Incidence and clinical predictors of low defibrillation safety margin at time of implantable defibrillator implantation

Abstract

The incidence of low DSM patients is low with high-energy devices. Amiodarone use is associated with low DSM, and its discontinuation or substitution with sotalol is one of a variety of available options for low DSM patients.

Reassessing Risk Factors for High Defibrillation Threshold: The EF‐SAGA Risk Score and Implications for Device Testing

“…This may be due to the variable patient responses to amiodarone's sodium, calcium, and potassium channel inhibition, as has been previously suggested. 9 While African-American ethnicity was not found to be an independent risk factor for high DFT, our African-American ICD recipients were younger and had more severe LV dysfunction compared to all other ethnicities combined, consistent with findings reported by Thomas et al 17 Interestingly, in the United States, the incidence of heart failure before 50 years of age is significantly more common among blacks than whites. 18 Compared to other ethnicities, African Americans have the highest incidence of hypertension with associated dilated cardiomyopathy, end-stage renal disease, stroke, and death.…”

“…The reason for this relationship is unclear. Both Cheng et al 9 and Gold et al 12 previously noted that high DFT patients were on average younger than patients with adequate DFT, but this finding was not significant in their studies. Interestingly, two previously demonstrated independent predictors of high DFT-increased LV dimensions and increased LV mass-happen to peak in the general population in the third and fourth decades of life, respectively, which may influence their DFT thresholds.…”

“…Last, the use of amiodarone was an independent predictor of high DFT in our study. While studies on the impact of amiodarone use on DFT thresholds have had conflicting results, Cheng et al 9 as well as Lubinski et al 16 have similarly reported it as an independent predictor of high DFT. This may be due to the variable patient responses to amiodarone's sodium, calcium, and potassium channel inhibition, as has been previously suggested.…”

“…Patients in the high DFT group received a mean of 12.3 ± 7.5 ICD test shocks (range 2-30) compared to 2.0 ± 1.4 shocks (range [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] in the satisfactory DFT group (P < 0.0001). The average patient age was 60.2 years, of which the high DFT group was significantly younger (55.6 years vs 60.3 years, P = 0.04) than the satisfactory DFT group.…”

“…[5][6][7][8] Amiodarone use may also be associated with a low defibrillation safety margin. 9 Because of these concerns, some operators still perform device testing at the time of implantation to ensure an adequate safety margin between the successful defibrillation energy and the maximum device output. Historically, a safety margin of at least 10 Joules has been considered to be acceptable.…”