Left ventricular eccentricity index measured with SPECT myocardial perfusion imaging: An additional parameter of adverse cardiac remodeling

Realistic Aspects of Cardiac Ultrasound in Rats: Practical Tips for Improved Examination

Echocardiography is a reliable and non-invasive method for assessing cardiac structure and function in both clinical and experimental settings, offering valuable insights into disease progression and treatment efficacy. The successful application of echocardiography in murine models of disease has enabled the evaluation of disease severity, drug testing, and continuous monitoring of cardiac function in these animals. However, there is insufficient standardization of echocardiographic measurements for smaller animals. This article aims to address this gap by providing a guide and practical tips for the appropriate acquisition and analysis of echocardiographic parameters in adult rats, which may also be applicable in other small rodents used for scientific purposes, like mice. With advancements in technology, such as ultrahigh-frequency ultrasonic transducers, echocardiography has become a highly sophisticated imaging modality, offering high temporal and spatial resolution imaging, thereby allowing for real-time monitoring of cardiac function throughout the lifespan of small animals. Moreover, it allows the assessment of cardiac complications associated with aging, cancer, diabetes, and obesity, as well as the monitoring of cardiotoxicity induced by therapeutic interventions in preclinical models, providing important information for translational research. Finally, this paper discusses the future directions of cardiac preclinical ultrasound, highlighting the need for continued standardization to advance research and improve clinical outcomes to facilitate early disease detection and the translation of findings into clinical practice.

Prognostic Value of Resting Left Ventricular Sphericity Indexes in Coronary Artery Disease With Preserved Ejection Fraction

BACKGROUND

Adverse left ventricular remodeling is a significant cardiovascular predictor for patients with coronary artery disease and preserved left ventricular ejection fraction (LVEF). However, the remodeling indexes reflecting left ventricular spherization by myocardial perfusion imaging are underexplored.

METHODS AND RESULTS

727 patients (mean age 59.8±13.5 years, 329 women) diagnosed or suspected coronary artery disease with preserved LVEF who underwent resting myocardial perfusion imaging were retrospectively enrolled. The myocardial perfusion imaging findings including the total perfusion deficit and sphericity indexes (shape index (SI) and eccentricity index (EI) obtained from gated (QGS) and non-gated (QPS) images) were collected. Major adverse cardiovascular events (MACE) were followed up for 45.1±22.0 months. All patients were divided into 4 subgroups based on total perfusion deficit at 10% and LVEF at 65%. Univariable comparative analyses were performed in 5 cohorts (all patients and 4 subgroups). Patients who experienced MACE displayed higher SI and/or lower EI (all P<0.05). Kaplan-Meier survival analyses suggested significant differences for SIQPS in all 5 cohorts, for EIQPS and EIQGS in 4 cohorts, and for end-systolic and end-diastolic SIQGS in 3 cohorts (all P<0.05). Multivariate Cox analysis showed that abnormal SI and EI remained statistically significant predictors for MACE after adjusting for total perfusion deficit, LVEF, and other confounding factors.

CONCLUSIONS

For patients diagnosed or suspected of coronary artery disease with preserved or supra-normal LVEF, resting sphericity indexes by myocardial perfusion imaging displayed incremental long-term prognostic value. Among these indicators, SIQPS is particularly promising across different perfusion or preserved functional conditions.

Association of exosomes in patients with compromised myocardial perfusion on functional imaging

BACKGROUND

Exosomes are membrane vesicles that are actively secreted in response to microenvironmental stimuli. In this study, we quantified the amount of exosomes in patients with significant coronary artery disease (CAD) and evaluated its relationship with myocardial perfusion imaging (MPI) results.

METHODS

Patients who underwent both MPI and coronary angiography were recruited. Plasma was collected during angiography, and exosomes were extracted via the precipitation method. The summed stress scores (SSS), summed difference scores, and ventricular functional parameters were calculated from the MPI and compared with the amounts of exosomes and extracted miRNAs.

RESULTS

In total, 115 patients were enrolled (males: 78 %; mean age: 66.6 ± 10.6 years). Those with abnormal SSS according to the MPI had significantly fewer exosomes (p = 0.032). After multivariate analysis, the SSS remained significantly related to the amount of exosomes (p = 0.035). In forty randomly selected samples, miRNA-432-5p and miRNA-382-3p were upregulated in patients with abnormal SSS.

