Delayed Defibrillation Testing in Patients CRT-D
Delayed Defibrillation Testing in Patients CRT-D
Background: Defibrillation testing (DT) at the end of the implantation of cardiac resynchronization pacemaker with a defibrillator (CRT-D) exposes heart failure (HF) patients to increased procedural risks. However, until now, delayed DT has not been assessed as a possible option in HF patients implanted with CRT-D.
Objective: Aim of the present study is to assess safety and feasibility of delayed DT in HF patients treated with CRT-D.
Material and Methods: Two hundred and eleven consecutive patients (mean age: 65 years, mean NYHA class 3.0, mean EF: 29.3%) underwent CRT-D implantation from October 1999 to December 2004. In the first 17 patients, DT was performed at the end of CRT-D implantation. In the other 194 consecutive patients, DT was performed at 2 months after CRT-D implantation. Outcome of DT, as well as "acute" LV lead dislodgment rate were evaluated in the latter group of 194 patients undergoing a delayed DT. Also, ICD function was assessed through device telemetry analysis at 2 months.
Results: At delayed DT, first shock was effective in 187 of 194 patients (96%), ineffective VF interruption at maximum energy occurred only in one patient (0.5%), and acute LV lead dislodgment was 1%. No ICD therapy failure occurred in the 2-month untested period.
Conclusion: DT performed 2 months after CRT-D implantation is safe and feasible; this is possibly related to the improvement of clinical conditions and hemodynamic status as well as greater lead stability 2 months after CRT-D.
Cardiac resynchronization therapy (CRT) is indicated for the management of patients with drug-refractory heart failure (HF), New York Heart Association (NYHA) class IIIIV, low ejection fraction, and evidence of left ventricular (LV) conduction delay. The addition of the defibrillator function (CRT-D) produces further mortality reduction in this population.
Routine defibrillation testing (DT) is usually performed at the end of conventional ICD implantation (intraoperative testing) to confirm appropriate device function (ventricular fibrillation detection and interruption). With recent advances in ICD technology, device-related problems are becoming less common due to utilization of endocardial rather than epicardial systems, pectoral approach instead of abdominal implants, and active can devices with bipolar shock waveforms. As a consequence, considerable reduction in defibrillation thresholds have been achieved and important increases in defibrillation threshold above safety margins are much less likely to occur over time.
These technical innovations, coupled with expanding evidence supporting ICD implant for primary prevention of sudden cardiac death, have questioned the utility of DT mainly based on concerns for patient safety and for cost considerations.
DT in patients implanted with CRT-D devices deserves special consideration. Candidates to CRT-D are HF patients on optimized drug therapy who have severely reduced left ventricular function and are at high risk for sudden cardiac death. This has two implications for DT. First and foremost, DT is warranted in this high-risk patient population. Second, compromised left ventricular function exposes to greater anesthesiological and cardiovascular risks especially during lengthy procedures.
In addition, DT performed during implantation could theoretically expose the patient to an increased risk of acute left ventricular lead dislodgment (passive catheters).
Therefore, the present study proposes, for the first time, that "delayed" DT may be the best approach to test CRT-D devices. Delayed DT has thus far never been investigated and, therefore, the aim of this observational study is to assess both feasibility and safety of "delayed" DT in heart failure patients implanted with CRT-D devices.
Background: Defibrillation testing (DT) at the end of the implantation of cardiac resynchronization pacemaker with a defibrillator (CRT-D) exposes heart failure (HF) patients to increased procedural risks. However, until now, delayed DT has not been assessed as a possible option in HF patients implanted with CRT-D.
Objective: Aim of the present study is to assess safety and feasibility of delayed DT in HF patients treated with CRT-D.
Material and Methods: Two hundred and eleven consecutive patients (mean age: 65 years, mean NYHA class 3.0, mean EF: 29.3%) underwent CRT-D implantation from October 1999 to December 2004. In the first 17 patients, DT was performed at the end of CRT-D implantation. In the other 194 consecutive patients, DT was performed at 2 months after CRT-D implantation. Outcome of DT, as well as "acute" LV lead dislodgment rate were evaluated in the latter group of 194 patients undergoing a delayed DT. Also, ICD function was assessed through device telemetry analysis at 2 months.
Results: At delayed DT, first shock was effective in 187 of 194 patients (96%), ineffective VF interruption at maximum energy occurred only in one patient (0.5%), and acute LV lead dislodgment was 1%. No ICD therapy failure occurred in the 2-month untested period.
Conclusion: DT performed 2 months after CRT-D implantation is safe and feasible; this is possibly related to the improvement of clinical conditions and hemodynamic status as well as greater lead stability 2 months after CRT-D.
Cardiac resynchronization therapy (CRT) is indicated for the management of patients with drug-refractory heart failure (HF), New York Heart Association (NYHA) class IIIIV, low ejection fraction, and evidence of left ventricular (LV) conduction delay. The addition of the defibrillator function (CRT-D) produces further mortality reduction in this population.
Routine defibrillation testing (DT) is usually performed at the end of conventional ICD implantation (intraoperative testing) to confirm appropriate device function (ventricular fibrillation detection and interruption). With recent advances in ICD technology, device-related problems are becoming less common due to utilization of endocardial rather than epicardial systems, pectoral approach instead of abdominal implants, and active can devices with bipolar shock waveforms. As a consequence, considerable reduction in defibrillation thresholds have been achieved and important increases in defibrillation threshold above safety margins are much less likely to occur over time.
These technical innovations, coupled with expanding evidence supporting ICD implant for primary prevention of sudden cardiac death, have questioned the utility of DT mainly based on concerns for patient safety and for cost considerations.
DT in patients implanted with CRT-D devices deserves special consideration. Candidates to CRT-D are HF patients on optimized drug therapy who have severely reduced left ventricular function and are at high risk for sudden cardiac death. This has two implications for DT. First and foremost, DT is warranted in this high-risk patient population. Second, compromised left ventricular function exposes to greater anesthesiological and cardiovascular risks especially during lengthy procedures.
In addition, DT performed during implantation could theoretically expose the patient to an increased risk of acute left ventricular lead dislodgment (passive catheters).
Therefore, the present study proposes, for the first time, that "delayed" DT may be the best approach to test CRT-D devices. Delayed DT has thus far never been investigated and, therefore, the aim of this observational study is to assess both feasibility and safety of "delayed" DT in heart failure patients implanted with CRT-D devices.
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