implantable cardioverter-defibrillators

Patients with irregular heartbeats using implantable cardioverter-defibrillators have a good survival rate, but there is frequent recurrence of sustained heart rhythm problems.


Sudden cardiac death (SCD) is a major concern for people who have cardiovascular diseases such as arrhythmogenic right ventricular cardiomyopathy (ARVC). AVRC is a condition that results in interference with either the electroactivity or pumping mechanisms of the heart. The clinical manifestation and progression of ARVC are dependent on several factors, but it increases the risk of SCD. One of the most effective strategies against SCD in patients with a severe clinical status is the use of implantable cardioverter-defibrillators (ICDs).

Chinese researchers followed-up with people living with ARVC and ICDs to analyze the SCD-related outcomes. Thirty-nine patients with ARVC who received ICDs were followed for one year. The clinical diagnosis of ARVC was based on structural, histologic, electrocardiographic (repolarization/depolarization), arrhythmic, and familial features of the disease. The ICDs were capable of detecting arrhythmias (abnormal heart rhythms) and providing suitable pacing against tachycardia (abnormally fast heart rate) and bradycardia (abnormally slow heart rate) rhythms; the ICDs parameters were adjusted when necessary according to the clinical status of each patient.

There was a favorable survival rate. However, an inappropriate ICD intervention determined a shorter survival rate for those patients without broad precordial T-wave inversion (TWI, a measure of the recovery of the ventricles). Malignant ventricular arrhythmia was considered a common event. There was an incidence of about 72% of appropriate ICD firing. The first appropriate ICD firing was observed over two years since implantation in 15% of the patients. Appropriate firings were classified as those which occurred as a result of ventricular tachycardia. Ventricular arrhythmia was the event that triggered the shock therapy in two of the patients. Authors suggested that the risk of ventricular arrhythmia should be used as an indicator for the replacement of an ICD. The cumulative survival rate remained the same regardless of whether the TWI ≥ V1–V3, which is a marker of abnormalities in ventricular repolarization. Some limitations regarding this study are the methodological characteristics such as a retrospective observational study, small sample size, short follow-up, and ICD as a secondary prevention for SCD.

In conclusion, there is a favorable survival rate for patients living with arrhythmogenic right ventricular cardiomyopathy who received implantable cardioverter-defibrillators. However, the recurrence of sustained ventricular tachycardia or ventricular fibrillation is frequent.


Written By: Vagner Raso

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