CONCLUSION

Patients with compromised poststress myocardial perfusion on MPI tended to have fewer exosomes in association with CAD-related miRNAs. This is the first study to clarify the fundamental and pathophysiological causes of CAD using radiographic examinations.

Left ventricular shape index and eccentricity index with ECG-gated Nitrogen-13 ammonia PET/CT in patients with myocardial infarction, ischemia, and normal perfusion

BACKGROUND

LV geometry with shape index (SI) and eccentricity index (EI) measured by myocardial perfusion positron emission tomography/computed tomography (PET/CT) may allow the evaluation of left ventricular (LV) adverse remodeling. This first study aims to explore the relationship of SI and EI values acquired by Nitrogen-13 ammonia PET/CT in patients with normal perfusion, ischemia, and myocardial infarction. And evaluate the correlations between the variables of LV geometry, and with the variables of LV function.

METHODS AND RESULTS

One hundred and forty patients who underwent an electrocardiogram (ECG)-gated PET/CT were selected and classified into 4 groups according to ischemia or infarction burden (normal perfusion, mild ischemia, moderate-severe ischemia, and infarction). The variables were automatically retrieved using dedicated software (QPS/QGS; Cedars-Sinai, Los Angeles, CA, USA). On multicomparison analysis (one-way ANOVA and Dunnett's Test), subjects in the infarction group had significant higher values of SI end-diastolic rest (P < 0.001), and stress (P = 0.003), SI end-systolic rest (P = 0.002) and stress (P < 0.001) as well as statistically significant lower values of EI rest (P < 0.001) and stress (P < 0.001) when compared with all other groups. Regarding Pearson correlation, in the infarcted group all the variables of SI and EI were significantly correlated (P < 0.001) with strong correlation coefficients (>0.60). SI end-systolic correlated significantly with the variables of LV function independently of the group of patients (P < 0.05).

CONCLUSIONS

Shape and eccentricity indices differ in patients with myocardial infarction as compared to patients with ischemia or normal perfusion. This encourage further research in their potential for detecting LV adverse remodeling.

Spherization indices measured by resting SPECT improve risk stratification in patients with ischemia with non-obstructive coronary artery disease (INOCA)

BACKGROUND

The prevalence of ischemia with non-obstructive coronary artery disease (INOCA) is substantial, but its risk stratification has been suboptimal. Resting SPECT myocardial perfusion imaging (MPI) could provide useful heart information including spherical indices. We aimed to evaluate the prognostic value of spherical indices in individuals with INOCA.

RESULTS

During a median follow-up of 47.2 ± 20.8 months, 49 (17.2%) patients experienced major adverse cardiac events (MACE). Compared to those without MACE, those with MACE had a higher shape index (SI) (0.60 ± 0.07 vs. 0.58 ± 0.06; P = 0.028) and a lower E2 (eccentricity index calculated by the QPS) (0.81 ± 0.05 vs. 0.83 ± 0.04; P = 0.019). MACE event-free survival analysis revealed significant differences in the SI and E2 among all patients (all log-rank P < 0.01). Multivariate Cox analysis showed abnormal SI (HR: 2.73, 95% CI 1.44-5.18, P = 0.002) and E2 (HR: 1.94, 95% CI 1.08-3.48, P = 0.026) were both independent predictors for MACE when they were put into the same model, respectively. The incorporation of the SI into the baseline model demonstrated a significant improvement in the predictive accuracy for MACEs (P = 0.026), whereas E2 did not exhibit a similar improvement (P > 0.05).

CONCLUSION

For patients with INOCA, spherical indices (especially the SI) were associated with long-term MACE, which could be a preferable indicator for risk stratification and prognostic prediction.

Left ventricular eccentricity index to assess precapillary pulmonary hypertension in dogs

INTRODUCTION

Interventricular septal flattening, frequently present in pulmonary hypertension (PH) can be quantified by the left ventricular eccentricity index (EI) measured at end-diastole (EId), end-systole (EIs) and at maximal septal flattening (EIm). In humans, EI correlates with invasive pulmonary arterial pressure. The aim of this study was to evaluate if EI correlates with parameters of right heart remodeling (RHR) and if EI is a quantitative marker of PH in dogs.

