Prognostic value of left ventricular apical four-chamber longitudinal strain after heart valve surgery in real-world practice

Abstract

Background: Left ventricular longitudinal strain is an emerging marker of ventricular systolic function. However, the prognostic value of apical four-chamber longitudinal strain after heart valve surgery in real-world clinical practice is uncertain. The authors investigated whether left ventricular apical four-chamber longitudinal strain measured in real-world practice is helpful for predicting postoperative outcomes in patients undergoing heart valve surgery.

Methods: This observational cohort study was conducted in patients who underwent heart valve surgery between January 2014 and December 2018 at a tertiary hospital in South Korea. The exposure of interest was preoperative left ventricular apical four-chamber longitudinal strain. The primary outcome was postoperative all-cause mortality.

Results: Among 1,773 study patients (median age, 63 years; female, 45.9%), 132 (7.4%) died during a median follow-up of 27.2 months. Preoperative left ventricular apical four-chamber longitudinal strain was significantly associated with all-cause mortality (adjusted hazard ratio, 0.94 per 1% increment in absolute value; 95% CI [0.90, 0.99], P = 0.022), whereas left ventricular ejection fraction (LVEF) was not significantly associated with all-cause mortality (adjusted hazard ratio: 1.01, 95% CI [0.99, 1.03], P = 0.222). Moreover, combining left ventricular apical four-chamber longitudinal strain to the LVEF and conventional prognostic factors enhance the prognostic model for all-cause mortality (P = 0.022).

Conclusions: In patients undergoing heart valve surgery without coronary artery disease, left ventricular apical four-chamber longitudinal strain measured in real-world clinical practice was independently associated with postoperative survival. Left ventricular longitudinal strain measurement may be helpful for outcome prediction after valve surgery.

Keywords: Cardiac surgery; Echocardiography; Heart valve diseases; Morbidity; Mortality; Strain..

Fig. 1.

Relationship between left ventricular longitudinal strain and ejection fraction. A scatter plot showing the relationship between left ventricular longitudinal strain and ejection fraction. Spearman’s coefficient indicated a moderate correlation between left ventricular longitudinal strain and ejection fraction.

Fig. 2.

Adjusted relationship of (A) left ventricular longitudinal strain, (B) LVEF with all-cause mortality, and (C) incremental value of left ventricular longitudinal strain for predicting all-cause mortality. (A, B) Solid lines represent adjusted hazard ratios and the shaded areas indicate 95% CIs. Left ventricular longitudinal strain of 16.3% and LVEF of 50% were used as references. Hazard ratios were estimated per 1% increase in left ventricular longitudinal strain or LVEF. (C) Bar plots represent the Chi-Square statistics of each model. P values are from the likelihood ratio test to compare the nested models (including conventional risk factors with or without left ventricular longitudinal strain). HR: hazard ratio, CCI: Charlson Comorbidity Index, PHTN: pulmonary hypertension, MS: mitral stenosis, AS: aortic stenosis, TR: tricuspid regurgitation, NYHA class: New York Heart Association Functional Classification, LVEF: left ventricular ejection fraction.

Fig. 3.

Adjusted relationship between (A) left ventricular longitudinal strain, (B) LVEF with operative morbidity, and (C) incremental value of left ventricular longitudinal strain for predicting operative morbidity. (A, B) Solid lines represent the adjusted odds ratios, and the shaded areas indicate the 95% CIs. Left ventricular longitudinal strain of 16.3% and LVEF of 50% were used as references. The odds ratios were estimated per 1% increase in left ventricular longitudinal strain or LVEF. (C) Bar plots represent the Chi-Square statistics of each model. P values are from the likelihood ratio test to compare the nested models (including conventional risk factors with or without left ventricular longitudinal strain). BMI: body mass index, CCI: Charlson Comorbidity Index, PHTN: pulmonary hypertension, Hct: hematocrit, HTN: hypertension, MS: mitral stenosis, MR: mitral regurgitation, AS: aortic stenosis, AR: aortic regurgitation, TR: tricuspid regurgitation, NYHA class: New York Heart Association Functional Classification, LVEF: left ventricular ejection fraction.

Fig. 4.

Subgroup analyses for (A) all-cause mortality and (B) operative morbidity. Dots indicate the (A) adjusted hazard ratio and (B) odds ratio. Horizontal lines represent 95% CI. MR: mitral regurgitation.

Fig. 5.

Kaplan–Meier survival curve according to left ventricular longitudinal strain and LVEF strata. Kaplan–Meier curve for all-cause mortality. Preoperative left ventricular systolic function is categorized into three strata (EF ≥ 50% and left ventricular longitudinal strain ≥ 16.3% vs. EF ≥ 50% and left ventricular longitudinal strain < 16.3% vs. EF < 50%). The median value of left ventricular longitudinal strain (16.3%) was used as the cut-off value. HR: hazard ratio, LVEF: left ventricular ejection fraction.