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Diastolic dyssynchrony more frequent than systolic dyssynchrony in HF
Shanks M. J Am Coll Cardiol. 2010;56:1567-1575.
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Patients with HF had a higher frequency of diastolic dyssynchrony vs. systolic dyssynchrony at baseline, study data suggested. Furthermore, baseline intraventricular systolic and diastolic delays were significantly longer in cardiac resynchronization therapy responders vs. nonresponders.
Researchers from the Netherlands analyzed 266 consecutive HF patients (mean age, 65.7 ± 10 years) with color-coded tissue Doppler imaging at baseline, 48 hours and 6 months after cardiac resynchronization therapy (CRT). They defined systolic dyssynchrony as maximal time delay in peak systolic velocities and diastolic dyssynchrony as maximal time delay in peak early diastolic velocities in four basal left ventricular segments, whereas CRT responders were patients with >15% decrease in LV end-systolic volume at 6 months.
According to study results, baseline LV ejection fraction was 25.2 ± 8.1%, with 63.5% of patients categorized as CRT responders. Additional baseline data indicated that systolic and diastolic dyssynchrony incidence at baseline was 46.2% and 51.9%, respectively, whereas the combination of both was 28.6%. For CRT responders vs. nonresponders, researchers reported longer baseline systolic (79.2 ± 43.4 ms vs. 45.4 ± 30.4 ms; P<.001) and diastolic (78.5 ± 52 ms vs. 50.1 ± 38.2 ms; P<.001) delays.
During follow-up, improvements of systolic delays (45.4 ± 31.6 ms at 48 hours; 38.9 ± 26.2 ms at 6 months; P<.001) and diastolic delays (49.4 ± 36.3 ms at 48 hours; 37.7 ± 26 ms at 6 months; P<.001) were reported only in CRT responders.
“High incidence of the baseline intraventricular diastolic dyssynchrony in the responders to CRT and its immediate and sustained improvement with biventricular pacing irrespective of the changes in QRS duration are suggestive of a pathophysiology independent of the electromechanical coupling,” the researchers wrote in the concluding remarks of their study. “More comprehensive evaluation of the electrical and mechanical interactions of the LV myocardium throughout the cardiac cycle may provide further information on the more patient-specific therapeutic strategies in HF patients.”
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