MATERIALS AND METHODS

Left ventricular eccentricity indices were retrospectively measured in four groups (no, mild, moderate and severe PH) with interpretable tricuspid and/or pulmonary regurgitation.

RESULTS

Ninety-seven dogs were included, with no (n = 29), mild (n = 13), moderate (n = 25) and severe (n = 30) PH. The intra- and inter-observer variability for EI measurements ranged from 2 % to 11 %. All EI were significantly elevated in severe compared to no, mild and moderate PH (P < 0.0005). In the moderate group, EIs and EIm were higher compared to the no PH group (P < 0.01). Tricuspid and pulmonary regurgitation pressure gradients and RHR parameters correlated with EId, EIs and EIm in all groups. Optimal cut-off values discriminating moderate and severe PH from no and mild PH were 1.24 (Sensitivity (Se) 60 %; Specificity (Sp) 90 %) for EId, 1.34 (Se 67 %; Sp 95 %) for EIs and 1.37 (Se 76 %; Sp 83 %) for EIm.

CONCLUSIONS

Left ventricular eccentricity indices are reproducible echocardiographic variables increasing with severity of PH. Dogs with moderate and severe PH can be discriminated from dogs with no or mild PH using EIs and EIm.

Integration of ventricular remodeling, synchrony and filling rate parameters to improve the assessment of left ventricular systolic function

INTRODUCTION AND OBJECTIVES

The aim of this study is to assess the relationship between structural, remodeling, synchrony, and systolic left ventricular (LV) function parameters using gated-SPECT myocardial-perfusion-images (gSPECT-MPI). In addition, obtaining the cut-off values for end-diastolic LV-shape-index (EDLVsi), end-systolic LV-shape-index (ESLVsi), ECC (eccentricity-index) and PER, and developing a new index to evaluate different patterns of the LV systolic function.

METHODS

The study was approved by the Hospital's Ethical-Committee (PR[AG]168.2010), and all patients gave their informed consent. We analyzed prospectively 238 patients (age 63.4 ± 13 years) who underwent stress-rest gSPECT-MPI (control-group, n = 148; patients with previous myocardial infarction [MI], n = 90).

RESULTS

In the control group, with regard to remodeling parameters: the end-diastolic-volume-index (EDV) and the ECC were the parameters that influenced the EDLVsi (r2: 0.52, p < 0.001). EDV, PER, men, and the ECC were the parameters (r2: 0.44; p < 0.001) which influenced the ESLVsi. EDLVsi, ESLVsi, LVEF and the stroke-volume were the parameters (r2: 0.62; p < 0.001) which influenced the ECC. With regards to PER: LVEF, heart-rate, bandwidth, and the standard-deviation were the influencing parameters (r2: 0.76; p < 0.001). The cut-off values for EDLVsi, ESLVsi, ECC, and PER were 0.59, 0.42, 0.87, and 3.3, respectively. The PER, the ESLVsi and the bandwidth were the parameters related to patients with previous MI (AUC: 0.89); and they allow the assessment of different patterns of systolic function (PERRS-index: peak-emptying-rate, left ventricular-remodeling and synchrony).

CONCLUSIONS

The remodeling, synchrony and the systolic function parameters of the LV should be interpreted together (PERRS-index). In this way, we obtain different patterns of LV systolic function.

Association of Long Noncoding RNA Expression Signatures with Stress-Induced Myocardial Perfusion Defects

