R Wave Sensing After VT Ablation
R Wave Sensing After VT Ablation
Sustained, monomorphic ventricular tachycardia (VT) is most commonly encountered in patients
 with structural heart disease, usually with ischemic aetiology. It has been proven that
 repeated episodes of sustained VT contribute to the mortality of patients with structural
 heart disease. These patients are usually implanted with implantable cardioverter
 defibrillator without (ICD) or with cardiac resynchronisation therapy (CRT-D). According to
 the current guidelines 3D mapping with radiofrequency (RF) ablation of the tachycardia
 substrate is an established therapeutic option. As part of the clinical follow-up of patients
 implanted with cardiac implantable electronic devices (CIED), CIED function parameters are
 monitored every 6 months, which is always done before and after any procedure involving RF
 ablation. Furthermore, a transient drop of R wave sensing has been demonstrated after the
 atrioventricular (AV) node ablation in patients with single-chamber pacemakers and fast
 atrial fibrillation. The aim of this study is to assess the change in R wave sensing after
 the RF ablation of VT substrate.

 This study will be performed as a clinical, prospective, multi-centre, observational cohort
 study with a structured follow-up period of 12 months. All consecutive patients with
 sustained VT implanted with ICD or CRT-D undergoing RF ablation procedure of myocardial
 substrate, who are able to understand and sign informed consent, will be enrolled. Primary
 objective is a R wave sensing drop > 30% after VT substrate ablation procedure. Recruiting
 should not exceed 12 months with the minimal follow-up period of 12 months (24 months in
 total). Standardized statistical methods and test will be done using SPSS Software Version
 22.0 or newer.

 This unique study offers the possibility to show the impact of RF ablation on short-term and
 long-term R wave sensing change assessed by ICD or CRT-D's ventricle electrode in patients
 with sustained VT and structural heart disease undergoing ablation procedure. This
 observational data is needed to further refine the treatment of these patients and to prevent
 possible ICD/CRT-D dysfunction which could endanger this patient population.
Sustained, monomorphic ventricular tachycardia (VT) is most commonly encountered in patients
 with structural heart disease, usually with ischemic aetiology. It has been proven that
 repeated episodes of sustained VT contribute to the mortality of patients with structural
 heart disease. These patients are usually implanted with implantable cardioverter
 defibrillator without (ICD) or with cardiac resynchronisation therapy (CRT-D) as part of
 sudden cardiac death (SCD) prevention and have had activation of the device due to the
 sustained VT episodes. According to the current guidelines 3D mapping with radiofrequency
 (RF) ablation of the tachycardia substrate is an established therapeutic option. As part of
 the clinical follow-up of patients implanted with cardiac implantable electronic devices
 (CIED), including ICDs and CRT-Ds, function parameters are monitored every 6 months. The same
 check-up is done before and after any procedure involving RF ablation. Furthermore, a
 transient drop of R wave sensing has been demonstrated after the RF ablation of the
 atrioventricular (AV) node in patients with uncontrollable fast atrial fibrillation implanted
 with single-chamber pacemakers. The above mentioned have not been studied yet in patients
 ablated due to sustained VT. Hence, the aim of this study is to assess the change in R wave
 sensing after the RF ablation of VT substrate in patients with structural heart disease.

 This study will be performed as a clinical, prospective, multi-centre, observational
 (analytic, longitudinal) cohort study with patient enrolment in 4 electrophysiology centres
 in Croatia and Switzerland and a structured follow-up period of 12 months.

 All consecutive patients with sustained VT implanted with ICD or CRT-D undergoing RF ablation
 procedure of myocardial substrate, who are able to understand and sign informed consent, will
 be enrolled.

