Relation between heart rate and left ventricular mechanical dyssynchrony in patients with end-stage renal disease

The effect of heart rate (HR) on left ventricular (LV) mechanical dyssynchrony has not been studied by phase analysis of myocardial perfusion imaging and has yielded conflicting results by echocardiography. We measured indexes of LV dyssynchrony by automated analysis of gated single-photon emission computed tomography in 140 patients with end-stage renal disease (ESRD) and 133 subjects with normal renal function (control group). Patients with abnormal perfusion pattern or QRS duration >120 ms were excluded. HR at time of acquisition of gated images was recorded. LV ejection fraction (EF), volumes, mass, and 2 indexes of dyssynchrony, phase SD and bandwidth, were derived. Almost 50% of patients in each group had an abnormal LVEF (<50%). HR at rest ranged from 48 to 113 beats/min (75 ± 13). Patients with abnormal LVEF had a higher phase SD (30 ± 13° vs 22 ± 11° and 28 ± 16° vs 15 ± 6° for the ESRD and control groups, respectively, p <0.001 each) and higher histographic bandwidth (88 ± 44° vs 62 ± 33° and 80 ± 49° vs 43 ± 14° for the ESRD and control groups, p <0.001 each). Patients with ESRD and normal LVEF had higher SD and bandwidth than the control group (22 ± 11° vs 15 ± 6° and 62 ± 33° vs 43 ± 14°, respectively, p <0.001 each). The control and ESRD groups were divided into tertiles based on HR. The phase SD and bandwidth were similar in the first (slowest HR) and third (highest HR) tertiles in every group (p = NS). There were no significant correlations between phase SD or bandwidth and HR in either group. In conclusion, within the HR range examined in this cross-sectional study, there was no relation between HR at rest and LV dyssynchrony.