Stress-induced myocardial perfusion defects found in dipyridamole-thallium-201 single-photon emission computed tomography imaging may indicate vascular perfusion abnormalities and risk of obstructive or nonobstructive coronary heart disease. Besides nuclear imaging and subsequent coronary angiography (CAG), no blood test can indicate whether dysregulated homeostasis is associated with stress-induced myocardial perfusion defects. This study investigated the expression signature of long noncoding RNAs (lncRNAs) and genes involved in vascular inflammation and stress response in the blood of patients with stress-induced myocardial perfusion abnormalities (n = 27). The results revealed an expression signature consisting of the upregulation of RMRP (p < 0.01) and downregulations of THRIL (p < 0.01) and HIF1A (p < 0.01) among patients with a positive thallium stress test and no significant coronary artery stenosis within 6 months after baseline treatment. We developed a scoring system based on the expression signatures of RMRP, MIAT, NTT, MALAT1, HSPA1A, and NLRP3 to predict the need for further CAG among patients with moderate-to-significant stress-induced myocardial perfusion defects (area under the receiver operating characteristic curve = 0.963). Therefore, we identified a dysregulated expression profile of lncRNA-based genes in the blood that could be valuable for the early detection of vascular homeostasis imbalance and personalized therapy.

Feasibility of Left Ventricle Lead Implantation in Cardiac Resynchronization Therapy Guided by Gated SPECT and Ventricular Remodeling

BACKGROUND

Cardiac resynchronization therapy (CRT) may benefit patients with advanced heart failure (HF). Abnormal eccentricity index by gated SPECT is related to structural and functional alterations of the left ventricle (LV).

OBJECTIVE

The aim of this study is to evaluate the feasibility of LV lead implantation guided by phase analysis and its relationship to ventricular remodeling.

METHODS

Eighteen patients with indication for CRT underwent myocardial scintigraphy for implant orientation, and eccentricity and ventricular shape parameters were evaluated. P < 0.05 was adopted as statistical significance.

RESULTS

At baseline, most patients were classified as NYHA 3 (n = 12). After CRT, 11 out of 18 patients were reclassified to a lower degree of functional limitation. In addition, patients' quality of life was improved post-CRT. Significant reductions were observed in QRS duration, PR interval, end-diastolic shape index, end-systolic shape index, stroke volume, and myocardial mass post-CRT. The CRT LV lead was positioned concordant, adjacent, and discordant in 11 (61.1%), 5 (27.8%), and 2 (11.1%) patients, respectively. End-systolic and end-diastolic eccentricity demonstrated reverse remodeling post-CRT.

CONCLUSIONS

LV lead implantation in CRT guided by gated SPECT scintigraphy is feasible. The placement of the electrode concordant or adjacent to the last segment to contract was a determinant of reverse remodeling.

Cardiac remodelling in association with left ventricular dyssynchrony and systolic dysfunction in patients with coronary artery disease

BACKGROUND

In patients with coronary artery disease (CAD), ischaemic cardiomyopathy may result in progressive cardiac remodelling and left ventricular (LV) dysfunction. Myocardial perfusion imaging (MPI) can be used to quantify LV size and shape, mechanical dyssynchrony (LVMD) and ejection fraction (EF) as well as myocardial ischaemia and injury extents. We investigated the prevalence of LV remodelling (LVR) in patients with CAD and the relationship between LVR, LVMD and EF.

METHODS

Three hundred twenty-six patients with CAD were evaluated. The EF and end-diastolic volume (EDV) were measured using MPI. LVMD was assessed using phase analysis. LVR was characterised according to LV dilatation or increased shape indices (systolic shape index [SIES] and diastolic shape index [SIED]).

RESULTS

LVR were observed in 41% of CAD patients. EDV, SIES and SIED were larger in patients with LVMD or low EF. After adjustment for age, sex and infarct and ischaemia extents, phase histogram bandwidth correlated with EDV (r = 0.218) and SIES (r = 0.266) and EF correlated with EDV (r = -0.535), SIES (r = -0.554) and SIED (r = -0.217, p < 0.001 for all).

CONCLUSIONS

LVR is frequently seen in patients with CAD and may be detected even before the development of symptomatic heart failure. A large LV volume and a more spherical-shaped LV were associated with LVMD and low EF, highlighting the close relationships between remodelling and systolic dyssynchrony and dysfunction. MPI is useful for assessing LVR by providing information about LV size and shape, which changes from an ellipsoid towards a spherical form in the development of ischaemic cardiomyopathy.

Incremental value of left ventricular shape parameters measured by gated SPECT MPI in predicting the super-response to CRT

BACKGROUND

The purpose of this study was to evaluate the predictive value of left ventricular (LV) shape parameters measured by gated SPECT myocardial perfusion imaging (MPI) in super-responders enrolled in the VISION-CRT trial.

