Early mortality in prophylactic implantable cardioverter-defibrillator recipients: development and validation of a clinical risk score.

AIMS: To reduce sudden cardiac death, implantable cardioverter-defibrillators (ICDs) are indicated in patients with ischaemic and non-ischaemic dilated cardiomyopathy and a left ventricular ejection fraction (LVEF) ≤35%. Current guidelines do not recommend device therapy in patients with a life expectancy <1 year since benefit in these patients is low. In this study, we evaluated the incidence and predictors of early mortality (<1 year after implantation) in a consecutive primary prevention population. METHODS AND RESULTS: Analysis was performed on a prediction and validation cohort. The primary endpoint was all-cause mortality at 1 year. The prediction cohort comprised 861 prophylactic ICD recipients with ischaemic cardiomyopathy or dilated cardiomyopathy from the Academic Medical Center (Amsterdam) and Thorax Center Twente (Enschede). Detailed clinical data were collected. After multivariate analysis, a risk score was developed based on age ≥75 years, LVEF ≤ 20%, history of atrial fibrillation, and estimated glomerular filtration rate (eGFR) ≤30 mL/min/1.73 m(2). Using these predictors, a low (≤1 factor), intermediate (2 factors), and high (≥3 factors) risk group could be identified with 1-year mortality of, respectively, 3.4, 10.9, and 38.9% (P< 0.01). Afterwards, the risk score was validated in 706 primary prevention patients from the Erasmus Medical Center (Rotterdam). One-year mortality was, respectively, 2.5, 13.2, and 46.3% (all P< 0.01). CONCLUSION: A simple risk score based on age, LVEF, eGFR, and atrial fibrillation can identify patients at low, intermediate, and high risk for early mortality after ICD implantation. This may be helpful in the risk assessment of ICD candidates.

Implantable cardioverter-defibrillators in hypertrophic cardiomyopathy: patient outcomes, rate of appropriate and inappropriate interventions, and complications.

BACKGROUND: Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM), but this can be prevented by an implantable cardioverter-defibrillator (ICD). The aim of this study is to evaluate HCM patients with ICDs for primary or secondary prevention of SCD. METHODS: The study population consisted of all HCM patients with an ICD in 2 tertiary referral clinics. End points during follow-up were total and cardiac mortality, appropriate and inappropriate ICD intervention, and device-related complications. Cox-regression analysis was performed to identify predictors of outcome. RESULTS: ICDs were implanted in 134 patients with HCM (mean age 44 ± 17 years, 34% women, 4.2 ± 4.8 years follow-up). Annualized cardiac mortality rate was 3.4% per year and associated with New York Heart Association class III or IV (HR 5.2 [2.0-14, P = .002]) and cardiac resynchronization therapy (HR 6.3 [2.1-20, P = .02]). Appropriate ICD interventions occurred in 38 patients (6.8%/year) and was associated with implantation for secondary prevention of SCD (HR 4.0 [1.8-9.1], P = .001) and male gender (HR 3.3 [1.2-9.0], P = .02). Inappropriate ICD intervention occurred in 21 patients (3.7%/year) and in 20 patients device related complications were documented (3.6%/year). CONCLUSION: ICDs successfully abort life-threatening arrhythmias in HCM patients at increased risk of SCD with an annualized intervention rate of 6.8% per year. End-stage heart failure is the main cause of mortality in these patients. The annualized rate of inappropriate ICD intervention was 3.7% per year, whereas device-related complications occurred 3.6% per year.

