Global longitudinal strain predicts cardiovascular events after coronary artery bypass grafting

Artificial intelligence calculated global longitudinal strain and left ventricular ejection fraction predicts cardiac events and all-cause mortality in patients with chest pain

BACKGROUND

Assessment of left ventricular ejection fraction (LVEF) and myocardial deformation with global longitudinal strain (GLS) has shown promise in predicting adverse cardiovascular events. The aim of this study was to evaluate whether artificial intelligence (AI) calculated LVEF and GLS is associated with major adverse cardiac events (MACE) and all-cause mortality in patients presenting with chest pain.

METHODS

We studied 296 patients presenting with chest pain, who underwent transthoracic echocardiography (TTE). Clinical data, downstream clinical investigations and patient outcomes were collected. Resting TTE images underwent AI contouring for automated calculation of LVEF and GLS with Ultromics EchoGo Core 2.0. Regression analysis was performed to identify clinical and AI calculated parameters associated with MACE and all-cause mortality.

RESULTS

During a median follow-up period of 7.8 years (IQR 6.4, 8.8), MACE occurred in 34 (11.5%) patients and all-cause mortality in 60 (20%) patients. AI calculated LVEF (Odds Ratio [OR] .96; 95% CI .93-.99 and .96; 95% CI .93-.99) and GLS (1.11; 95% CI 1.01-1.21 and 1.08; 95% CI 1.00-1.16) were independently associated with MACE and all-cause mortality, respectively. According to Cox proportional hazards, a LVEF < 50% was associated with a 3.7 times MACE and 2.8 times all-cause mortality hazard rate compared to those with a LVEF ≥ 50%. Those with a GLS ≥ 15% was associated with a 2.5 times MACE and 2.3 times all-cause mortality hazard rate compared to those with a GLS ≤ 15.

CONCLUSION

AI calculated resting LVEF and GLS is independently associated with MACE and all-cause mortality in high CVD risk patients. These results may have significant clinical implications through improved risk stratification of patients with chest pain, accelerated workflow of labour-intensive technical measures, and reduced healthcare costs.

Role of Cardiovascular Imaging in Risk Assessment: Recent Advances, Gaps in Evidence, and Future Directions

Optimal risk assessment for primary prevention remains highly challenging. Recent registries have highlighted major discrepancies between guidelines and daily practice. Although guidelines have improved over time and provide updated risk scores, they still fail to identify a significant proportion of at-risk individuals, who then miss out on effective prevention measures until their initial ischemic events. Cardiovascular imaging is progressively assuming an increasingly pivotal role, playing a crucial part in enhancing the meticulous categorization of individuals according to their risk profiles, thus enabling the customization of precise therapeutic strategies for patients with increased cardiovascular risks. For the most part, the current approach to patients with atherosclerotic cardiovascular disease (ASCVD) is homogeneous. However, data from registries (e.g., REACH, CORONOR) and randomized clinical trials (e.g., COMPASS, FOURIER, and ODYSSEY outcomes) highlight heterogeneity in the risks of recurrent ischemic events, which are especially higher in patients with poly-vascular disease and/or multivessel coronary disease. This indicates the need for a more individualized strategy and further research to improve definitions of individual residual risk, with a view of intensifying treatments in the subgroups with very high residual risk. In this narrative review, we discuss advances in cardiovascular imaging, its current place in the guidelines, the gaps in evidence, and perspectives for primary and secondary prevention to improve risk assessment and therapeutic strategies using cardiovascular imaging.

Strain Imaging and Ventricular Arrhythmia

Ventricular arrhythmia is one of the main causes of sudden cardiac death. Hence, identifying patients at risk of ventricular arrhythmias and sudden cardiac death is important but can be challenging. The indication for an implantable cardioverter defibrillator as a primary preventive strategy relies on the left ventricular ejection fraction as a measure of systolic function. However, ejection fraction is flawed by technical constraints and is an indirect measure of systolic function. There has, therefore, been an incentive to identify other markers to optimize the risk prediction of malignant arrhythmias to select proper candidates who could benefit from an implantable cardioverter defibrillator. Speckle-tracking echocardiography allows for a detailed assessment of cardiac mechanics, and strain imaging has repeatedly been shown to be a sensitive technique to identify systolic dysfunction unrecognized by ejection fraction. Several strain measures, including global longitudinal strain, regional strain, and mechanical dispersion, have consequently been proposed as potential markers of ventricular arrhythmias. In this review, we will provide an overview of the potential use of different strain measures in the context of ventricular arrhythmias.

