1. Kayyali, Andrea MSN, RN

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According to this study:


* The rate of malfunction and the clinical effects of failure are the primary considerations in the replacement of a recalled implantable pacemaker or cardioverter-defibrillator.



After an advisory warning has been issued, the decision to replace a possibly defective implanted cardiac device can be a complicated one: the risk of replacement can outweigh the risk of potential malfunction. To help clinicians make such a decision, researchers devised a model for the evaluation of the risks and benefits associated with two possible treatment options-immediate replacement and continued monitoring. They found that the significant variables for clinicians to consider are the rate of failure of the device, the consequences if failure occurs, and to a lesser extent, the mortality rate associated with replacement.


The decision model was constructed with the life expectancy associated with each strategy as the primary end points; the key variables considered were the initial reason for insertion of the device (the prevention of sudden cardiac death, therapy for ventricular tachycardia or atrioventricular block, for example), the probable clinical outcome in the event of a malfunction, the rate of failure cited in an advisory warning, and the mortality rate associated with its replacement. The researchers conducted probability and sensitivity analyses oriented toward three primary clinical outcomes-failure of the device producing great risk of immediate death, the risk of later death related to an event such as ventricular tachycardia, or symptoms with little risk of death.


They found that when the patient is entirely dependent on a pacemaker and its rate of failure is cited as more than 0.3%, replacement is warranted. In patients with cardioverter-defibrillators implanted primarily to correct a ventricular tachyarrhythmia, a 3% failure rate was found to be the threshold warranting replacement of the device, but that rate could be lowered to almost 1% as procedure mortality rates decrease to 0.1% or the risk of fatal arrhythmias increases to 20% per year. Generally, patients considered to be at low risk for death resulting from an underlying cardiac condition were determined to benefit most from ongoing monitoring, not replacement, of a cardiac device.


The researchers conclude that the risks of replacing a device outweigh the benefits in most cases, unless the rate of failure associated with it is very great.


Amin MS, et al. JAMA 2006;296(4):412-20.