Aims: Although right ventricular (RV) pacing has a detrimental effect on global left ventricular (LV) function even in some patients with preserved ejection fraction (EF), its mechanism remains unclear.
Methods and results: We studied 116 subjects; 56 patients with RV pacing and preserved EF (all ≥50%), 30 EF-matched controls, and 30 heart failure (HF) patients with RV pacing and reduced EF (all ≤35%). Radial, circumferential, and longitudinal dyssynchrony and function were quantified as standard deviations of the time-to-peak strain and global peak strain from all 16 LV segments using three-dimensional (3D) speckle-tracking strain. The degree of radial and circumferential dyssynchrony and function were similar for patients with RV pacing and preserved EF and controls. However, patients with RV pacing and preserved EF showed a greater longitudinal dyssynchrony of 46 ± 14 vs. 31 ± 9 ms (P < 0.01) and lower global longitudinal strain at 25 ± 4 vs. 34 ± 7% compared with controls (P < 0.001). Furthermore, longitudinal strain at the apical level was significantly lower than that at the mid- and basal level (20 ± 4 vs. 27 ± 5 and 26 ± 5%, P < 0.001), and longitudinal dyssynchrony at the apical level was significantly larger than at the mid- and basal level (44 ± 19 vs. 36 ± 20 and 32 ± 15 ms, P < 0.05) in patients with RV pacing and preserved EF. In contrast, HF patients with RV pacing and reduced EF showed greater radial, circumferential, and longitudinal dyssynchrony, and lower global radial, circumferential, and longitudinal strain than did controls (all P < 0.001).
Conclusion: Three-dimensional speckle-tracking strain was found to be useful for evaluating early subtle changes associated with chronic RV pacing, and may thus play a clinical role in predicting future global LV dysfunction.