Left ventricular sphericity index analysis for the prediction of appropriate implantable cardioverter-defibrillator therapy

Pressure-dimension index and left ventricular sphericity index following HeartMate II and HeartMate 3 implantation

AIMS

This study aimed to compare the changes in the left ventricle (LV) and right ventricle (RV) geometry and performance after the implantation of HeartMate II (HMII) and HeartMate 3 (HM3). In addition, we investigated whether the echocardiographic parameters LV sphericity index (LVSI) and the novel pressure-dimension index (PDI) can predict post-operative right ventricular failure (RVF).

METHODS AND RESULTS

Between 2012 and 2020, 46 patients [HMII (n = 22) and HM3 (n = 24)] met the study's criteria and had echocardiography tests pre-operatively, 6 and 12 months post-operatively. The LVSI and PDI were calculated together with the standard LV and RV echocardiographic parameters. The mean follow-up was 24 ± 7 months. In both groups, the LV end-diastolic diameter (LVEDD) significantly decreased 12 months post-operatively compared with the pre-operative values (HMII: 6.4 ± 1.4 cm vs. 5.7 ± 0.9 cm, P = 0.040; HM3: 6.7 ± 1.3 cm vs. 5.5 ± 0.9 cm, P < 0.01, respectively). RV function 12 months post-operatively was better in the HM3 group than in the HMII group, as indicated by a significantly higher RV fractional area change (RVFAC) in the HM3 group than in the HMII group 12 months post-operatively (35 ± 12% vs. 26 ± 16%, P = 0.039), significantly higher tricuspid annular plane systolic excursion (TAPSE) in the HM3 group 12 months post-operatively compared with the HMII group (13.9 ± 1.9 mm vs. 12.0 ± 2.1 mm, P = 0.002), and the tissue Doppler estimated tricuspid annular systolic velocity (TASV) was also significantly higher in the HM3 group 12 months post-operatively compared with the HMII group (11.5 ± 2.7 mm/s vs. 9.9 ± 1.5 mm/s, P = 0.020). The LVSI value was significantly higher 12 months post-operatively in the HMII group than in the HM3 group (1.2 ± 0.4 vs. 0.8 ± 0.2, P = 0.001, respectively), indicating worse geometric changes. The PDI decreased 12 months post-operatively in the HM3-group compared with the baseline (3.4 ± 1.4 mmHg/cm2 vs. 2.0 ± 0.8 mmHg/cm2, P < 0.001). In the univariate and multivariate analyses, only the pre-operative PDI was a predictor of post-operative RVF [odds ratio: 3.84 (95% CI: 1.53-18.16, P = 0.022)]. The area under the curve for pre-operative PDI was 0.912. The 2 year survival was significantly better in the HM3 group (log-rank, P = 0.042).

CONCLUSIONS

The design of HM3 offered better geometrical preservation of the LV and enabled normal PDI values, leading to improved RV function, as indicated by better RVFAC, TAPSE, and TASV values. The use of pre-operative PDI as an additional tool for established risk scores might offer a better pre-operative predictor of RVF.

Prognostic value of cardiovascular magnetic resonance left ventricular volumetry and geometry in patients receiving an implantable cardioverter defibrillator

BACKGROUND

Current indications for implantable cardioverter defibrillator (ICD) implantation for sudden cardiac death prevention rely primarily on left ventricular (LV) ejection fraction (LVEF). Currently, two different contouring methods by cardiovascular magnetic resonance (CMR) are used for LVEF calculation. We evaluated the comparative prognostic value of these two methods in the ICD population, and if measures of LV geometry added predictive value.

METHODS

In this retrospective, 2-center observational cohort study, patients underwent CMR prior to ICD implantation for primary or secondary prevention from January 2005 to December 2018. Two readers, blinded to all clinical and outcome data assessed CMR studies by: (a) including the LV trabeculae and papillary muscles (TPM) (trabeculated endocardial contours), and (b) excluding LV TPM (rounded endocardial contours) from the total LV mass for calculation of LVEF, LV volumes and mass. LV sphericity and sphere-volume indices were also calculated. The primary outcome was a composite of appropriate ICD shocks or death.

RESULTS

Of the 372 consecutive eligible patients, 129 patients (34.7%) had appropriate ICD shock, and 65 (17.5%) died over a median duration follow-up of 61 months (IQR 38-103). LVEF was higher when including TPM versus excluding TPM (36% vs. 31%, p < 0.001). The rate of appropriate ICD shock or all-cause death was higher among patients with lower LVEF both including and excluding TPM (p for trend = 0.019 and 0.004, respectively). In multivariable models adjusting for age, primary prevention, ischemic heart disease and late gadolinium enhancement, both LVEF (HR per 10% including TPM 0.814 [95%CI 0.688-0.962] p = 0.016, vs. HR per 10% excluding TPM 0.780 [95%CI 0.639-0.951] p = 0.014) and LV mass index (HR per 10 g/m2 including TPM 1.099 [95%CI 1.027-1.175] p = 0.006; HR per 10 g/m2 excluding TPM 1.126 [95%CI 1.032-1.228] p = 0.008) had independent prognostic value. Higher LV end-systolic volumes and LV sphericity were significantly associated with increased mortality but showed no added prognostic value.

CONCLUSION

Both CMR post-processing methods showed similar prognostic value and can be used for LVEF assessment. LVEF and indexed LV mass are independent predictors for appropriate ICD shocks and all-cause mortality in the ICD population.

Left Ventricular Sphericity Index is a reproducible bedside echocardiographic measure of geometric change between acute phase Takotsubo's syndrome and acute anterior myocardial infarction

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TS and AMI are separate cardiac conditions with similar clinical presentations.

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TS have a higher LVSI than AMI, indicating a more spherical left ventricle.

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LVSI may be utilised acutely to assist differentiation of acute phase TS and AMI.

Background

Left ventricular sphericity index (LVSI) is a simple, quick and reproducible measure to evaluate LV geometric changes. The aim of our study was to evaluate the utility of LVSI as a rapid discrimination tool in two disease processes; Takotsubo’s Syndrome (TS) and Anterior Myocardial Infarction (AMI), in the absence of significant left ventricular systolic dysfunction.

Methods

Consecutive patients with acute phase TS admitted to our institution (Jan 2013 - Dec 2018) were evaluated (n=66). Patients with a comprehensive two-dimensional transthoracic echocardiogram were included in primary analysis (n=50) and age-matched with a cohort of patients with acute anterior AMI (n=50). Appraisal of demographic, clinical and echocardiographic parameters of patients was undertaken. Biplane LVSI was calculated as an average of the short- and long-axis length in the 4- and 2-chamber apical views.

Results

A total of 50 TS patients (64.3±13.7 years, 18% men) were matched with 50 AMI (62.10±12.84 years, 74% men) patients. There was no significant difference in baseline cardiovascular risk factors other than diabetes mellitus (AMI 34% vs TS 17%, p = 0.034). There was also no difference in LV mass (p=0.10) or LVEF (p=0.52) between the two groups. Interestingly, there was a significant difference in mean LVSI between TS (0.60±0.06) vs AMI (0.52±0.07) (p<0.01) reflecting a more spherical shaped left ventricle in the acute TS group.

Conclusions

LVSI is reflective of geometric changes in the left ventricle and may be helpful as a rapid and reproducible diagnostic tool in differentiating between TS and AMI in the acute phase.