Key result
Long-term DDD pacing in drug-refractory HOCM is associated with a ~52% increase in HRV.
Why the study?
Does chronic DDD pacing improve time-domain indexes of heart rate variability in patients with drug-refractory hypertrophic obstructive cardiomyopathy?
Observational (n=21)
Does chronic DDD pacing improve time-domain indexes of heart rate variability in patients with drug-refractory hypertrophic obstructive cardiomyopathy?
p-value: p=<0.001
Chronic DDD pacing in patients with drug-refractory HOCM restores sympathovagal balance by increasing vagal activity, as evidenced by normalized heart rate variability indexes.
DDD pacing was associated with increased HRV in refractory HOCM; hypothesis-generating for autonomic effects, needs RCTs before practice change.
The aim of this study was to examine whether DDD pacing affects time-domain indexes of heart rate variability (HRV) in patients with hypertrophic obstructive cardiomyopathy (HOCM). We studied 11 patients (7 men, age 52 +/- 8 years) with HOCM refractory to drugs. In all patients a DDD pacemaker was implanted and the atrioventricular delay was programmed to ensure a full ventricular activation sequence. Time-domain indexes of HRV (mean NN, SDANN, SDNN, SD, rMSSD, pNN50) were determined from 24-hour Holter recordings 3 days before and 1 year after pacemaker implantation. The pacemaker was turned off during the second recordings. The same indexes were determined in ten healthy controls at the same time points. The controls showed no significant differences in any of the measured parameters between the two time points. The HOCM patients showed an increase in SD (from 27 +/- 13 to 41 +/- 13 ms, P < 0.001), rMSSD (from 18 +/- 5 to 32 +/- 8 ms, P < 0.001), and pNN50 (from 1.03 +/- 1.06 to 8.52 +/- 4.84%, P < 0.0001). As a result, the values of these three parameters, which were lower in the HOCM patients than in the controls before pacing, were restored to normal levels by the end of the study. In conclusion, our findings indicate that long-term pacing in HOCM patients restores the sympathovagal balance in the heart by increasing vagal activity.
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Simantirakis et al. (1999) conducted an observational in Hypertrophic obstructive cardiomyopathy (n=21). DDD pacing vs. Baseline (before pacing) and healthy controls was evaluated on Time-domain indexes of heart rate variability (p=<0.001). Long-term DDD pacing in patients with drug-refractory HOCM significantly increased heart rate variability indexes, including SD (from 27 to 41 ms, P<0.001) and rMSSD (from 18 to 32 ms, P<0.001).
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