Rationale and design of the PRAETORIAN trial: a Prospective, RAndomizEd comparison of subcuTaneOus and tRansvenous ImplANtable cardioverter-defibrillator therapy.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are widely used to prevent fatal outcomes associated with life-threatening arrhythmic episodes in a variety of cardiac diseases. These ICDs rely on transvenous leads for cardiac sensing and defibrillation. A new entirely subcutaneous ICD overcomes problems associated with transvenous leads. However, the role of the subcutaneous ICD as an adjunctive or primary therapy in patients at risk for sudden cardiac death is unclear. STUDY DESIGN: The PRAETORIAN trial is an investigator-initiated, randomized, controlled, multicenter, prospective 2-arm trial that outlines the advantages and disadvantages of the subcutaneous ICD. Patients with a class I or IIa indication for ICD therapy without an indication for bradypacing or tachypacing are included. A total of 700 patients are randomized to either the subcutaneous or transvenous ICD (1:1). The study is powered to claim noninferiority of the subcutaneous ICD with respect to the composite primary endpoint of inappropriate shocks and ICD-related complications. After noninferiority is established, statistical analysis is done for potential superiority. Secondary endpoint comparisons of shock efficacy and patient mortality are also made. CONCLUSION: The PRAETORIAN trial is a randomized trial that aims to gain scientific evidence for the use of the subcutaneous ICD compared with the transvenous ICD in a population of patients with conventional ICD with respect to major ICD-related adverse events. This trial is registered at ClinicalTrials.gov with trial ID NCT01296022.

Minor elevations in troponin I are associated with mortality and adverse cardiac events in patients with atrial fibrillation.

AIMS: In patients with atrial fibrillation, minor troponin I elevation is regularly detected; however, the prognostic significance of this finding is unknown. We therefore sought to examine the prognostic value of elevated troponin I in patients with atrial fibrillation. METHODS AND RESULTS: A prospective study was conducted analysing all consecutive patients admitted with atrial fibrillation in a 2-year period. Patients with an ST-elevation myocardial infarction (MI) were excluded. Minor troponin elevation was defined as a troponin I level between 0.15 and 0.65 ng/mL, which is still below the 99th percentile of the upper reference limit. A positive troponin I was defined as ≥ 0.65 ng/mL. Study outcomes were all-cause mortality (death), death and myocardial infarction (death/MI), or all major adverse cardiac events (MACE: death, MI, or revascularization). A total of 407 patients were eligible for inclusion. The median duration of follow-up was 688 days. A minor elevation occurred in 81 (20%) patients and 77 (19%) had a positive troponin I. In a multivariate model, minor troponin I elevation and a positive troponin I were independently associated with death [hazard ratio (HR): 2.36, 95% confidence interval (CI): 1.17-4.73 for minor elevation and HR: 3.77, 95% CI: 1.42-10.02 for positive troponin I]. Also, there was an independent correlation between the combined endpoints of death/MI and MACE and both a minor elevation and a positive troponin I. CONCLUSION: Minor elevations in troponin I on hospital admission are associated with mortality and cardiac events in patients with atrial fibrillation and might be useful for risk stratification.

Early markers of atrial fibrillation recurrence after pulmonary vein isolation.

BACKGROUND: Postprocedural atrial extrasystole (AES) frequency predicts atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) in patients with paroxysmal AF. However, the predictive value of preprocedural AES frequency is unknown. We investigate whether preprocedural AES frequency is a feasible marker to predict (timing of) AF recurrence after PVI. METHODS: Patients (N = 684) with paroxysmal or persistent AF undergoing first-time PVI were evaluated for (a) the frequency of AES/day on Holter recordings without AF prior to PVI, (b) AF episodes during the 90 days blanking period, and (c) AF recurrences afterward. The correlation between AES/day and both development and timing of AF recurrences was tested. RESULTS: Preprocedural AES/day was similar in patients with paroxysmal (66 [20-295] AES/day) and persistent AF (115 [12-248] AES/day, P = .915). During the blanking period, 302 (44.2%) patients showed AF episodes. AF recurred in 379 (55.4%) patients at 203 (105-400) days after PVI. AF recurred more frequently in patients with persistent (N = 104 [69.3%]) than in patients with paroxysmal AF (N = 275 [51.5%], P < .001). Frequency of AES prior to PVI was not correlated with development (P = .203) or timing (P = .478) of AF recurrences. AF recurrences occurred both more frequently (P < .001) and earlier (P < .000) in patients with AF during the blanking period. CONCLUSION: AES/day prior to PVI is not correlated with (timing of) AF during the blanking period or AF recurrences, and is therefore not a feasible marker for AF recurrences in patients with PAF. AF during the blanking period is correlated with AF recurrence.

