Walk test at increased levels of heart rate in patients with dual-chamber pacemaker and with normal or depressed left ventricular function

Methods and results In nine patients with ejection fraction (EF) <50% (group A) and in seven with EF 50% (group B) haemodynamics were assessed at rest and during three randomized 6-min walk tests at fixed rate of 70, 90, and 110 beats-min(-1). All patients had dual-chamber pacemaker implanted for complete heart block. Left ventricular function was monitored by a radionuclide system. In group A, with increasing pacing-rate from 70 to 110 beats. min', CO did not change both at rest and during walk, whereas end-systolic volume (ESV) increased (P<0.05) and stroke volume (SV) decreased from 68+/-6 to 47+/-9 ml at rest (P<0.0001) and from 112+/-21 to 76+/-17 ml during walk (P<0.005). In group B, with increasing pacing-rate, CO rose from 6.4+/-0.7 to 9.1+/-1.6 l.min(-1) at rest (P<0.001) and from 10+/-1.5 to 14.1+/-2.2 l.min(-1) during walk (P<0.0001), with no change in ESV and SV.

Background This study focuses the role of heart rate on cardiac output (CO) at rest and during walk test in patients with dual-chamber pacemaker and depressed or normal left ventricular (LV) function.