocentesis. CONCLUSIONS: Transvenous explantion or extraction of CIED leads was highly effective. A high level of experience is an essential factor in the success and safety of the procedure.

Circulating endothelial progenitor cells as a predictor of response to cardiac resynchronization therapy: the missing piece of the puzzle?

BACKGROUND: It would be important to better identify heart failure (HF) patients most likely to respond to cardiac resynchronization therapy (CRT). Because endothelial progenitor cells (EPCs) play a crucial role in the maintenance of vascular endothelium integrity, we hypothesize that patients who have higher circulating EPCs levels have greater neovascularization potential and are more prone to be responders to CRT. METHODS: Prospective study of 30 consecutive patients, scheduled for CRT. Echocardiographic evaluation was performed before implant and 6 months after. Responders to CRT were defined as patients who were still alive, have not been hospitalized for HF management, and demonstrated ≥15% reduction in left ventricular end-systolic volume (LVESV) at the 6-month follow-up. EPCs were quantified before CRT, from peripheral blood, by flow cytometry using five different conjugated antibodies: anti-CD34, anti-KDR, anti-CD133, anti-CD45, and anti-CXCR4. We quantified five different populations of angiogenic cells: CD133(+) /CD34(+) cells, CD133(+) /KDR(+) cells, CD133(+) /CD34(+) /KDR(+) cells, CD45(dim) CD34(+) /KDR(+) cells, and CD45(dim) CD34(+) /KDR(+) /CXCR4(+) cells. RESULTS: The proportion of responders to CRT at the 6-month follow-up was 46.7%. Responders to CRT presented higher baseline EPCs levels than nonresponders (0.0003 ± 0.0006% vs 0.0001 ± 0.0002%, P = 0.04, for CD34(+) /CD133(+) /KDR(+) and 0.0006 ± 0.0005% vs 0.0003 ± 0.0003%, P = 0.009, for CD45(dim) CD34(+) /KDR(+) /CXCR4(+) cells). In addition, baseline levels of CD45(dim) CD34(+) /KDR(+) /CXCR4(+) cells were positively correlated with the reduction of LVESV verified 6 months after CRT (r = 0.497, P = 0.008). CONCLUSIONS: High circulating EPCs levels may identify the subset of HF patients who are more likely to undergo reverse remodeling and benefit from CRT. Addition of EPCs levels assessment to current selection criteria may improve the ability to predict CRT response.

[National registry on cardiac electrophysiology (2010 and 2011)]. / Registo Nacional de Eletrofisiologia Cardíaca (2010 e 2011).

Based on a survey sent to Portuguese centers that perform diagnostic and interventional electrophysiology and/or implant cardioverter-defibrillators (ICDs), the authors analyze the number and type of procedures performed during 2010 and 2011 and compare these data with previous years. In 2011, a total of 2533 diagnostic electrophysiologic procedures were performed, which were followed by ablation in 2013 cases, a steady increase over previous years. The largest share of this increase compared to 2010 was in atrial fibrillation, which is now the second most frequent indication for ablation, after atrioventricular nodal reentrant tachycardia. The total number of ICDs implanted in 2011 was 1084, of which 339 were biventricular (BiV) cardiac resynchronization devices (BiV ICDs). This represents an increase in the total number relative to previous years, 2011 being the first year in which the rate of new ICD implantations in Portugal exceeded 100 per million population. However, compared to 2010, the number of BiV ICDs implanted decreased, despite the recent publication of updated European guidelines on device therapy in heart failure, which clarified and expanded the indications for implantation of these devices. Some comments are made on the current status of cardiac electrophysiology in Portugal and on factors that may influence its development in the coming years.

National Registry on Cardiac Electrophysiology 2009.

The authors analyze the number and type of electrophysiologic procedures (diagnostic and ablation, and implantation of defibrillators and biventricular pacemakers with defibrillator backup) that were performed during 2009 in all Portuguese electrophysiology centers. A total of 2669 diagnostic electrophysiologic procedures were performed during the year, of which 62% were followed by ablation, amounting to 1668 ablations. The authors describe the type of ablations performed by the various centers, and analyze the distribution and type of ablation procedures in the light of recent data from published international studies. A total of 1089 ICDs were implanted during 2009, and the authors also describe the type of devices employed and comment on these data bearing in mind recent published data.

Cardiac resynchronization therapy is effective even in elderly patients with comorbidities.

PURPOSE: The purpose of this study was to compare the effects of cardiac resynchronization therapy (CRT) in elderly patients (> or =65 years) with younger patients and to assess the impact of comorbidities in CRT remodeling response. METHODS: This is a prospective study of 87 consecutive patients scheduled for CRT who underwent clinical and echocardiographic evaluation before and 6 months after CRT. A reduction in left ventricular end-systolic volume (LVESV) > or =15% after CRT defined remodeling responders, and a reduction of at least one New York Heart Association class defined clinical responders. Multivariate analysis was used to identify independent predictors of non-response to CRT in terms of reverse remodeling. RESULTS: The mean age was 62 +/- 11 years, with 36 elderly patients (41%). The baseline QRS duration was 145 +/- 32 ms. After CRT, there were significant and similar improvements of left ventricular (LV) ejection fraction, LVESV, LV dP/dt, and mitral regurgitation jet area (JA) between elderly (> or =65 years) and younger (<65 years) patients. The number of clinical and remodeling responders was comparable, and we found no significant differences in unplanned cardiac hospitalizations at 6 months between groups. Independent predictors of lack of remodeling response to CRT were QRS duration <120 ms, LV diastolic diameter >74 mm, and JA >10 cm(2) before CRT, but not comorbidities. CONCLUSION: This work suggests that being elderly is not an impediment to CRT success even in the presence of comorbidities.

