The Effects of Shock from Defibrillation Threshold Testing on Cardiac Systolic and Diastolic Function

BackgroundInappropriate implantable cardioverter defibrillator (ICD) shocks are associated with increased overall mortality. However, it remains unclear whether shocks from defibrillation threshold (DFT) testing directly impair cardiac function. MethodsDFT testing was performed in 34 patients who underwent ICD/cardiac resynchronization therapy with a defibrillator implantation/generator exchange. Heart rate and cardiac function, including left ventricular (LV) systolic pressure, LV end-diastolic pressure, peak positive and negative dp/dt ( + dp/dt and -dp/dt, respectively) of LV pressure, and the tau index, were assessed with a Mikro-Cath diagnostic pressure catheter (CD Leycom, Zoetermeer, the Netherlands). These parameters were measured before and 1 minute, 3 minutes, 5 minutes, 10 minutes, and 15 minutes after DFT testing. ResultsPeak positive dp/dt increased over baseline at each interval (976 229 mm Hg/s vs 1,039 +/- 258, 1,049 +/- 245, 1,042 +/- 247, 1,037 +/- 259, and 1,034 +/- 254 mm Hg/s, respectively; P < 0.01). Furthermore, peak negative dp/dt (-1,140 +/- 397 mm Hg/s vs -1,185 +/- 447, 1,193 +/- 435, -1,195 +/- 434, -1,189 +/- 449, and -1,186 +/- 459 mm Hg/s, respectively; P < 0.01) and the tau index (65.1 +/- 18.5 vs 62.5 +/- 16.8*, 62.4 +/- 15.9(**), 63.0 +/- 16.8*, and 62.8 +/- 18.7*, respectively; *P < 0.05, P-** < 0.01) decreased compared to those at baseline at each interval. ConclusionShock after DFT testing improved LV systolic and diastolic function immediately, especially in patients with preserved LV ejection fraction.