PURPOSE:To examine the ventriculophasic response (VR) in elderly subjects who are pacer-dependent due to complete heart block (CHB).
METHODS:We studied 31 patients with CHB (mean age = 74±13 years, 11 women) who had chronically implanted pacemakers or implanted defibrillators during routine visits to the device clinic. Coronary disease was present in 11 (35%), and 17 (55%) were taking beta-blockers at the time of the study. The pacer function was temporarily programmed to VVI mode at 30 ppm as ECG lead II and intracardiac atrial and ventricular electrograms were recorded at 50 mm/sec paper speed. We defined the VR as being present when the A-A interval surrounding a QRS complex was > 3% less than the A-A interval that immediately preceded a QRS.
RESULTS:For the group, mean left ventricular ejection fraction (LVEF) = 42±17%. A VR was present in 21 (68%) of the subjects. In 7 the A-A encompassing a QRS decreased ≤; 3%; in 3 it increased. In the 21 patients with VR, the average A-A decrease was 7±4%, from mean A-A = 1001±167ms prior to QRS to mean A-A = 925±142 ms flanking a QRS (p < 0.0001). The magnitude of the VR decreased with increasing LVIDD (r = -0.60; p =0.018), with decreasing LVEF (r =0.48; p =0.031) and with increasing QRS duration of the surface ECG (r = -0.45; p =0.034). It did not correlate with intrinsic atrial rate, presence of escape rhythm or the A-V interval of the last A-wave before the QRS. Beta-blocker therapy did not appear to influence these relationships.
CONCLUSION:Approximately two-thirds of elderly, pacer-dependent patients with complete heart block demonstrate ventriculophasic response. Its magnitude correlates with LV function, declining as markers of LV dysfunction deteriorate (larger LV diameter, diminished LVEF, and wider QRS).
CLINICAL IMPLICATIONS:The lack of ventriculophasic response is potentially a marker of deteriorating underlying cardiomyopathy.
DISCLOSURE:Dadu Razvan, None.