Mechanical dyssynchrony according to validated cut-off values using gated SPECT myocardial perfusion imaging

Effect of left ventricular mechanical dyssynchrony assessed pre-renal transplantation on cardiovascular death post transplantation

BACKGROUND

SPECT myocardial perfusion imaging (MPI) provides an assessment of LV mechanical dyssynchrony (LVMD) which correlates with CVD outcomes in diverse populations including those awaiting renal transplant (RT). The current study examines the association of LVMD on pre-transplant MPI with long-term CVD mortality post RT.

METHODS

We identified consecutive patients who underwent RT at the University of Alabama at Birmingham between 2008 and 2012 from our prospectively collected database. 675 patients in the database underwent MPI and had images amenable for phase analysis. A blinded investigator retrieved the studies and derived LVMD indices including histogram bandwidth (BW), standard deviation (SD), phase peak, phase skewness, and phase kurtosis. The primary outcome was CVD death after RT.

RESULTS

The study cohort had a median age of 54 years, 56% were men, 43% had diabetes, and 7% had prior myocardial infarction. Patients were on dialysis for a median of 3.4 years prior to RT and 34% received living donor transplants. During a median follow-up time after RT of 4.7 years (IQR 3.5 to 6.3 years) 59 patients (9%) succumbed to CVD death. Patients with wider BW, wider SD, lower skewness, and lower kurtosis had an increased risk of CVD death. On multivariate adjustment, BW and skewness remained as independent predictors of CVD deaths.

CONCLUSIONS

LVMD by phase analysis of gated SPECT MPI is associated with increased risk of CVD death after RT. This association is independent of demographics, comorbidities, and traditional findings on MPI and added incremental prognostic information. Assessment of LVMD should be considered for risk stratification in these patients.

ACR Appropriateness Criteria® Dyspnea-Suspected Cardiac Origin (Ischemia Already Excluded): 2021 Update

Dyspnea is the symptom of perceived breathing discomfort and is commonly encountered in a variety of clinical settings. Cardiac etiologies of dyspnea are an important consideration; among these, valvular heart disease (Variant 1), arrhythmia (Variant 2), and pericardial disease (Variant 3) are reviewed in this document. Imaging plays an important role in the clinical assessment of these suspected abnormalities, with usually appropriate procedures including resting transthoracic echocardiography in all three variants, radiography for Variants 1 and 3, MRI heart function and morphology in Variants 2 and 3, and CT heart function and morphology with intravenous contrast for Variant 3. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Mechanical dyssynchrony: How do we measure it, what it means, and what we can do about it

Left ventricular mechanical dyssynchrony (LVMD) is defined by a difference in the timing of mechanical contraction or relaxation between different segments of the left ventricle (LV). Mechanical dyssynchrony is distinct from electrical dyssynchrony as measured by QRS duration and has been of increasing interest due to its association with worse prognosis and potential role in patient selection for cardiac resynchronization therapy (CRT). Although echocardiography is the most used modality to assess LVMD, some limitations apply to this modality. Compared to echo-based modalities, nuclear imaging by gated single-photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) has clear advantages in evaluating systolic and diastolic LVMD. GSPECT MPI can determine systolic and diastolic mechanical dyssynchrony by the variability in the timing in which different LV segments contract or relax, which has prognostic impact in patients with coronary artery disease and heart failure. As such, by targeting mechanical dyssynchrony instead of electrical dyssynchrony, GSPECT MPI can potentially improve patient selection for CRT. So far, few studies have investigated the role of diastolic dyssynchrony, but recent evidence seems to suggest high prevalence and more prognostic impact than previously recognized. In the present review, we provide an oversight of mechanical dyssynchrony.

Mechanical Dyssynchrony for Prediction of the Cardiac Resynchronization Therapy Response in Patients with Dilated Cardiomyopathy

Aim      To evaluate the predictive value of indexes of left ventricular mechanical dyssynchrony (MD) as determined by data of electrocardiogram (ECG)-gated myocardial perfusion scintigraphy (ECG-MPS) for prediction of the efficacy of resynchronization therapy (RT) in patients with chronic heart failure (CHF).Material and methods  This prospective study included 32 patients with nonischemic CHF and standard indications for RT. All patients underwent complete clinical an instrumental examination, including 24-h ECG monitoring and echocardiography (EchoCG). In order to evaluate the left ventricular (LV) myocardial perfusion, contractile function, and MD, myocardial perfusion scintigraphy was performed for all patients at rest prior to RT. In addition to the perfusion defect size at rest and hemodynamic parameters, LV MD was determined. The following indexes were used for analysis of dyssynchronization: phase standard deviation (PSD), phase histogram bandwidth (HBW), and phase histogram asymmetry and steepness. The treatment efficacy was evaluated by the clinical status of patients (clinical condition evaluation scale for CHF patient) and EchoCG at 6 months following RT. The criteria for a positive response to RT were an increase in LV ejection fraction (EF) by 5% and/or a decrease in the LV end-diastolic volume by 15% compared to preoperative values.Results According to ECG-MPS findings, all patients had scintigraphic signs of severe CHF with dilated LV cavity (end-diastolic volume, EDV 246 [217; 269] ml) and also of pronounced mechanical and electrical dyssynchrony. The values of mechanical dyssynchrony were PSD 53 [41; 61], HBW 176 [136; 202], asymmetry 1.62 [1.21; 1.89], and steepness 2.81 [1.21; 3.49]. The QRS duration was 165 [155; 175] msec. Furthermore, the LV perfusion was moderately impaired (perfusion defect size 4 [3; 10] %). Mean follow-up duration after implantation of the resynchronizing device was 6±1.7 mos. According to the selected criteria, 20 (63 %) patients were considered as responders and 12 (37 %) patients as non-responders. Before implantation of the cardiac synchronizing device, responders and non-responders differed only in LV MD (PSD 44 [35; 54] vs. 63 [58; 72]; p=0.0001); HBW 158 [118; 179] vs. 205 [199; 249]; p=0.0001; asymmetry 1.77 [1.62; 2.02] vs. 1.21 [0.93; 1.31]; p=0.0001; steepness 3.03 [2.60; 3.58] vs. 1.21 [0.19; 1.46]; p=0.0001), respectively. A one-factor logistic regression analysis showed that MD values were statistically significant predictors of a positive response to RT. A multi-factor logistic analysis of phase histogram steepness (odds ratio, OR 1.196; 95 % confidence interval, CI 1.04-1.37) and PSD (OR 0.67; 95 % CI 0.47-0.97) were identified as independent predictors for the response to RT. According to results of the ROC analysis, a PSD <55 and a phase histogram steepness >1.54 may predict the effectiveness of RT (AUC= 0.92; р=0.0001).Conclusion      LV MD parameters determined with ECG-MPS allow predicting the effectiveness of RT in patients with nonischemic CHF. In this patient group, high values of standard deviation and low values of phase histogram steepness were independent predictors for the absence of response to RT after 6 mos. of follow-up.

