EUROECHO and other imaging modalities 2012 location:Athens, Greece date:05-08 December 2012
Purpose: Literature gives contradictory information on whether intrinsic myocardial contractility is preserved in heart failure (HF) patients. We recently proposed a novel echocardiographic approach to estimate LV contractility non-invasively by the slope of segmental passive stretch (preS) and systolic strain (SS) relationship. We aimed to apply it in HF patients to address this unresolved question.
Methods: 12 patients with non-ischemic systolic HF (49±14y, NYHA I-III) and 11 controls (CO 53±3y) underwent an echocardiographic examination with narrow sector tissue Doppler imaging (TDI) of the inferoseptal wall (IS). 3 samples manually distributed from base to apex of IS were tracked throughout the cardiac cycle with custom software by setting the reference point at the onset of P wave on ECG. As such, regional preS was measured as peak positive strain after P wave and SS as subsequent systolic shortening. For each subject linear regression between stretch and strain was performed. Mean relations were then determined as an average slope and intercept over all subjects at each stage. LV end diastolic volume (LVEDV) was measured from apical triplane LV acquisition. LV end systolic wall stress was calculated as WS = (p*r) / 2h, (p - systolic blood pressure, r - LV radius, h - LV wall thickness).
Results: HF patients had significantly lower SS (-15.5±4.1% vs -19.7±3.8%), higher LVEDV (107±14 ml vs 166±51 ml) and WS (338±116 mmHg vs 226±31 mmHg), but similar preS (5.2±2.8% vs 5.9±1.7%). Slope of PreS – SS relation was similar in HF and CO groups (p=NS) and intercept was higher in CO (fig).
Conclussion: Similar slopes of regional preS – SS relation in CO and HF patients suggest preserved intrinsic myocardial contractility in HF at rest. Lower intercept values in HF likely result from higher wall stress.