Abstract 11232: Utility of Adrenaline Infusion in Evaluation of Patients with Familial Sudden Death and Unexplained Cardiac Arrest
Introduction: Provocative testing is often necessary to unmask the uncommon genetic conditions including primary electrical disease and latent cardiomyopathy that cause cardiac arrest and sudden death. The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) was designed to assess the results of systematic assessment of patients with unexplained cardiac arrest (UCA), their 1st degree relatives, 1st degree relatives of sudden cardiac death (SCD) victims with a negative autopsy, and patients with syncope and documented polymorphic VT.
Methods: After exclusion of structural heart disease and manifest Long QT Syndrome (LQTS, QTc>460 msec male, >480 msec female) patients with UCA and selected family members underwent adrenaline challenge during continuous monitoring at doses of 0.05 mcg/kg/min, 0.10 mcg/kg/min and 0.20 mcg/kg/min. A test was considered positive for LQTS if the absolute QT prolonged by ≥30 msec at 0.10 mcg/kg/min, and borderline if the QT failed to shorten but prolongation was < 30 msec. Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) was diagnosed if adrenaline provoked ≥3 beats of polymorphic VT or bidirectional VT, and borderline for polymorphic couplets or PVCs, or non-sustained monomorphic VT was induced.
Results: One hundred and fifty six patients underwent adrenaline infusion (age 41±16 years, 50% male), including 59% UCA patients, 20% UCA relatives, 15% SCD relatives and 5% patients with syncope and PMVT. One hundred and forty two patients (92%) received the maximum dose. Testing was positive for LQTS in 22 patients (14%), and borderline in 16 (10%). Testing was positive for CPVT in 10 (6%) and borderline in 8 (5%). After all other testing was completed, the working diagnosis was LQTS in 35 patients (22%), CPVT in 15 (10%), idiopathic VF in 52 (33%) and unaffected in 31 (20%). Genetic testing is underway in the majority of patients with diagnostic or borderline responses.
Conclusion: Adrenaline challenge provoked diagnostic abnormalities in 21% of patients, and borderline findings in 15%. The data support a significant role for adrenaline challenge in the workup of suspected familial sudden death syndromes, although precise sensitivity and specificity needs to be established.
- © 2011 by American Heart Association, Inc.