Force-based left ventricular contractile reserve predicts outcome in patients with exercise stress echocardiography without regional wall motion abnormalities

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Investigaciones Médicas, Cardiodiagnostic Introduction. The behavior of the ejection fraction (EF) during exercise stress echocardiography (ESE) is used to measure the left ventricular (LV) contractile reserve (CR). Ventricular Elastance or Force defined as the ratio between systolic blood pressure (SBP) and LV end-systolic volume (ESV) could be better as it is less dependent of heart rate, preload, and afterload conditions. Objective. To establish the relative prognostic value of EF-based and novel Force-based LVCR in patients (pts) without ischemia during ESE. Materials and methods. In a retrospective analysis of prospectively enrolled pts, we enrolled  904 pts, (61.92 ± 12.59 years, 509 men, 56.3%) with negative ESE for RWMA. LV volumes were measured with biplane Simpson’s rule. LVCR was assessed based on EF ≥5 points increase at peak over rest and based on Force peak/rest ratio > 2. The average follow-up was 17.7 ± 5.44 months. Major cardiovascular event was defined as: death, acute myocardial infarction, cerebrovascular accident and/or need for hospitalization due to cardiovascular causes. Results. LVCR by EF was present in 536 (59.3%) and absent in 368 (40.7%) pts. LVCR by Force was present in 200 pts (22.1%) and absent in 704 pts (77.9%) pts. The overall concordance between LVCR assessed by EF and Force was 538 pts (89.6%) with presence of CR by EF and not by Force being the most frequent source of discrepant result in 336 pts.  In the long-term follow up, 52 pts experienced events: 0 all-cause death, 3 acute myocardial infarctions, 5 cerebrovascular accidents and 44 for hospitalization due to cardiovascular causes. Lack of LVCR based on EF identified patients at higher risk (see Figure) but Force-based LVCR allowed to further separate  patients with EF-based LVCR  (n = 536) into a lower risk with (n = 200, event rate 2%) and higher risk subgroup without Force-based LVCR  (n= 336, event rate 5.3 %, p<.01 vs subgroup with Force-based LVCR)  Cox Regression model identified Force-based LVCR  was the only predictor of events (HR: 3.22, 95% CI 1.83-5.6, p < 0.001). Conclusions. In patients with negative SE for RWMA, the evaluation of LVCR based on EF allows a better stratification of outcome, which is further refined by addition of Force-based LVCR, especially useful in the subset with LVCR by EF not confirmed by Force. Force-based LVCR allowed to identify a subgroup of worse long-term prognosis outperforming EF-based LVCR. Abstract Figure. LVCR by EF and Event Free Survival