Four-year follow-up of treatment with intramyocardial skeletal myoblasts injection in patients with ischaemic cardiomyopathy.

AIMS: Studies reporting improved left ventricular (LV) function of percutaneous skeletal myoblast (SkM) injection in patients with ischaemic cardiomyopathy had follow-up not exceeding 12 months, and did not include a control group. Our group has reported evidence for myoblast efficacy in the first five out of the 14 treated patients. The objective of the present evaluation was to assess if these effects were sustained at long-term follow-up. We compared function of patients treated with SkM 4 years earlier with a matched control group. Secondary endpoints included mortality, NYHA class, N-terminal pro-B-natriuretic peptide levels, incidence of arrhythmias, and quality of life. METHODS AND RESULTS: Fourteen patients with ischaemic cardiomyopathy who underwent SkM injection were compared with 28 non-randomized control patients matched for age, sex, location, and extent of myocardial infarction. Contrast echocardiography and tissue Doppler imaging (TDI) was performed to compare global and regional LV function. At 4-year follow-up, three patients (21%) had died in the treated group and 11 patients (39%) in the control group (P = 0.8). In the survivors, LV ejection fraction (EF) was 35 +/- 10% and 37 +/- 9% in the SkM group and 36 +/- 8% and 36 +/- 6% in the controls at baseline and 4 years follow-up, respectively (P = 0.96 between groups at follow-up). TDI-derived systolic velocity in the injected sites was 5.4 +/- 1.8 cm/s in the SkM group when compared with 5.1 +/- 1.6 cm/s in corresponding sites in the control group (P = 0.47). None of the secondary endpoints showed a difference between the groups. However, in the patients fitted with an internal cardioverter defibrillator, more arrhythmias leading to interventions occurred in the treated group than in the control group, 87% and 13%, respectively (P = 0.015). CONCLUSION: Percutaneous intramyocardial SkM injection in ischaemic cardiomyopathy has no sustained positive effect on resting global or regional LV function, respectively, at 4-year follow-up. Moreover, the procedure may induce a higher risk of developing serious arrhythmias, but larger patient series are required before more precise characterization of the safety and efficacy profile of the procedure is possible.

Reverse of left ventricular volumetric and structural remodeling in heart failure patients treated with cardiac resynchronization therapy.

Patients with heart failure and mechanical dyssynchrony suffer a progressive increase in left ventricular (LV) mass and asymmetrical regional hypertrophy with eventual poor prognosis. The present study sought to investigate whether cardiac resynchronization therapy (CRT) could reverse these abnormalities. The study included 66 consecutive heart failure patients who received CRT. All patients underwent serial evaluation before, 3 months after, and 12 months after CRT. At 12 months after CRT, 50 patients (76%) were echocardiographic volumetric responders, defined as a >15% reduction in LV end-systolic volume. LV end-systolic volume was decreased from 214 +/- 97 ml to 179 +/- 88 ml at 3 months and was further decreased to 158 +/- 86 ml at 12 months after CRT (all p <0.01). LV ejection fraction was improved from 18% +/- 4% to 28% +/- 7% (p <0.001) at 3 months without further change at 12 months after CRT. LV mass was reduced from 242 +/- 52 g to 222 +/- 45 g at 3 months and was further reduced to 206 +/- 50 g at 12 months after CRT (all p <0.01). Improvement of LV geometry was seen as improvements of the end-diastolic (1.64 +/- 0.14 vs 1.77 +/- 0.17, p <0.001) and the end-systolic (1.63 +/- 0.14 vs 1.99 +/- 0.22, p <0.001) sphericity indexes, respectively, at 3 months, without further significant changes at 12 months after CRT. Volumetric responders had a reduction in LV mass from 240 +/- 50 to 210 +/- 38 at 3 months, and LV mass was further reduced to 186 +/- 37 g at 12 months after CRT (all p <0.01). In contrast, nonresponders had a progressive increase in LV mass from 248 +/- 59 g to 258 +/- 54 g at 3 months, and LV mass was further increased to 269 +/- 60 g at 12 months after CRT (all p <0.05). Likewise, only in volumetric responders, regression of the asymmetric hypertrophy of the lateral wall was noted. In conclusion, CRT results in not only volumetric improvement but also in true reverse LV structural remodeling, evidenced by progressive reduction in LV mass and restoration of regional wall symmetry.