 Exclusion criteria:

 -  Patients with combined mechanical aortic and mitral valve prostheses

 -  Patients with RF ablation of VT done in the last 12 months

 -  Patients with known damaged ICD/CRT-D electrode or battery

 -  Patients undergoing VT ablation who have not been implanted with ICD or CRT-D

 -  Patients not willing or able to undergo clinical follow-up of ICD/CRT-D device

 -  Patients with life expectancy < 1 year

 -  Not able to understand or willing to sign informed consent

 -  Age < 18 years Primary objective is a R wave sensing drop > 30% after VT substrate
 ablation procedure.

 Specific (secondary) end-points:

 -  incidence of VT recurrence after the ablation procedure;

 -  risk factors for R wave sensing drop (> 30%) after the RF ablation of VT substrate;

 -  time needed for R wave sensing recovery after the RF ablation procedure. Recruiting
 should not exceed 12 months with the minimal follow-up period of 12 months (24 months in
 total).

 The risk categorisation of the study was done and the study was awarded a risk category A.

 Sample size was chosen according to annual procedure volumes in Croatia and Switzerland. In
 addition, it is confirmed by power test (number needed to recruit: 52). Recruiting should not
 exceed 12 months. Categorical variables will be presented by contingency tables in absolute
 values and percentages. Categorical variables will be compared by the chi-square with Yates
 corrections or Fisher's exact test. Continuous data will be expressed as means and standard
 deviations or median with corresponding interquartile range. The differences in quantitative
 variables will be tested by Mann-Whitney U-test (non-parametric test for independent
 samples). Logistic regression will be used to analyse the association between all variables
 of interest and the R wave sensing drop. Multivariate logistic regression will be used to
 adjust for confounding factors. Predictors of the R wave sensing drop will be assessed in a
 univariate and multivariate Cox proportional hazards model. The statistical analysis will be
 done using SPSS Software Version 22.0 or newer (IBM SPSS Statistics, New York, USA).

 This unique study offers the possibility to show the impact of RF ablation on short-term and
 long-term R wave sensing change assessed by ICD or CRT-D's ventricle electrode in patients
 with sustained VT and structural heart disease undergoing ablation procedure. This
 observational data is needed to further refine the treatment of these patients and to prevent
 possible ICD/CRT-D dysfunction which could endanger this patient population. Despite a high
 number of cohort registries for cardiovascular diseases (e.g. Danish heart registry,
 ORBIT-AF, GARFIELD AF registry, Swiss AF registry), there are scarce data on patients with
 structural VT and no data regarding R wave sensing changes influenced by RF energy
 application in ventricles. In addition, this could influence obligatory rhythm-monitoring
 duration and consequently hospitalization duration of patients with VT undergoing RF ablation
 procedures. Apart from the above mentioned, in those patients with non-optimal preprocedural
 R wave sensing, this could mean contraindication for procedure or having the need to do
 postprocedural defibrillation testing. It is likely, that data from our study will lead to
 future changes in periprocedural planning and modalities.

 This study will be conducted in compliance with the current version of the Declaration of
 Helsinki, the ICH-GCP or ISO EN 14155 (as far as applicable) as well as all national legal
 and regulatory requirements. According to ethical regulations, the study plan with the
 proposed participant information and consent form as well as other project-specific documents
 will be submitted to Ethic committee of the participating centres.
Inclusion Criteria:

 -  patients with recurrent, sustained ventricular tachycardia

 -  patients implanted with implantable cardioverter defibrillator (ICD) or cardiac
 resynchronization therapy cardioverter defibrillator (CRT-D)

 -  patients planned for 3D mapping and radiofrequency ablation of ventricular tachycardia
 myocardial substrate

 -  patients who are able to understand and sign informed consent

 Exclusion Criteria:

 -  Patients with combined mechanical aortic and mitral valve prostheses

 -  Patients with RF ablation of VT done in the last 12 months

 -  Patients with known damaged ICD/CRT-D electrode or battery

 -  Patients undergoing VT ablation who have not been implanted with ICD or CRT-D

 -  Patients not willing or able to undergo clinical follow-up of ICD/CRT-D device

 -  Patients with life expectancy < 1 year

 -  Not able to understand or willing to sign informed consent

 -  Age < 18 years