[Permanent variable frequency cardiac pacing: which patients with chronic complete atrioventricular block profit...

The authors examined 27 patients with chronic complete atrioventricular block (AVIII) and an implanted pacemaker with rate responsive pacing (RRP), controlled by atrial frequency (DDD stimulation--19 patients) or the length of the QT interval (VVIR pacing--8 patients). The loading test in AVIII ventricular stimulation 70/min (VVI 70) and RRP proved a more than double asset of MKP in RRP, as compared with VVI 70 (55.5 +/- 43.3% vs. 24.3 +/- 34.1%, p less than 0.001). The difference was greater in acquired than in congenital AVIII (27.7 +/- 18.5% vs. 8.4 +/- 4.1%, p less than 0.002) and in patients where the maximum heart rate on VVI did not exceed 70/min, as compared with the remainder (29.3 +/- 19.1% vs. 12.7 +/- 8.1%, p less than 0.002). The difference of MPK in RRP and VVI 70 was inversely correlated with MPK on VVI 70 (r = -0.412, p less than 0.03). MPK on AVIII and MTF on VVI 70 (r = -0.386, p less than 0.05). RRP in patients with AVIII thus causes a double increase of MPK, as compared with VVI pacing. A greater asset can be expected in patients with acquired AVIII, with a lower working capacity and heart rate recorded during the loading test before implantation.