Incremental Prognostic Value of Left Ventricular Longitudinal Strain Over Ejection Fraction in Coronary Artery Bypass Grafting

OBJECTIVES

To evaluate the incremental prognostic value of longitudinal strain over left ventricular ejection fraction (LVEF) after coronary artery bypass grafting (CABG).

DESIGN

Retrospective cohort study.

SETTING

Single tertiary-care center.

PARTICIPANTS

Patients underwent isolated CABG between January 2014 and December 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

There were 999 patients (median age, 65 years, 23.5% female) categorized into 3 groups according to their left ventricular (LV) systolic function status: pEF/pS (preserved LVEF and preserved longitudinal strain, n = 490), pEF/iS (preserved LVEF and impaired longitudinal strain, n = 186), and rEF (reduced LVEF, n = 323). During a median follow-up of 2.7 years, 86 (8.6%) patients had died. The 5-year survival significantly differed in patients with preserved LVEF according to the strain status (pEF/pS v pEF/iS, 90.0% v 84.6%; p = 0.002). After adjusting for potential confounders, the pEF/iS group (adjusted hazard ratio [HR], 2.17; 95% CI, 1.10-4.28; p = 0.03) and the rEF group (adjusted HR, 2.96; 95% CI, 1.46-6.00; p = 0.003) had significantly higher risks for all-cause death compared with the pEF/pS group. The addition of longitudinal strain to LVEF in the prediction model significantly improved its performance (global chi-squared, 105.2 v 110.2; p = 0.03).

CONCLUSIONS

Left ventricular longitudinal strain could differentiate the prognosis after CABG in patients with preserved LVEF and provide significant incremental prognostic value to LVEF.

Right ventricular strain predicts adverse outcomes in patients undergoing coronary artery bypass grafting

Patients undergoing coronary artery bypass grafting (CABG) face an elevated risk of heart failure (HF) and cardiovascular (CV) death. Detailed myocardial tissue analyses of the right ventricle are now possible and may hold prognostic value in these patients. Accordingly, we aimed to evaluate the usefulness of right ventricular (RV) layer-specific RV free wall strain (RVFWS) for predicting HF and/or CV death. Patients undergoing CABG at Gentofte Hospital from 2006 to 2011 with a preoperative echocardiogram underwent RVWFS analysis. RVFWS was obtained by speckle tracking. The outcome was defined as a composite of HF and/or CV death. Cox proportional hazards regression, Harrell's C-statistics, and competing risk regression were used to assess the prognostic value of RVFWS. Of 317 patients, 30 (9.5%) reached the endpoint at a median follow-up of 3.5 years. The mean age was 67 years, 83% were men, and the mean LVEF was 50%. In univariable analyses, endo-RVFWS (HR 1.08, P < 0.001), mid-RVFWS (HR 1.07, P = 0.002), and epi-RVFWS (HR 1.07, P = 0.004, per 1% absolute decrease) were associated with a higher risk of HF or/and CV death. Furthermore, all three layers remained independently associated with the outcome after multivariable adjustment for baseline clinical and echocardiographic measurements. Low endo-RVFWS was associated with a more than threefold increased risk of the outcome (HR = 3.04 (1.45-6.38) P = 0.003). The same was observed for mid-RVFWS (HR = 3.16 (1.45-6.91) P = 0.004), and epi-RVFWS (HR = 3.00 (1.46-6.17) P = 0.003). In patients undergoing CABG, RVFWS assessed by speckle-tracking is a predictor of adverse outcomes.