Assessment of the Prognostic Value of MRI Left Ventricular Global Function Index (LVGFI) in Patients With End-Stage Renal Disease Under Maintenance Dialysis.

BACKGROUND: Left ventricular global function index (LVGFI) integrates LV volumetric and functional parameters. In patients with end-stage renal disease (ESRD), cardiac injury manifests as LV hypertrophy and dysfunction. However, the prognostic value of LVGFI in this population remains unclear. PURPOSE: To investigate the association of LVGFI with major adverse cardiac events (MACE) in patients with ESRD. STUDY TYPE: Prospective. POPULATION: One hundred fifty-eight ESRD patients (mean age: 54.1 ± 14.4 years; 105 male) on maintenance dialysis. FILED STRENGTH/SEQUENCE: 3.0 T, balanced steady-state free precession (bSSFP) cine and modified Look-Locker inversion recovery (MOLLI) sequences. ASSESSMENT: LV volumetric and functional parameters were determined from bSSFP images. LVGFI was calculated as the ratio of stroke volume to global volume and native T1 was determined from MOLLI T1 maps. MACE was recorded on follow up. Models were developed to predict MACE from conventional risk factors combined with LVGFI, GLS, native T1, and LV mass index (LVMI), respectively. Subgroup analyses were further performed in participants with LVEF above median. STATISTICAL TESTS: Cox proportional hazard regression and log-rank test were used to investigate the association between LVGFI and MACE. The predictive models were evaluated and compared using Harrell's C-statistics and DeLong tests. A P value <0.05 was considered statistically significant. RESULTS: Thirty-four MACE occurred during the median follow-up period of 26 months. The hazard of MACE increased by 114% for each 10% decrease in LVGFI in univariable analysis. The predictive model consisting of LVGFI (C-statistic: 0.724) had significantly better predictive performance than the others (all P < 0.001). These results were consistent in patients (N = 79) with LVEF > median (63.54%). DATA CONCLUSION: LVGFI is a novel marker for MACE risk stratification in patients with ESRD and was better able to predict MACE than native T1 mapping and GLS. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 3.

Ventricular global function index is associated with clinical outcomes in pediatric pulmonary hypertension.

BACKGROUND: Multiple right ventricular (RV) metrics have prognostic value in pulmonary hypertension (PH). A cardiac magnetic resonance imaging (CMR) derived global ventricular function index (GFI) provided improved prediction of composite adverse outcome (CAO) in adults with atherosclerosis. GFI has not yet been explored in a PH population. We explored the feasibility of GFI as a predictor of CAO in a pediatric PH population. METHODS: Two center retrospective chart review identified pediatric PH patients undergoing CMR from Jan 2005-June 2021. GFI, defined as the ratio of the stroke volume to the sum of mean ventricular cavity and myocardial volume, was calculated for each patient. CAO was defined as death, lung transplant, Potts shunt, or parenteral prostacyclin initiation after CMR. Cox proportional hazards regression was used to estimate associations and assess model performance between CMR parameters and CAO. RESULTS: The cohort comprised 89 patients (54% female, 84% World Health Organization (WHO) Group 1; 70% WHO-FC ≤ 2; and 27% on parenteral prostacyclin). Median age at CMR was 12 years (IQR 8.1-17). Twenty-one (24%) patients experienced CAO during median follow up of 1.5 years. CAO cohort had higher indexed RV volumes (end systolic-145 vs 99 mL/m2, p = 0.003; end diastolic-89 vs 46 mL/m2, p = 0.004) and mass (37 vs 24 gm/m2, p = 0.003), but lower ejection fraction (EF) (42 vs 51%, p < 0.001) and GFI (40 vs 52%, p < 0.001). Higher indexed RV volumes (hazard ratios [HR] 1.01, CI 1.01-1.02), lower RV EF (HR 1.09, CI 1.05-1.12) and lower RV GFI (HR 1.09, CI 1.05-1.11) were associated with increased risk of CAO. In survival analysis, patients with RV GFI < 43% demonstrated decreased event-free survival and increased hazard of CAO compared to those with RV GFI ≥ 43%. In multivariable models, inclusion of GFI provided improved prediction of CAO compared to models incorporating ventricular volumes, mass or EF. CONCLUSIONS: RV GFI was associated with CAO in this cohort, and inclusion in multivariable models had increased predictive value compared to RVEF. GFI uses readily available CMR data without additional post-processing and may provide additional prognostic value in pediatric PH patients beyond traditional CMR markers.

