Abstract 2442: Defibrillation Threshold Testing During Implantable Cardioverter-Defibrillator Implantation is Associated With Temporal Impairment of Cardiac Function
Background: Defibrillation threshold (DFT) testing is routinely performed during implantable cardioverter-defibrillator (ICD) implantation, though it can not always predict clinical success of ICD shock and sometimes causes critical complications, especially in patients with reduced left ventricular (LV) ejection fraction (EF). There, however, are no detailed data regarding the effect of DFT testing on cardiac function. Recently, global strain rate during the isovolumetric relaxation period (SRIVR) by 2-dimensional speckle tracking has been shown to correlate well with LV relaxation. We aimed to assess the effect of DFT testing on the LV myocardium by measuring cardiac biomarkers and by assessing LV systolic and diastolic function using echocardiography.
Methods: We studied 32 patients who underwent ICD implantation and DFT testing: 17 patients with LVEF <40% and 15 patients with LVEF > or = 40%. We measured serum creatine kinase (CK), CK-MB, cardiac troponin T and I, myoglobin, and BNP. We measured LVEF and global SRIVR with EchoPAC PC (GE). All measurements were performed before, immediately after, and 5 min and 4 h after two consecutive 20 joule DFT testing.
Results: There were no significant changes in any of the biomarkers at any measured time point in both groups. LVEF was decreased immediately after and at 5 min after DFT testing and had recovered to the baseline level at 4 h in the reduced-LVEF group, while it showed no significant change in the preserved-LVEF group (reduced-LVEF: 29±11 vs. 26±11* vs. 24±10* vs. 28±11 %, *p<0.05 vs. baseline; preserved-LVEF: 60±9 vs. 59±9 vs. 60±9 vs. 62±4 %, ns). Global SRIVR was decreased immediately after and at 5 min after DFT testing and had recovered to the baseline level at 4 h in both groups (reduced-LVEF: 0.06±0.07 vs. 0.03±0.05† vs. 0.04±0.05† vs. 0.06±0.08 s−1, †p<0.05 vs. baseline; preserved-LVEF: 0.21±0.16 vs. 0.11±0.08‡ vs. 0.11±0.07‡ vs. 0.21±0.17 s−1, ‡p<0.05 vs. baseline).
Conclusions: DFT testing during ICD implantation caused LV systolic dysfunction in the failing heart and also LV diastolic dysfunction irrespective of LVEF, even though serum cardiac biomarkers were unaffected. The necessity of DFT testing should be reconsidered, especially in patients with reduced LVEF.