Background: During implantable cardioverter defibrillator insertion, induced ventricular fibrillation followed by test shocks (defibrillation threshold testing [DFT]) is utilized to confirm effective device function. The effect of DFT on ventricular function is uncertain. Brain natriuretic peptide (BNP) is a marker of ventricular dysfunction and hemodynamic stress. We hypothesized that DFT causes increased BNP levels.
Methods: BNP, creatine kinase, creatine kinase-MB (CK-MB), and troponin I (cTnI) were measured in 31 patients (mean age 71.4 years; 12 women) at preinsertion (T1), at 2–4 hours (T2), and at 8–12 hours (T3) after DFT. Biomarker levels were compared in patients receiving one shock (Group A) or two shocks (Group B).
Results: After DFT all biomarkers increased above baseline levels but did not reach levels diagnostic for myocardial infarction. From T1 to T2, elevations in CK-MB and cTnI occurred in the highest proportion of patients (CK-MB 90% and cTnI 84%). From T1 to T3, elevation in BNP and cTnI were most prevalent (BNP 83% and cTnI 90%). Significant increases were measured in BNP levels from T1 to T3 (P = 0.0003), CK-MB levels from T1 to T2 (P < 0.0001), and cTnI levels from T1 to T2 (P < 0.0001) and from T1 to T3 (P < 0.0001). CK-MB levels did not increase significantly from T1 to T3 (P = 0.51).
Conclusions: BNP levels rise progressively after DFT accompanied by early CK-MB increases and sustained increases in cTnI. These data suggest that DFT is associated with hemodynamic stress and left ventricular dysfunction, as evidenced by increases in BNP. (PACE 2011;1–6)