Reference values of cardiac volumes, dimensions, and new functional parameters by MR: A multicenter, multivendor study.

PURPOSE: To define reference values of cardiac volumes, dimensions, and new morpho-functional parameters normalized for age, gender, and body surface area by cine-bSSFP (balanced steady-state free-precession) magnetic resonance (MR). MATERIALS AND METHODS: We enrolled 308 healthy subjects subdivided by gender and by six age classes: class I, >15-20 years; class II, >20-30 years; class III, >30-40 years; class IV, >40-50 years; class V, >50-60 years; and class VI >60 years. Dimensional, volumetric and morpho-functional parameters of the left (LV) and right (RV) ventricles were measured using cine-bSSFP MRI at 1.5T. RESULTS: The LV and RV end-diastolic volume indexes (EDVi) were inversely related to age (P < 0.0001 r = -0.34 and P < 0.0001 r = -0.37, respectively). In addition, the LV mass index decreased with age (P = 0.0004, r = -0.21). The LV longitudinal shortening was not significantly different among groups: ≥15% in all populations (95% confidence interval [CI]: 16-31). The sphericity index measured in end-diastole was higher in females than in males (P < 0.03): the upper limit was 40% for males and 42% for females. The normality cutoff of LV global function index was ≥33% in males and ≥35% in females. The end-diastolic volume (EDV) of RV and LV was balanced (RV/LV ratio 0.85-1.15) without differences in the population. The LV EDV/mass was 1.0-1.8 in males and 1.0-2.1 in females. CONCLUSION: This study provides potential age- and gender-specific reference. LEVEL OF EVIDENCE: 2 J. Magn. Reson. Imaging 2017;45:1055-1067.

Left ventricular global function index is associated with myocardial iron overload and heart failure in thalassemia major patients.

PURPOSE: The left ventricular global function index (LVGFI) is a comprehensive marker of cardiac performance, integrating LV morphology with global function. We explored the cross-sectional association of LVGFI with myocardial iron overload (MIO), LV ejection fraction (LVEF), myocardial fibrosis, and heart failure (HF) in ß-thalassemia major (TM) patients. METHODS: We considered 1352 adult TM patients (708 females, 32.79 ± 7.16years) enrolled in the Myocardial Iron Overload in Thalassemia Network and 112 healthy subjects (50 females, 32.09 ± 6.08years). LVGFI and LVEF were assessed by cine images and MIO by multislice multiecho T2* technique. Replacement myocardial fibrosis was detected by late gadolinium enhancement technique. RESULTS: LVGFI and LVEF were significantly lower in patients with significant MIO (global heart T2*<20ms) than in patients without MIO and in healthy subjects but were comparable between TM patients without MIO and healthy subjects. In TM, LVGFI was significantly associated with LVEF (R = 0.733; p < 0.0001). Global heart T2* values were significantly associated with both LVGFI and LVEF, but the correlation with LVGFI was significantly stronger (p = 0.0001). Male sex, diabetes mellitus, significant MIO, and replacement myocardial fibrosis were the strongest predictors of LVGFI. Eighty-six patients had a history of HF and showed significantly lower global heart T2* values, LVEF, and LVGFI than HF-free patients. A LVGFI ≤ 44.9% predicted the presence of HF. The LVGFI showed a diagnostic performance superior to that of LVEF (area under the curve: 0.67 vs. 0.62; p = 0.039). CONCLUSION: In TM patients the LVGFI correlates with MIO and provides incremental diagnostic value for HF detection compared with LVEF.

Association Between Left Ventricular Global Function Index and Outcomes in Patients With Dilated Cardiomyopathy.

