Right Ventricular Free Wall Longitudinal Strain by Echocardiography ---- Prognostic Value for All-Cause Mortality and Associations with Left Ventricular Diastolic Dysfunction: The Tromsø7 Study

Abstract

Background: Right ventricular free wall longitudinal strain (RVFWLS) by echocardiography is a relatively new and sensitive right ventricular function assessment index. Limited studies have investigated the association between RVFWLS and left ventricular diastolic dysfunction (LVDD), especially in the general population. Moreover, the updated 2016 guidelines for assessing LVDD by echocardiography have shown poor consistency with previous 2009 guidelines, possibly due to the omission of considering myocardial disease in the assessment. Objective: The main objectives of this thesis were to compare the prognostic value of RVFWLS for all-cause mortality with the key indices of LVDD assessment recommended by the 2016 guidelines and investigate the association of RVFWLS with LVDD grades. Also, we wanted to explore the prevalence of LVDD according to the 2016 guidelines with consideration of myocardial disease. <p>

<p>Method: A total of 1147 participants aged ≥40 years from the seventh survey of the population-based Tromsø Study were included. The endpoint was all-cause death. Cox regression models were generated to compare the predictive values of RVFWLS and the key indices of LVDD (left atrial volume index, average e’ velocity, average E/e’, tricuspid regurgitation velocity>2.8m/s). We evaluated the prevalence of LVDD based on 2016 guidelines with consideration of myocardial disease, which was defined as left ventricular hypertrophy. The association between RVFWLS and LVDD grades was evaluated using multivariate linear regression. <p>

<p>Results: During a median follow-up of 6.6 years, 52 subjects (4.5%) died. RVFWLS showed no significant effect on all-cause mortality. Average e’ and E/e’ ratio remained independent predictors after adjusting for clinical and echocardiographic covariates. The prevalence of LVDD was higher when considering myocardial disease based on the 2016 guidelines, compared to not considering it (45.9% vs 23.6%). This effect was particularly pronounced among individuals with normal left ventricular ejection fraction (LVEF ≥50%). RVFWLS increased independently of age and sex in LVDD groups (grade 1, 2/3) compared to the normal left ventricular diastolic function group (grade 0). <p>

<p>Conclusion: Average e’ and E/e’ ratio showed independent associations with all-cause death, while RVFWLS did not exhibit a significant association, which may be mainly due to insufficient statistical power. The omission of considering myocardial disease may attribute to the inconsistency observed between the 2016 and 2009 guidelines for LVDD assessment. The right ventricular function determined by RVFWLS is altered when LVDD occurred even in the early stage.