Morphology discrimination in implantable cardioverter-defibrillators: consistency of template match percentage during atrial tachyarrhythmias at different heart rates.

BACKGROUND: Morphology discrimination (MD) in implantable cardioverter-defibrillators (ICDs) is based on the comparison of the ventricular electrogram during tachycardia with a stored reference template obtained during baseline rhythm. However, the effect of heart rate on the template match percentage during supraventricular tachyarrhythmias (SVT) is not known. The purpose of this study was to evaluate the performance of the template match percentage during SVT at different heart rates. METHODS AND RESULTS: Stored electrograms of 868 tachyarrhythmias from 88 patients with a dual-chamber ICD (St Jude Medical, USA) were analysed by the investigators. The effect of heart rate on template match percentage was estimated by regression analysis. For performance measures, data were corrected for multiple episodes in a patient by using the generalized estimating equation method. The mean template match percentage was 86.6 +/- 22.2% (median 100%) for SVT episodes. No significant differences in template match percentage between fast [ventricular cycle length (CL) 300-350 ms] and slow (ventricular CL >400 ms) SVTs were observed (85.4 +/- 27.0 vs. 87.1 +/- 19.7%). Using nominal settings, MD alone provided sensitivity and specificity of 70.2% and 89.4% overall, respectively. Morphology discrimination in conjunction with rate branch analysis, sudden onset, and stability yielded sensitivity and specificity of 98.5% and 91.2%, respectively. CONCLUSION: Morphology discrimination has a consistently high template match percentage during SVTs, which is independent of ventricular CL. The consistent high match percentage results in high specificity for arrhythmia discrimination.

Transcatheter ablation of arrhythmias associated with congenital heart disease.

The improvement of surgical techniques resulted in significant life prolongation of many young patients with congenital heart disease (CHD). However, as these patients reach adulthood, their risk for late complications associated with surgery is also increased. One of the most difficult challenges associated with CHD is the high incidence of cardiac arrhythmias that arise from either the myocardial substrate created by abnormal physiology (pressure/volume changes, septal patches, and suture lines) or the presence of surgical scar. Catheter ablation is proven to be effective in treating atrial and ventricular arrhythmias in structurally normal hearts, and has also been used to treat arrhythmias in adults with congenital heart disease. In this review we provide an overview about diagnostic challenges, mapping and ablation techniques and outcome of patients undergoing transcatheter ablation procedures.

Single-catheter approach for ablation of the slow pathway in a patient with type IV Ehlers-Danlos syndrome and AV nodal reentrant tachycardia using a magnetic navigation system.

Patients with Ehlers-Danlos syndrome type IV have thin-walled, friable arteries and veins. Invasive procedures carry a significantly increased risk for perforation of blood vessels. The aim of this case report is to demonstrate the feasibility and potential benefits of using a stereotactic magnetic navigation system (MNS) for mapping and ablation under these very special circumstances. A 45-year-old woman is presented with daily episodes of typical atrio-ventricular nodal re-entry tachycardias (AVNRT) and known Ehlers-Danlos syndrome type IV. Transcatheter ablation procedure of the AVNRT was undertaken using the MNS, with a non-traumatic single floppy catheter and the capability of advanced navigation.

