Transvenous implantable cardioverter defibrillators (ICD) were yesterday. The latest craze is innovative extravascular ICD systems. You can find out here whether they will become the new standard and how practical they are.
Implantable cardioverter defibrillators (ICD) are for protection once morest sudden cardiac death established in patients with primary or secondary prophylactic indication. ICDs can save lives.
Farewell to transvenous electrodes
However, problems can arise with transvenous ICD systems, in which the electrode is advanced into the heart via a vein. These include infections or mechanical complications such as a perforation. The subcutaneous ICD is used to minimize such undesirable, sometimes life-threatening events developed been. It works entirely without transvenous electrodes.
Disadvantages of this method, however, are that anti-bradycardia stimulation is very limited and anti-tachycardia pacing (ATP) is not possible at all. With the development of the Extravascular Implantable Cardioverter Defibrillator (EV-ICD) was triedto manage without transvenous electrodes and still have the possibility of anti-bradycardia stimulation and ATP.
EV-ICD: Safer and more effective
With the EV-ICD, the electrode is not implanted transvenously but extravascularly under the breastbone close to the heart. The ICD unit is implanted laterally in the midaxillary area. At the ESC Congress 2022 in Barcelona, the results of the first larger ones, carried out at 46 centers in 17 countries, were presented Study (Extravascular ICD Pivotal Study) on the efficacy and safety of the EV-ICD system in patients with an indication for primary or secondary preventive ICD implantation. The study was New England Journal of Medicine published.
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356 patients with a class I or IIa indication for an ICD were included in the study. An implantation was then performed in 316 patients. In 302 patients during ventricular implantation cardiac arrhythmias were triggered and the complete test protocol of the Defibrillation performed, defibrillation was successful 98.7 percent of the time (p<0.001 for comparing the lower bound of the confidence interval with the defined performance target of 88 percent). There were no serious intraprocedural complications. Of the 316 patients, 299 (94.6 percent) were discharged with a functioning ICD system.
At six months, in this group, 92.6 percent (p<0.001 for comparing the lower limit of confidence interval with the defined performance target of 79 percent) free of serious system- or procedure-related complications. With these results, the goals set might be achieved for both the effectiveness and safety endpoints of the study.
From inadequate shocks and other complications
In a mean follow-up of 10.6 months, a total of eight EV-ICD systems had to be explanted, four of them (1.3 percent) due to infections that had occurred. cases of Mediastinitis, Sepsis or Endocarditis, which were possibly related to the extravascular ICD, might not be documented. After 6 months, a total of 25 complications were recorded in 23 of 316 study participants (7.3 percent). Electrode dislocations were the most common (ten events in nine patients).
A total of 118 inappropriate shocks were detected in 29 patients associated with 81 recorded arrhythmia events. In most cases, this was due to a T waves-Oversensing (in 34 out of 81 episodes; 42 percent). The 8.5 percent inappropriate shock rate at six months, while higher than that of current transvenous ICD systems, is comparable to the rates of early-generation transvenous and subcutaneous systems. The authors of the study report that new algorithms have been developed to prevent inappropriate shocks from the EV-ICD. A clinical test is still pending.
A limitation of the study is the single-arm design due to the lack of a comparison group with implanted transvenous or subcutaneous ICD systems. With regard to the generalizability of the results, the authors concede that given the relatively young age of the study participants (mean 53 years), it is unclear whether the results can also be transferred to older and sicker patients with an ICD indication.
summary
The first prospective multicenter study showed that the new, innovative extravascular ICD system, in which the electrode is implanted under the breastbone, ventricular tachycardia successfully discovered and terminated. However, the rate of inappropriate shock delivery at 6 months was higher than with currently used transvenous ICDs. Further studies are needed to further validate the safety and effectiveness of the extravascular ICD.
Image source: Maros Misove, Unsplash