Initial clinical experience with a dual chamber rate responsive implantable cardioverter defibrillator

The present study reports the first clinical experience with the Photon DR dual chamber rate responsive ICD. Fifty-seven patients (mean age 67.6 +/- 10 years) with a mean LVEF of 0.332 in NYHA Class I (30%), II (51%), or III (19%) met the implant criteria. Tachyarrhythmia diagnoses included VF (21%), VT (49%), or VT/VF (30%). Additional bradycardia pacing diagnoses included AV block (18%), sinus node dysfunction (5%), and sinus bradycardia (11%). All patients were followed on a long-term basis. A device-based direct current fibrillator (DC fibber) successfully induced VF in 96.2% of 243 attempted inductions. Detection times (2.86 +/- 0.47 s) and redetection times (1.29 +/- 0.32 s) compared favorably with historic controls using a morphology detection (MD) clinical data. Defibrillation energy and voltage thresholds were 10.4 +/- 5.5 J (range 3-28) and 421 V +/- 108 (range 230-696), respectively. Ninety-two clinical arrhythmias were recorded. Using a nominal nonindividualized algorithm, the sensitivity for VT detection was 100% and specificity for SVT rejection 81%. There were six patient deaths (2 nonsudden arrhythmic, 2 cardiac, 2 other). In conclusion, early clinical experience with the Photon DR ICD supports its safety, efficacy, and ability to provide advanced dual chamber ICD features.