Which echocardiographic definition should be used to define response to cardiac resynchronization therapy?

INTRODUCTION: The definition of response to cardiac resynchronization therapy (CRT) remains controversial, with different criteria being used to define a positive response. The PROSPECT trial recently demonstrated that echocardiography is not sufficiently accurate to identify responders to CRT. However, it is possible that the definition used in this study was not the most appropriate. OBJECTIVE: To compare different echocardiographic definitions of response to CRT with peak oxygen consumption (VO2), in an attempt to identify the best echocardiographic definition. METHODS: Thirty consecutive patients who underwent echocardiography and cardiopulmonary exercise testing (CPET) before and 6 months after CRT were studied. An improvement of > or =1 NYHA class defined clinical responders; a > or =15% decrease in left ventricular end-systolic volume (LVESV) defined remodeling responders; a > or =25% improvement in left ventricular ejection fraction (LVEF) identified responders according to LVEF; a >25% improvement in left ventricular dP/dt defined responders according to dP/dt; and a ?10% improvement in peak VO2 defined CPET responders. RESULTS: There were 47% responders according to the reverse remodeling definition, 60% according to LVEF and 67% according to dP/dt; 77% were clinical responders and 40% CPET responders. The only baseline characteristic that differed between CPET responders and non-responders was the sphericity index (57 +/- 12% vs. 72 +/- 16%, p = 0.019), which showed an inverse correlation with CPET response (r = -0.455, p = 0.011). LVEF response showed the best agreement with CPET response (83% positive and 56% negative concordance). Clinical and echocardiographic responses were often discordant: 48% of clinical responders were non-responders according to reverse remodeling, 35% according to LVEF and 39% according to dP/dt. However, of clinical responders who did not respond on echocardiographic criteria, a positive NYHA response paralleled the CPET definition in 35% of cases. CONCLUSION: The best agreement between echocardiographic definitions of response and CPET was achieved with LVEF. In 35% of cases of discrepancy between clinical and echocardiographic responses, the clinical response paralleled CPET, which implies a benefit of CRT undetected by echocardiography and not a placebo effect.

Identification of 'super-responders' to cardiac resynchronization therapy: the importance of symptom duration and left ventricular geometry.

AIMS: Some patients show such an important clinical improvement and reverse remodelling after cardiac resynchronization therapy (CRT) that anatomy and function approach normal. These patients have been called 'super-responders'. The aim of our study was to identify predictors of becoming a super-responder after CRT. METHODS AND RESULTS: Eighty-seven consecutive patients who underwent CRT were prospectively studied. Before CRT and 6 months after, clinical and echocardiographic evaluation was performed. Patients with a decrease in New York Heart Association functional class >or=1, a two-fold or more increase of left ventricular ejection fraction (LVEF) or a final LVEF >45%, and a decrease in LV end-systolic volume >15% were classified as super-responders. There were 12% super-responders. At baseline, there were no significant differences between super-responders and the other patients, except for the fact that super-responders had significantly smaller mitral regurgitation and LV end-diastolic diameter (LVEDD) and a shorter duration of heart failure symptoms. Mitral regurgitation jet area, LVEDD, and duration of heart failure symptoms were correlated with this super-response. Moreover, an evolution of symptoms for <12 months was an independent predictor of super-response to CRT. CONCLUSION: Patients in earlier phases of the cardiomyopathy, with a less altered ventricular geometry, seem to have a greater probability of becoming super-responders.

Previous therapy with amiodarone increases the recurrence rate in successfully ablated patients with isthmus-dependent atrial flutter.

Ablation of isthmus-dependent atrial flutter in patients previously medicated with antiarrhythmic drugs may cause functional isthmus block during ablation, and subsequent discontinuation of therapy may lead to incomplete isthmus block (and recurrence). This may be particularly important if the drugs previously used have long plasma half-lives (and washout periods). The objective of this study was to evaluate whether the recurrence rate of isthmus-dependent atrial flutter was greater in patients previously medicated with antiarrhythmic drugs and whether there were differences in recurrence rate with different types of antiarrhythmic drugs. During a mean follow-up of 20 +/- 7 months, we observed 57 patients with previous successful ablation of isthmus-dependent atrial flutter. This population of patients was divided into three groups according to the type or absence of previous antiarrhythmic drugs: Group 1--n = 18, patients previously medicated with amiodarone; Group 2--n = 27, patients previously medicated with drugs with short plasma half-lives (propafenone; flecainide; beta-blockers); Group 3--patients without previous antiarrhythmic medication. In all 57 patients bidirectional isthmus block was achieved after the ablation procedure; 8 mm non-irrigated tip catheters were used. During follow-up a recurrence rate of 33% was observed in Group 1 (6 recurrences in 18 patients; p < 0.05 in comparison with Groups 2 and 3); 3.7% in Group 2 (1 in 27 patients) and 0% recurrence rate in Group 3. We conclude that in our study the patients previously medicated with amiodarone had a higher recurrence rate of the arrhythmia compared to patients not previously medicated with antiarrhythmic drugs or medicated with antiarrhythmics with short plasma half-lives.