For more precise Atrial Sensing and Less Far-Field R-Wave Interference, the most favorable Electrode Spacing is provided by the device. The P-wave amplitudes drop appreciably at the time of the atrial fibrillation (AF). The device allows 1.1 mm electrode spacing for higher atrial sensitivity settings devoid of improperly sensing extra-atrial signals. As a result more precise medical decision making is possible through more precise diagnostics that is offered by the OptiSense 1999 Pacing Lead with Optim insulation. More precise diagnostics can be offered by the device because of its optimum insulation, finest tip-to-ring spacing, more exact atrial sensing, less far-field interference, slim lead body diameter, lower thresholds that has steroid elution and condensed polarization that has titanium nitride fractal coating. The OptiSense 1999 Pacing Lead has an exclusive 1,1 mm tip-to-ring spacing. At the time of comparison with other atrial leads, with spacing of 10 mm or more, the unique 1,1 mm tip-to-ring spacing feature of OptiSense 1999 Pacing Lead provides more accurate measurement of atrial signals.