Purpose: Left ventricular global function index (LVGFI) assessed using cardiac magnetic resonance (CMR) seems promising in the prediction of clinical outcomes. However, the role of the LVGFI is uncertain in patients with heart failure (HF) with dilated cardiomyopathy (DCM). To describe the association of LVGFI and outcomes in patients with DCM, it was hypothesized that LVGFI is associated with decreased major adverse cardiac events (MACEs) in patients with DCM. Materials and Methods: This prospective cohort study was conducted from January 2015 to April 2020 in consecutive patients with DCM who underwent CMR. The association between outcomes and LVGFI was assessed using a multivariable model adjusted with confounders. LVGFI was the primary exposure variable. The long-term outcome was a composite endpoint, including death or heart transplantation. Results: A total of 334 patients (mean age: 55 years) were included in this study. The average of CMR-LVGFI was 16.53%. Over a median follow-up of 565 days, 43 patients reached the composite endpoint. Kaplan-Meier analysis revealed that patients with LVGFI lower than the cutoff values (15.73%) had a higher estimated cumulative incidence of the endpoint compared to those with LVGFI higher than the cutoff values (P = 0.0021). The hazard of MACEs decreased by 38% for each 1 SD increase in LVGFI (hazard ratio 0.62[95%CI 0.43-0.91]) and after adjustment by 46% (HR 0.54 [95%CI 0.32-0.89]). The association was consistent across subgroup analyses. Conclusion: In this study, an increase in CMR-LVGFI was associated with decreasing the long-term risk of MACEs with DCM after adjustment for traditional confounders.

Left Ventricular Global Function Index and the Impact of its Companion Metric.

Left ventricular (LV) global function index (LVGFI) has been introduced as a volume-based composite metric for evaluation of ventricular function. The definition formula combines stroke volume (SV), end-systolic volume (ESV), end-diastolic volume (EDV) and LV mass/density. Being a dimensionless ratio, this new metric has serious limitations which require evaluation at a mathematical and clinical level. Using CMRI in 96 patients we studied LV volumes, various derived metrics and global longitudinal strain (GLS) in order to further characterize LVGFI in three diagnostic groups: acute myocarditis, takotsubo cardiomyopathy and acute myocardial infarction. We also considered the LVGFI companion (C), derived from the quadratic mean. Additional metrics such as ejection fraction (EF), myocardial contraction fraction (MCF) and ventriculo-arterial coupling (VAC), along with their companions (MCFC and VACC) were calculated. All companion metrics (EFC, LVGFIC, MCFC, and VACC) showed sex-specific differences, not clearly reflected by the corresponding ratio-based metrics. LVGFI is mathematically coupled to both EF (with R = 0.86) and VAC (R = 0.87), which observation clarifies why these metrics not only share similar prognostic values but also identical shortcomings. We found that the newly introduced LVGFIC has incremental value compared to the single use of LVGFI, EF, or GLS, when characterizing the three patient groups.

Prognostic value of left ventricular global function index in patients after ST-segment elevation myocardial infarction.

AIMS: The left ventricular global function index (LVGFI) is a novel indicator of left ventricular performance. Its prognostic value in patients after ST-segment elevation myocardial infarction (STEMI) is unknown. We sought to evaluate the prognostic significance of LVGFI measured by cardiovascular magnetic resonance (CMR) imaging after STEMI. METHODS AND RESULTS: Two hundred eligible STEMI patients (56 ± 11 years, 16% female) revascularized by primary percutaneous coronary intervention were followed-up for 3.1 [2-4.1] years for major adverse cardiac events (MACE). MACE was defined as a composite of death, non-fatal myocardial re-infarction, and new congestive heart failure. All patients underwent CMR imaging within 2 [2-4] days after STEMI. Late enhancement and cine images were acquired to assess myocardial injury as well as myocardial function, including LVGFI. Patients suffering a MACE event (n = 20, 10%) had a significantly lower LVGFI (P = 0.001). In Kaplan-Meier analysis, a decreased LVGFI was associated with a reduced MACE-free survival (P < 0.001). Multivariate Cox regression analysis revealed a decreased LVGFI as a predictor for MACE [hazard ratio = 4.79, 95% confidence interval (CI) 1.46-15.67, P = 0.010] after adjusting for microvascular obstruction, left ventricular mass, and multivessel disease. In receiver operating characteristic analysis, LVGFI was a strong predictor for MACE (area under the curve = 0.73, CI 0.61-0.85). However, c-statistics revealed that LVGFI does not provide incremental prognostic information over left ventricular ejection fraction (LVEF) (P = 0.38). CONCLUSION: LVGFI assessed by CMR is a strong predictor of MACE within 3 years after first STEMI. A superior predictive value as compared with LVEF was not found in this study.