Key result
LVEF ≤40% is linked to a ~65% shallower HRTS after 400-ms pacing versus LVEF >40%.
Why the study?
Heart rate turbulence following ventricular pacing trains may depend on train cycle length, retrograde ventriculoatrial conduction, and left ventricular function, but this relationship was not established.
Does left ventricular dysfunction and train cycle length affect heart rate turbulence after ventricular pacing trains in patients undergoing programmed ventricular stimulation?
Observational (n=82)
Does left ventricular dysfunction and train cycle length affect heart rate turbulence after ventricular pacing trains in patients undergoing programmed ventricular stimulation?
Absolute Event Rate: 6.8% vs 19.6%
p-value: p=0.017
Heart rate turbulence after ventricular pacing trains is attenuated in patients with left ventricular dysfunction, reflecting impaired vagal modulation.
HRT patterns after pacing trains associate with VA conduction and LV dysfunction; leaves open whether HRT during PVS aids risk stratification in observational cohorts.
BACKGROUND: This study tested the hypothesis that heart rate turbulence (HRT) following ventricular pacing trains depends on train cycle length, presence of retrograde ventriculoatrial (VA) conduction, and left ventricular (LV) function. METHODS: We analyzed digital recordings of programmed ventricular stimulation (PVS) performed in 82 patients (57 men) referred for electrophysiologic studies of ventricular arrhythmias, whose mean age was 64 +/- 12 years and LV ejection fraction (EF) was 47 +/- 15%. Profiles of sinus RR intervals after all available 8-beat ventricular pacing trains (600-and 400-ms) were averaged. Heart rate turbulence slope (HRTS) was analyzed as the maximum positive slope of a regression line through a sequence of 2-5 (HRTS2 - HRTS5) consecutive RR intervals within the first 5 RR intervals after the pacing train. RESULTS: Dynamics of RR intervals had biphasic and monophasic patterns, in patients with and without VA conduction, respectively. Sinus nodal response was less prominent after 600-ms than 400-ms pacing trains. After 400-ms pacing trains, HRTS was significantly shallower in patients with LVEF </= 40% than in those with LVEF > 40%. HRTS4 was the best discriminator between the two groups (6.8 +/- 8.6 ms/RR vs 19.6 +/- 26.0 ms/RR, P = 0.017). CONCLUSION: In patients with VA conduction, HRT after ventricular pacing trains reflects a combination of vagal withdrawal due to transient hypotension and suppression of sinus node automaticity. Attenuation of vagal modulation was detected in patients with LV dysfunction during standard PVS.
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Havránek et al. (2007) conducted an observational in ventricular arrhythmias (n=82). Left ventricular dysfunction (LVEF ≤ 40%) vs. LVEF > 40% was evaluated on Heart rate turbulence slope (HRTS4) after 400-ms pacing trains (p=0.017). Heart rate turbulence slope (HRTS4) after 400-ms pacing trains was significantly shallower in patients with LVEF ≤40% compared to those with LVEF >40% (6.8 vs 19.6 ms/RR, P=0.017).
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