Baseline predictors of cardiac events after cardiac resynchronization therapy in patients with heart failure secondary to ischemic or nonischemic etiology.

We evaluated the value of baseline parameters derived from tissue Doppler imaging (TDI) for event prediction in patients with heart failure (HF) secondary to ischemic and nonischemic cause who underwent cardiac resynchronization therapy (CRT). Seventy-four consecutive patients with HF (mean age 59 +/- 11 years) underwent CRT. Baseline clinical parameters included New York Heart Association class, 6-minute walking distance, HF cause, and diabetes. TDI-derived parameters included lateral and septal E/E' ratios defined as peak early left ventricular (LV) filling velocity (E wave) to TDI-derived peak early diastolic velocity of the mitral annulus (E' wave). During a median follow-up of 720 days, 21 patients (28%) had cardiac death or hospitalization for HF. These patients more often had an ischemic cause (p <0.05), diabetes (p <0.05), and restrictive filling (p <0.001), less often had LV dyssynchrony (p <0.05), and had higher septal and lateral E/E' ratios (p <0.001 for the 2 comparisons). In a multivariable model using a forward selection algorithm, only the lateral E/E' ratio remained an independent predictor of cardiac outcome. After 3 months of CRT, TDI-derived systolic mitral annular systolic and diastolic velocities improved significantly in nonischemic patients for the septal and lateral sides. In contrast, in ischemic patients no significant improvements were seen. Significant improvements were seen in septal and lateral E/E' ratios in ischemic and nonischemic patients. However, the improvement in lateral E/E' ratio was significantly less and absolute 3-months E/E' ratios were worse in ischemic patients. In conclusion, baseline lateral E/E' ratio is an independent predictor for cardiac events in patients with HF treated with CRT. The worse clinical outcome in ischemic patients may be due to failure of improvement in systolic and diastolic mitral annular velocities after CRT, resulting in a less pronounced improvement in LV filling pressures as demonstrated by this E/E' ratio.

Magnetic navigation in left-sided AV reentrant tachycardias: preliminary results of a retrograde approach.

INTRODUCTION: A novel magnetic navigation system allows remote guidance of floppy radiofrequency (RF) ablation catheters. We evaluated the feasibility of mapping and ablation of left-sided accessory pathways (APs) using the retrograde transaortic approach with this system. This might open the gate to retrograde ablation of left atrial arrhythmias. METHODS AND RESULTS: Twenty consecutive patients were included. A Helios II was used in five and in 15 a Celsius RMT RF catheter with higher magnetic mass and different flexibility was used. Mapping and ablation were attempted. The learning curve was analyzed. Ablation was acutely successful in 60% of the patients using the Helios II and in 80% using the Celsius RMT. Median procedure time was 158 minutes, with median patient and physician fluoroscopy times of 26 and 4 minutes. In the last 10 patients, procedure times became significantly shorter (median 122 minutes, only Celsius RMT catheters) and standard catheters had to be used only twice. No complications occurred. CONCLUSIONS: Remote retrograde transaortic RF ablation of left-sided APs is feasible, safe, and reduces the physician's fluoroscopy exposure. There is a very steep initial learning curve, with the success rate increasing from 50% in the first 10 cases to 80% in the last 10 cases. Different catheter configurations may influence the outcome.

Predictors of cardiac events after cardiac resynchronization therapy with tissue Doppler-derived parameters.

