麻豆传媒

Young patients face a substantial cumulative exposure to the risks and complications of implantable cardioverter defibrillators (ICD) therapy, a meta-analysis found.

One-fifth of patients with inherited arrhythmia syndromes experienced . Complications from ICD implantation occurred in 22%, while 0.5% had ICD-related mortality.

"The low but not zero risk of ICD-related mortality should be taken into account when considering an ICD," Joris R. de Groot, MD, PhD, of Academic Medical Center in Amsterdam, and colleagues reported in the February issue of Heart Rhythm. "ICD implantation carries a significant risk of inappropriate shocks and inhospital and post-discharge complications in relatively young patients with inherited arrhythmia syndromes."

"There is no doubt that an ICD can be a lifesaving therapy in inherited arrhythmia syndromes. However, in the young population, ICD therapy poses a problem; just as they are exposed for decades to the risk of sudden death, they will also be exposed to the risks of ICD therapy for decades," according to the authors.

"Also, these young patients are more vulnerable to ICD harm because of an active lifestyle and, in pediatric patients, a continuous growth of the thorax. The cumulative risk of complications will therefore be greater in this pool of patients with a longer 'at-risk' period," they added.

Although inherited arrhythmia syndromes "are the major causes of sudden cardiac death in young patients," , of The Hospital for Sick Children in Toronto, wrote in an accompanying editorial, "we should not expose young patients to the increased risk of ICDs unless [it is] clearly outweighed by the benefits."

As such, "since the decision to implant an ICD in patients with inherited arrhythmia syndromes represents a profound life-long decision and commitment, informed consent is mandatory in light of its potential complications," de Groot and colleagues concluded.

They added, however, that in some cases "the potential benefits of ICD implantation can outweigh the risks in selected patients, since complications are almost always manageable, while sudden cardiac death is irretrievable."

Their study pooled data from 4,916 patients who were included in 63 studies.

Annually, event rates were 4.7% for inappropriate shocks, 4.4% for other ICD-related complications, and 0.08% for ICD-related mortality.

While the ICD mortality and complication figures have remained steady over the years, the annual event rate of inappropriate shocks began to drop in 2008 (6.1% before 2008 versus 4.1% after 2008, P=0.002).

Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT), hypertrophic cardiomyopathy (HCM), and short QT syndrome had stronger links to inappropriate shock (P=0.04, P=0.01, P=0.02, respectively).

Additionally, supraventricular tachycardia was the most common reason for inappropriate shocks, making up 13% of all such cases. Lead malfunction, the most likely complication, occurred 10.3% of the time.

"Despite decades of lead innovation, failures of lead design, such as with the Spring Fidelis and Riata lead, remain present and are probably the Achilles' heel of ICD therapy. This might be particularly pertinent in the young, especially those not limited by heart failure, because of their physically active lifestyle," according to the authors.

"The entirely subcutaneous ICD might overcome this predicament, since the absence of transvenous leads might reduce implantation- and lead-related complications in patients without an indication for brady- and antitachycardia pacing," de Groot and colleagues noted.

They added that in the case of inappropriate shocks -- which are "painful, psychologically disturbing, and potentially arrhythmogenic," -- the odds can "be reduced with strategic ICD programming."

Hamilton found that de Groot's study "provides disease-specific data for young individuals," which can be used to better weigh the risks and benefits of long-term ICD therapy for at least two conditions: CPVT and HCM.

"There appear to be limited indications for ICD as primary prevention in CPVT without first maximizing beta-blocker therapy and other therapies such as flecainide [Tambocor]," he wrote. Similarly, "identifying the patient with HCM who will benefit from primary prevention ICD therapy is challenging."