Echocardiographic predictors of acute hemodynamic response to right ventricular pacing in hypertrophic obstructive cardiomyopathy
D R Tangkongpanich, D R Mohal, D R Shun-ShinAbstract
Background
Sequential right ventricular pacing (RVP) with an optimal AV delay improves symptoms and increases exercise time in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, the association between echocardiographic parameters and acute hemodynamic response to RVP remains unknown.
Methods
This prospective cohort study was conducted in parallel with the EMORI-HCM trial, an ongoing clinical study involving high precision hemodynamic and echocardiographic assessment of RVP for HOCM. The changes in systolic blood pressure (SBP) and LVOT pressure gradient (LVOT PG) were continuously and simultaneously recorded during the pacing alteration (pacing on and pacing off ) protocol that classified the patients as acute hemodynamic responders and non-responders.
Results
A total of 50 patients underwent the pacing alteration protocol. 27 patients (59%) had SBP improvement and 37 patients (79%) experienced a reduction in LVOT PG when pacing in RV. The mean left ventricular posterior wall thickness (LVPWT) were 15.46 ± 4.03 mm in patients with SBP improvement compared to 12.89 ± 2.47 mm in those with decreased SBP during RVP(P=0.012) and it was significantly associated with acute hemodynamic response during RVP (OR 1.25; 95% confidence interval [CI] 1.03 to1.52; P=0.025). Moreover, the cut-off of the LVPWT at 17.5 mm demonstrated SBP improvement with specificity of 100%(AUC0.703, Youden index 0.385, P 0.021). The average left atrial volume(LAV) was 57.95 ± 39.17 ml in patients with increased SBP and 90.14 ± 67.28 ml in those with stable or decreased SBP (P=0.047). The LA volume of 82.45 ml predicted SBP improvement with the accuracy of 69% (AUC 0.67, P 0.035).
Conclusions
In patients with HCM who have a dual-chamber pacemaker, LVPWT and LAV are associated with SBP improvement during RVP. Furthermore, an LVPWT of 17.5 mm and an LAV of 82.45 mL serve as useful echocardiographic predictors of a favorable hemodynamic response to RVP.Changes in SBP when RVPFor image description, please refer to the figure legend and surrounding text.ROC of LVPWT and LAVFor image description, please refer to the figure legend and surrounding text.