BACKGROUND: To evaluate the prognostic value of tissue Doppler imaging (TDI)-derived parameters (E/E' ratio and Tei index) in heart failure (HF) patients who underwent cardiac resynchronization therapy (CRT). METHODS AND RESULTS: The study comprised 74 consecutive HF patients (mean age 60 +/- 11 years) who underwent CRT. Echocardiography including TDI measurements was performed in all patients at baseline and 3 months after CRT. During a median follow-up period of 720 days (range 210 to 1020 days), 21 patients (28%) had events (8 deaths, and hospitalization for HF in the remaining 13). From the baseline clinical and echocardiography data, univariable Cox-regressions analysis revealed that only diabetes (hazard ratio [HR] 3.703, P < .01), E/A ratio (HR 3.492, P < .001), and E/E' ratio (HR 1.130, P < .001) were predictors for cardiac events. From the 3-month follow-up data, the E/A ratio (HR 2.988, P < .005), E/E' ratio (HR 1.170, P < .001), left ventricular ejection fraction (HR 0.835, P < .01), deceleration time (HR 0.977, P < .05), and the Tei index (HR 15.784, P < .001) were predictors for cardiac events. After multivariable analysis, only diabetes (HR 5.544, P < .05), the 3-month E/E' ratio (HR 1.229, P < .001), and change in Tei index (HR 32.174, P < .001) were independent predictors for cardiac events. Patients with a high baseline and 3-month follow-up E/E' ratio had an 88% cardiac event rate. CONCLUSIONS: The Tei index and E/E' ratio are independent predictors of poor response and cardiac events after CRT.

Reversible left bundle branch block induced congestive heart failure. A case report.

Intraventricular conduction delay in the form of left bundle branch block plays an important role in the genesis and the progression of congestive hart failure. We report on the clinical course of a patient and the improvement in functional status after the disappearance of left bundle branch block, despite withholding cardiac resynchronization therapy.

Implantable defibrillator early after primary percutaneous intervention for ST-elevation myocardial infarction: rationale and design of the Defibrillator After Primary Angioplasty (DAPA) trial.

BACKGROUND: It has been shown that an implantable cardioverter defibrillator (ICD) may be beneficial when added to optimal drug treatment in patients with reduced left ventricular function who survive a myocardial infarction (MI). However, it is not known whether patients with increased risk of death after primary percutaneous coronary intervention (PCI) for ST-elevation MI also have benefit of prophylactic ICD therapy to reduce sudden cardiac death. METHODS AND STUDY DESIGN: The DAPA trial is designed to evaluate the efficacy and safety of ICD in high-risk patients after primary PCI for ST-elevation MI. In this randomized multicenter controlled study, a total of 700 patients will be included. Enrolment started in October 2004. Inclusion criteria are thrombolysis in myocardial infarction flow less than 3 after primary PCI or left ventricular ejection fraction lower than 30% as measured short after admission for the index MI. Patients will be randomized between 30 and 60 days after their MI. The primary end point will be total death during the follow-up period of at least 3 years for each patient. CONCLUSIONS: This multicenter trial of patients at high risk of death after primary angioplasty for ST-elevation MI will evaluate prophylactic ICD therapy in addition to the current standard of care.

Remote magnetic navigation for mapping and ablating right ventricular outflow tract tachycardia.

BACKGROUND: Navigation, mapping, and ablation in the right ventricular outflow tract (RVOT) can be difficult. Catheter navigation using external magnetic fields may allow more accurate mapping and ablation. OBJECTIVES: The purpose of this study was to assess the feasibility of RVOT tachycardia ablation using remote magnetic navigation. METHODS: Mapping and ablation were performed in eight patients with outflow tract ventricular arrhythmias. Tachycardia mapping was undertaken with a 64-polar basket catheter, followed by remote activation and pace-mapping using a magnetically enabled catheter. The area of interest was localized on the basket catheter in seven patients in whom an RVOT arrhythmia was identified. Remote navigation of the magnetic catheter to this area was followed by pace-mapping. Ablation was performed at the site of perfect pace-mapping, with earliest activation if possible. RESULTS: Acute success was achieved in all patients (median four applications). Median procedural time was 144 minutes, with 13.4 minutes of patient fluoroscopy time and 3.8 minutes of physician fluoroscopy time. No complications occurred. One recurrence occurred during follow-up (mean 366 days). CONCLUSION: RVOT tachycardias can be mapped and ablated using remote magnetic navigation, initially guided by a basket catheter. Precise activation and pace-mapping are possible. Remote magnetic navigation permitted low fluoroscopy exposure for the physician. Long-term results are promising.

