Cardiovascular autonomic control in patients undergoing left ventricular assist device (LVAD) support and pharmacologic therapy.

OBJECTIVES

The objective of the study is to determine cardiac autonomic control in patients undergoing assessment for and/or LVAD therapy.

METHODS

Heart rate variability (HRV) was measured in 17 explanted LVAD, 17 implanted LVAD and 23 NYHA III-IV classified chronic heart failure (CHF) patients and ten healthy matched controls under three conditions: supine free breathing, standing and supine controlled breathing. Five measures of HRV were assessed: mean R-R interval (mR-R), high frequency (HF) and low frequency (LF) spectral power, LF in normalised units (LFnu), and LF to HF (LF:HF) ratio.

RESULTS

Repeat measures ANOVA showed significant (p < 0.05) differences in HRV between all three conditions within groups. Lower values were observed in CHF for LF(in log natural units) compared with explanted patients (-1.4 [95% CI -2.6 to -0.7], p = 0.04) and controls (-2.1 [-3.5 to -0.7], p = 0.001) and for LF:HF compared with implanted patients under paced breathing conditions (z = -2.7, p = 0.007) and controls in standing (z = -2.9, p = 0.004) and paced breathing conditions (z = -2.3, p = 0.02). However, no significant differences were seen between explanted, implanted and control groups under any condition.

CONCLUSIONS

Patients implanted with an LVAD and explanted from a LVAD following myocardial recovery demonstrate a more normal dynamic response to autonomic stimuli and have a lower HRV risk profile compared to CHF patients.