METHODS

One hundred and ninety-nine patients who met standard criteria for CRT from multiple centers were enrolled in this study. End-systolic eccentricity (ESE) and end-diastolic eccentricity (EDE) were measures of LV shape. Super-responders were the patients who had a relative increase in left ventricular ejection fraction (LVEF) ≥ 15%.

RESULTS

Complete data were obtained in 165 patients, and 43.6% of them were classified as super-responders. ESE was an independent predictor of CRT super-responders in univariate (OR 12.59, 95% CI 1.56-101.35, P = .017) and multivariate analysis (OR 35.71, 95% CI 1.66-766.03, P = .006). ESE had an incremental value over significant clinical and SPECT imaging variables, including angiotensin-converting enzyme inhibitors or angiotensin II receptor blocker, coronary artery disease, myocardial infarction, LVEF, end-diastolic volume index, and scar burden (AUC 0.82 vs. 0.80, sensitivity 0.68 vs. 0.65, specificity 0.82 vs. 0.78).

CONCLUSIONS

LV shape parameters derived from gated SPECT MPI have the promise to improve the prediction of the super-response to CRT. Moreover, ESE provides incremental value over existing clinical and nuclear imaging variables.

Quantitation of Poststress Change in Ventricular Morphology Improves Risk Stratification

Shape index and eccentricity index are measures of left ventricular morphology. Although both measures can be quantified with any stress imaging modality, they are not routinely evaluated during clinical interpretation. We assessed their independent associations with major adverse cardiovascular events (MACE), including measures of poststress change in shape index and eccentricity index. Methods: Patients undergoing SPECT myocardial perfusion imaging between 2009 and 2014 from the Registry of Fast Myocardial Perfusion Imaging with Next-Generation SPECT (REFINE SPECT) were studied. Shape index (ratio between the maximum left ventricular diameter in short axis and ventricular length) and eccentricity index (calculated from orthogonal diameters in short axis and length) were calculated in end-diastole at stress and rest. Multivariable analysis was performed to assess independent associations with MACE (death, nonfatal myocardial infarction, unstable angina, or late revascularization). Results: In total, 14,016 patients with a mean age of 64.3 ± 12.2 y (8,469 [60.4%] male were included. MACE occurred in 2,120 patients during a median follow-up of 4.3 y (interquartile range, 3.4-5.7). Rest, stress, and poststress change in shape and eccentricity indices were associated with MACE in unadjusted analyses (all P < 0.001). However, in multivariable models, only poststress change in shape index (adjusted hazard ratio, 1.38; P < 0.001) and eccentricity index (adjusted hazard ratio, 0.80; P = 0.033) remained associated with MACE. Conclusion: Two novel measures, poststress change in shape index and eccentricity index, were independently associated with MACE and improved risk estimation. Changes in ventricular morphology have important prognostic utility and should be included in patient risk estimation after SPECT myocardial perfusion imaging.

Associations of left ventricular shape with left ventricular volumes and functions assessed by ECG-gated SPECT in patients without significant perfusion abnormality

Left ventricular (LV) remodeling often results from conditions with an elevated LV hemodynamic load or after myocardial infarction. The present study was undertaken to investigate the associations of LV shape with LV volumes and functions in patients without significant perfusion abnormality. One hundred and sixty-seven patients without significant perfusion abnormality on ECG-gated SPECT were enrolled. LV ejection fraction (LVEF) was obtained for assessing LV systolic function. Peak filling rate (PFR) and one-third mean filling rate (1/3 MFR) were obtained for assessing LV diastolic function. LV shape index (LVSI) was defined as the ratio of the maximum three-dimensional short- and long-axis LV dimension, and varies from 0 (line) to 1 (sphere). There were 125 male and 42 female patients with a mean age of 70 ± 8 years. End-systolic LVSI was 0.49 ± 0.07 (0.34-0.65). End-systolic LVSI was associated with LV end-diastolic volume (r = 0.51, p < 0.001) and LV end-systolic volume (LVESV) (r = 0.64, p < 0.001), and was inversely associated with LVEF (r = - 0.69, p < 0.001), PFR (r = - 0.45, p < 0.001) and 1/3 MFR (r = - 0.26, p = 0.008). End-systolic LVSI was increased with increased LVESV, and was not any more with LVESV of > 40 ml. Multivariate liner regression analysis showed that age (β = 0.16, p = 0.01), LVESV (β = 0.20, p = 0.03) and LVEF (β = - 0.53, p < 0.001) were significantly associated with end-systolic LVSI. Our data suggest that end-systolic LVSI, a measurement of LV shape, has close correlations with LV volumes and functions in patients without significant perfusion abnormality.

