Abstract 1587: Systolic Strain Rate and Long-Term Clinical Events
Peak systolic strain rate (SSR) is correlated to myocardial contractility and has been extensively studied as a more sensitive marker of myocardial function than wall motion analysis and left ventricular ejection fraction (LVEF). Several studies have reported a reduced systolic strain rate in patients with myocardial infarction but data on the prognostic value of measuring strain rate are scarce.
Methods: We prospectively studied 309 patients with MI or unstable angina referred for urgent coronary angiography at a tertiary center. Standard and tissue Doppler echocardiography were performed the day prior to catheterization and data were stored for off-line analysis. Left ventricular walls were imaged individually from the apical views with frame rates > 200Hz. Segments were manually tracked throughout the cardiac cycle and peak longitudinal SSR was assessed in 18 segments by 2 experienced readers blinded to the clinical data. An average of 3 cardiac cycles was measured per segment and global peak SSR was calculated by averaging the 18 segments. LVEF was estimated visually.
Results: A median of 15 segments per patient were analyzable (interquartile range: 12–17 segments). The average global peak SSR was 0.95 ±0.22/s (1 SD). Peak SSR was significantly different between akinetic (0.70 ±0.41/s), hypokinetic (0.82 ± 0.44/s), and normokinetic segments (0.99 ± 0.48/s), p <0.0001. After a median of 2.8 years of follow-up, 21 patients had died [12 cardiovascular (CV) deaths] and 8 patients had experienced a new MI. Global peak SSR correlated with all-cause mortality (HR 0.82 per 0.1/s increase, 95% CI 0.67– 0.99, p =0.04) and combined CV death or MI (HR 0.69, CI 0.57– 0.84, p = 0.0002). However, after adjustment for LVEF neither all-cause death nor CV death or MI were related to global peak SSR (HR 1.03, CI 0.81–1.30, p = 0.82 and HR 0.92, CI 0.72–1.19, p = 0.52, respectively).
Conclusions: Segmental SSR quantifies segmental contractility and global peak SSR is correlated to hard clinical outcomes for patients referred for urgent coronary angiography. The relationship is in part driven by larger reductions in global contractility detectable also by LVEF rather than minor changes in contractility detectable only by SSR analysis.