PainFree SST Clinical Trial Results Explained: Single-Chamber ICDs

The single-chamber ICD results from the PainFree SST trial were published January 27, 20151, continuing the Medtronic legacy of investigation in shock reduction technology. PainFree SST is the only large shock-reduction trial to report inappropriate shock rates for single-chamber ICD patients. SmartShock™ Technology was tested in a real-world population and was shown to reduce inappropriate shocks in single-chamber and AF patients, for whom discrimination is more challenging. 


Rhythm Discrimination: Real-World Performance in Single Chamber ICD Patients

Listen to Medtronic Scientist James Coles, PhD, explain the real-world performance of rhythm discrimination algorithms in single-chamber ICD patients in the video at right.


The PainFree SST trial enrolled 2,790 patients implanted with single-chamber and dual-chamber ICDs or CRT-Ds with SmartShock Technology in 126 centers worldwide. At one year, 98% of all studied patients were free of inappropriate shock.


1 Auricchio A, Schloss EJ, Kurita T, et al. Low inappropriate shock rates in patients with single and dual/triple chamber ICDs using a novel suite of detection algorithms: PainFree SST Trial Primary Results. Heart Rhythm. 2015; 12(5): 926-936.
Moss AJ, Schuger C, Beck CA, et al. Reduction in inappropriate therapy and mortality through ICD programming. N Engl J Med. December 13, 2012;367(24):2275-2283.
3 Saeed M, Hanna I, Robotis D, et al. Programming implantable cardioverter-defibrillators in patients with primary prevention indication to prolong time to first shock: results from the PROVIDE study. J Cardiovasc Electrophysiol. January 2014;25(1):52-59.

4 Wathen MS, DeGroot PJ, Sweeney MO, et al, for the PainFREE Rx II Investigators. Prospective randomized multicenter trial of empirical antitachycardia pacing versus shocks for spontaneous rapid ventricular tachycardia in patients with implantable cardioverter-defibrillators: Pacing Fast Ventricular Tachycardia Reduces Shock Therapies (PainFREE Rx II) trial results. Circulation. October 26, 2004;110(17):2591-2596.
Sweeney MO, Sherfesee L, DeGroot PJ, Wathen MS, Wilkoff BL. Differences in effects of electrical therapy type for ventricular arrhythmias on mortality in implantable cardioverter-defibrillator patients. Heart Rhythm. March 2010;7(3):353-360.

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Last updated: 
16 Apr 2015