Stress-induced alteration of left ventricular eccentricity: An additional marker of multivessel CAD

BACKGROUND

Abnormal left ventricular (LV) eccentricity index (EI) is a marker of adverse cardiac remodeling. However, the interaction between stress-induced alterations of EI and major cardiac parameters has not been explored. We sought to evaluate the relationship between LV EI and coronary artery disease (CAD) burden in patients submitted to myocardial perfusion imaging (MPI).

METHODS AND RESULTS

Three-hundred and forty-three patients underwent MPI and coronary angiography. LV ejection fraction (EF) and EI were computed from gated stress images as measures of stress-induced functional impairment. One-hundred and thirty-six (40%), 122 (35%), and 85 (25%) patients had normal coronary arteries, single-vessel CAD, and multivessel CAD, respectively. Post-stress EI was lower in patients with multivessel CAD than in those with normal coronary arteries and single-vessel CAD (P = 0.001). This relationship was confirmed only in patients undergoing exercise stress test, where a lower post-stress EI predicted the presence of multivessel CAD (P = 0.039).

CONCLUSIONS

Post-stress alterations of LV EI on MPI may unmask the presence of multivessel CAD.

Evaluation data about accuracy of cadmium-zinc-telluride imaging in detecting single and multivessel coronary artery disease: Focus on gender differences

The data presented in this article are related to the research article entitled: “Accuracy of cadmium-zinc-telluride imaging in detecting single and multivessel coronary artery disease: is there any gender difference?” (Gimelli et al., 2018).

We evaluated gender-related differences in diagnostic accuracy of cadmium-zinc-telluride (CZT) myocardial perfusion imaging (MPI) in detecting single- and multi-vessel coronary artery disease (CAD). We included 1161 consecutive patients with known or suspected coronary artery disease (228, 25% women and 873, 75% men) who had been referred to our laboratory for stress–rest myocardial perfusion imaging (single-day stress–rest low-dose ultrafast protocol). All patients underwent coronary angiography within 30 days; CAD was defined in the presence of a coronary stenosis >70%. Summed stress scores (SSS), summed rest scores (SRS) and summed difference scores (SDS) were obtained. Image quality was graded “good” or better in more than 90% of patients.

Comparison of left ventricular shape by gated SPECT imaging in diabetic and nondiabetic patients with normal myocardial perfusion: A propensity score analysis

BACKGROUND

Diabetes mellitus induces structural and functional cardiac alterations that can result in heart failure. Left ventricular (LV) shape is a dynamic component of cardiac geometry influencing its contractile function. However, few data are available comparing LV shape index in diabetic and nondiabetic patients without overt coronary artery disease after balancing for coronary risk factors.

METHODS

We studied 1168 patients with normal myocardial perfusion and normal LV ejection fraction on stress gated single-photon emission computed tomography (SPECT) imaging. To account for differences in baseline characteristics between diabetic and nondiabetic patients, we created a propensity score-matched cohort considering clinical variables, coronary risk factors, and stress type.

RESULTS

Before matching, diabetic patients were older, had higher prevalence of male gender and coronary risk factors, and higher end-diastolic and end-systolic LV shape index. After matching, all clinical characteristics were comparable between diabetic and nondiabetic patients, but diabetic patients still had higher end-diastolic and end-systolic LV shape index (both P < .001). At multivariable linear regression analysis, diabetes was a strong predictor of end-systolic LV shape index in the overall study population and in the propensity-matched cohort.

CONCLUSIONS

Diabetic patients have higher values of LV shape index compared to nondiabetic patients also after balancing clinical characteristics by propensity score analysis. Shape indexes assessment by gated SPECT may be useful for identifying early LV remodeling in patients with diabetes.