Abstract 21347: Acute Recoordination Rather Than Acute Improvement of Systolic Function Determines Long-term Response After Cardiac Resynchronization Therapy
Introduction: Cardiac resynchronization therapy (CRT) improves left ventricular (LV) function acutely, with further improvements and reverse remodelling after long-term pacing.
Hypothesis: Long-term improvement of LV function and reverse remodelling after CRT is determined by acute recoordination rather than by acute improvement of systolic function.
Methods: In 35 heart failure patients, speckle tracking longitudinal strain was assessed at 18 LV segments before, directly after and 6 months after CRT. Systolic discoordination was calculated by the internal strain fraction (ISF=burden of paradoxical stretch relative to normal systolic shortening). Response was assessed by acute and long-term increase in LV ejection fraction (LVEF), decrease in LV volumes, and by acute increase in the invasively determined maximal rate of LV pressure rise (dP/dtmax). Echocardiographic response was defined as ≥15% decrease in LV end-systolic volume.
Results: CRT induced acute and ongoing recoordination in responders (ISF 52.6±17.5 to 24.6±6.8 and 18.6±9.3%, both p<0.01) while nonresponders only showed mild acute recoordination (35.0±13.3 to 30.1±14.6%, p=0.12) without further long-term improvement (28.4±13.3%,p=0.43). Acute improvement of systolic function was present in responders (LVEF 18.2±5.4 to 23.3±7.5%, dP/dtmax 730±229 to 875±174mmHg/s, stroke volume 41±13 to 51±23ml; all p<0.05) and nonresponders (LVEF 19.9±8.3 to 22.6±8.3%, dP/dtmax 644±160 to 738±208mmHg/s; both p<0.05, stroke volume 52±16 to 58±17ml; p=NS). However whereas responders further improved their LVEF (to 31.5±9.3%, p<0.01) by reverse remodelling (LV end-diastolic volume 221±68 to 166±70ml, p<0.01), this effect was absent in nonresponders (LVEF to 21.4±7.9%, LV end-diastolic volume 284±121 to 287±105ml, both p=NS). Acute ISF decrease related to long-term LVEF increase and reverse remodelling (r=0.64 and r=0.66, both p<0.001) while acute LVEF increase only moderately related to long term LVEF increase (r=0.44, p=0.01) and acute dP/dtmax or stroke volume increase neither related to long-term improved LVEF nor to reverse remodelling (all p=NS).
Conclusion: Long-term response to CRT is determined by acute recoordination rather than acute improvement of LV systolic function.
- © 2010 by American Heart Association, Inc.