Are there normal values of phase analysis parameters for left ventricular dyssynchrony in patients with no structural cardiomyopathy?: a systematic review

BACKGROUND

ECG-gated single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy combined with phase analysis allows for the assessment of left ventricular dyssynchrony. However, there are several software programs available thereby introducing variability in outcome and normal values. The aim of this systematic review was to evaluate the variability between different programs as currently available in literature with a focus on normal values.

METHODS

A systematic review was performed using the Embase, LILACS and Medline databases looking for articles reporting on normal values of the most used phase analysis parameters. The search resulted in 110 articles from Medline, 349 from Embase and one from LILACS. After exclusion of duplicate articles, 370 documents remained. Of these only 13 were deemed eligible for the systematic review.

RESULTS

Phase SD and bandwidth are the main parameters used in dyssynchrony analysis. Most articles reviewed here used the Emory Cardiac ToolBox (ECTb) to determine the phase analysis parameters values, which varied greatly among the four software tested. The bandwidth and phase SD calculated by the Quantitative Gated SPECT (QGS) tends to be smaller than that calculated by the ECTb. In relation to the bandwidth, ECTb and cardioREPO (cREPO) have higher values than the other software programs. The value of entropy obtained from 4DM is lower than those obtained from QGS and cREPO.

CONCLUSION

We found that normal values of phase analysis can vary among software programs and can be different even when the same software is used.

Feasible Classified Models for Parkinson Disease from 99mTc-TRODAT-1 SPECT Imaging

The neuroimaging techniques such as dopaminergic imaging using Single Photon Emission Computed Tomography (SPECT) with ^99mTc-TRODAT-1 have been employed to detect the stages of Parkinson’s disease (PD). In this retrospective study, a total of 202 ^99mTc-TRODAT-1 SPECT imaging were collected. All of the PD patient cases were separated into mild (HYS Stage 1 to Stage 3) and severe (HYS Stage 4 and Stage 5) PD, according to the Hoehn and Yahr Scale (HYS) standard. A three-dimensional method was used to estimate six features of activity distribution and striatal activity volume in the images. These features were skewness, kurtosis, Cyhelsky’s skewness coefficient, Pearson’s median skewness, dopamine transporter activity volume, and dopamine transporter activity maximum. Finally, the data were modeled using logistic regression (LR) and support vector machine (SVM) for PD classification. The results showed that SVM classifier method produced a higher accuracy than LR. The sensitivity, specificity, PPV, NPV, accuracy, and AUC with SVM method were 0.82, 1.00, 0.84, 0.67, 0.83, and 0.85, respectively. Additionally, the Kappa value was shown to reach 0.68. This claimed that the SVM-based model could provide further reference for PD stage classification in medical diagnosis. In the future, more healthy cases will be expected to clarify the false positive rate in this classification model.

Automated Classification of Severity in Cardiac Dyssynchrony Merging Clinical Data and Mechanical Descriptors

Cardiac resynchronization therapy (CRT) improves functional classification among patients with left ventricle malfunction and ventricular electric conduction disorders. However, a high percentage of subjects under CRT (20%–30%) do not show any improvement. Nonetheless the presence of mechanical contraction dyssynchrony in ventricles has been proposed as an indicator of CRT response. This work proposes an automated classification model of severity in ventricular contraction dyssynchrony. The model includes clinical data such as left ventricular ejection fraction (LVEF), QRS and P-R intervals, and the 3 most significant factors extracted from the factor analysis of dynamic structures applied to a set of equilibrium radionuclide angiography images representing the mechanical behavior of cardiac contraction. A control group of 33 normal volunteers (28 ± 5 years, LVEF of 59.7% ± 5.8%) and a HF group of 42 subjects (53.12 ± 15.05 years, LVEF < 35%) were studied. The proposed classifiers had hit rates of 90%, 50%, and 80% to distinguish between absent, mild, and moderate-severe interventricular dyssynchrony, respectively. For intraventricular dyssynchrony, hit rates of 100%, 50%, and 90% were observed distinguishing between absent, mild, and moderate-severe, respectively. These results seem promising in using this automated method for clinical follow-up of patients undergoing CRT.