Evaluation of morphology discrimination for ventricular tachycardia diagnosis in implantable cardioverter-defibrillators.

BACKGROUND: To reduce inappropriate therapy from implantable cardioverter-defibrillators (ICDs), electrogram morphology discrimination has been developed to improve arrhythmia discrimination without compromising device safety. OBJECTIVES: The purpose of this study was to determine the accuracy of the morphology discrimination algorithm for detecting ventricular tachycardia (VT). METHODS: Stored electrograms of 795 tachyarrhythmias from 106 patients with a St. Jude Medical ICD (51 single-chamber and 55 dual-chamber) were analyzed by the investigators. The data were analyzed for morphology discrimination alone, sudden onset and stability, and morphology discrimination in combination with sudden onset and stability. Data were corrected for multiple episodes within a patient with the generalized estimating equation method. RESULTS: Using the nominal template match of 60%, morphology discrimination alone provided sensitivity and specificity of 78% and 95% for single-chamber ICDs and 63% and 92% for dual-chamber ICDs, respectively. Based on the receiver operator characteristic curve, the optimal-match percent threshold was 80% to 85% but at the expense of specificity. Morphology discrimination combined with sudden onset and stability increased sensitivity to 98% with specificity of 86% in single-chamber devices. In dual-chamber devices, the loss in sensitivity is compensated by rate branch analysis, yielding a sensitivity of 98%. CONCLUSION: Arrhythmia discrimination based on electrogram morphology has the potential to reject atrial tachyarrhythmias. However, there is a risk for underdetection of ventricular tachyarrhythmias if arrhythmia discrimination is primarily based on morphology. To guarantee patient safety in single-chamber devices, the morphology discrimination algorithm must be programmed in combination with established detection algorithms. In dual-chamber devices, loss of sensitivity is compensated by the V > A rate branch.

Targets and endpoints in ablation therapy for atrial fibrillation in the light of pathophysiological mechanisms.

Atrial fibrillation (AF), an important public health problem is a complex and multifactorial arrhythmia. Non-pharmacological treatment for symptomatic patients is of increasing importance. The different catheter ablation techniques in AF treatment developed during recent years, all based on different pathophysiological insights, are discussed. The non-standardized use of different follow-up methods after ablation make interpretation and comparison of results difficult.

Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.

OBJECTIVES: The purpose of this randomized study was to investigate the performance of single- and dual-chamber tachyarrhythmia detection algorithms. BACKGROUND: A proposed benefit of dual-chamber implantable cardioverter-defibrillators (ICDs) is improved specificity of tachyarrhythmia detection. METHODS: All ICD candidates received a dual-chamber ICD and were randomized to programmed single- or dual-chamber detection. Of 60 patients (47 male, age 58 +/- 14 years, left ventricular ejection fraction 30%), 29 had single-chamber and 31 had dual-chamber settings. The detection results were corrected for multiple episodes within a patient with the generalized estimating equations method. RESULTS: A total of 653 spontaneous arrhythmia episodes (39 patients) were classified by the investigators; 391 episodes were ventricular tachyarrhythmia (32 patients). All episodes of ventricular tachyarrhythmias were appropriately detected in both settings. In 25 patients, 262 episodes of atrial tachyarrhythmias were recorded. Detection was inappropriate for 109 atrial tachyarrhythmia episodes (42%, 18 patients). Rejection of atrial tachyarrhythmias was not significantly different between both groups (p = 0.55). Episodes of atrial flutter/tachycardia were significantly more misclassified (p = 0.001). Overall, no significant difference in tachyarrhythmia detection (atrial and ventricular) between both settings was demonstrated (p = 0.77). CONCLUSIONS: The applied detection criteria in dual-chamber devices do not offer benefits in the rejection of atrial tachyarrhythmias. Discrimination of atrial tachyarrhythmias with a stable atrioventricular relationship remains a challenge.