Follow-Up Defibrillator Testing for Antiarrhythmic Drugs

Wood, Mark A.; Ellenbogen, Kenneth A.

doi:10.1161/circulationaha.106.637397

Cited by 8 publications

(3 citation statements)

References 17 publications

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“…If the DFT is known to be low (≤15 J), the risk of an increase sufficient to prevent defibrillation with maximum output is sufficiently low that repeat defibrillation testing is not required 115 . However, if the defibrillation safety margin at implant is small or unknown, follow‐up defibrillation testing is usually recommended after the loading phase of amiodarone therapy 163 . Patients taking amiodarone are three times more likely to have high DFTs than patients not taking amiodarone 61 …”

Section: Factors That Influence Required Defibrillation Shock Strengtmentioning

confidence: 99%

“…115 However, if the defibrillation safety margin at implant is small or unknown, follow-up defibrillation testing is usually recommended after the loading phase of amiodarone therapy. 163 Patients taking amiodarone are three times more likely to have high DFTs than patients not taking amiodarone. 61 In general, sodium channel blocking drugs increase DFTs.…”

Section: Antiarrhythmic Drugsmentioning

confidence: 99%

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The Dilemma of ICD Implant Testing

Swerdlow

Russo

DeGroot

2007

Pacing Clinical Electrophis

130

112

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Ventricular fibrillation (VF) has been induced at implantable cardioverter defibrillator (ICD) implant to ensure reliable sensing, detection, and defibrillation. Despite its risks, the value was self-evident for early ICDs: failure of defibrillation was common, recipients had a high risk of ventricular tachycardia (VT) or VF, and the only therapy for rapid VT or VF was a shock. Today, failure of defibrillation is rare, the risk of VT/VF is lower in some recipients, antitachycardia pacing is applied for fast VT, and vulnerability testing permits assessment of defibrillation efficacy without inducing VF in most patients. This review reappraises ICD implant testing. At implant, defibrillation success is influenced by both predictable and unpredictable factors, including those related to the patient, ICD system, drugs, and complications. For left pectoral implants of high-output ICDs, the probability of passing a 10 J safety margin is approximately 95%, the probability that a maximum output shock will defibrillate is approximately 99%, and the incidence of system revision based on testing is < or = 5%. Bayes' Theorem predicts that implant testing identifies < or = 50% of patients at high risk for unsuccessful defibrillation. Most patients who fail implant criteria have false negative tests and may undergo unnecessary revision of their ICD systems. The first-shock success rate for spontaneous VT/VF ranges from 83% to 93%, lower than that for induced VF. Thus, shocks for spontaneous VT/VF fail for reasons that are not evaluated at implant. Whether system revision based on implant testing improves this success rate is unknown. The risks of implant testing include those related to VF and those related to shocks alone. The former may be due to circulatory arrest alone or the combination of circulatory arrest and shocks. Vulnerability testing reduces risks related to VF, but not those related to shocks. Mortality from implant testing probably is 0.1-0.2%. Overall, VF should be induced to assess sensing in approximately 5% of ICD recipients. Defibrillation or vulnerability testing is indicated in 20-40% of recipients who can be identified as having a higher-than-usual probability of an inadequate defibrillation safety margin based on patient-specific factors. However, implant testing is too risky in approximately 5% of recipients and may not be worth the risks in 10-30%. In 25-50% of ICD recipients, testing cannot be identified as either critical or contraindicated.

show abstract

Section: Factors That Influence Required Defibrillation Shock Strengtmentioning

confidence: 99%

Section: Antiarrhythmic Drugsmentioning

confidence: 99%

The Dilemma of ICD Implant Testing

Swerdlow

Russo

DeGroot

2007

Pacing Clinical Electrophis

130

112

View full text Add to dashboard Cite

show abstract

“…Careful testing of DFTs should be performed in all the patients, with special attention to those who have monophasic waveform ICDs, those with an epicardial lead system 39 , patients with a high DFT at baseline, and patients treated with high dose, 40 chronic amiodarone. [41][42][43][44] Azimilide has been shown to have minimal effects on the DFT or pacing thresholds in ICD patients. 24,45 Similarly, dronedarone has been shown to have no effect on defibrillation safety margin or pacing thresholds at its therapeutic dose or higher.…”

Section: Drug-device Interactionmentioning

confidence: 99%