True bipolar defibrillator leads have increased sensing latency and threshold compared with the integrated bipolar configuration.

Background: Dual-coil implantable defibrillator (ICD) leads with true bipolar pacing and sensing (quadripolar leads) have been introduced to provide improved sensing characteristics without sacrificing defibrillation efficacy. Electrode configuration has been shown to have little effect on the amplitude or slew rate of the intracardiac electrogram, but does have an effect on the duration of the sensed electrogram. Closer spacing of the electrodes and smaller surface area of the anode may, therefore, result in a different latency of sensing relative to the onset of the QRS complex.

Primary prevention of sudden cardiac death: trials in patients with coronary artery disease.

Over the past decade, four randomized, controlled trials have evaluated therapies for prevention of sudden cardiac death in patients with coronary disease. Three of the four trials have shown significant reductions in mortality with implanted defibrillators. Two studies failed to demonstrate any benefit from pharmacologic antiarrhythmic therapy.