Ventricular Resynchronization

Myocardial Perfusion SPECT Imaging Radiomic Features and Machine Learning Algorithms for Cardiac Contractile Pattern Recognition

A U-shaped contraction pattern was shown to be associated with a better Cardiac resynchronization therapy (CRT) response. The main goal of this study is to automatically recognize left ventricular contractile patterns using machine learning algorithms trained on conventional quantitative features (ConQuaFea) and radiomic features extracted from Gated single-photon emission computed tomography myocardial perfusion imaging (GSPECT MPI). Among 98 patients with standard resting GSPECT MPI included in this study, 29 received CRT therapy and 69 did not (also had CRT inclusion criteria but did not receive treatment yet at the time of data collection, or refused treatment). A total of 69 non-CRT patients were employed for training, and the 29 were employed for testing. The models were built utilizing features from three distinct feature sets (ConQuaFea, radiomics, and ConQuaFea + radiomics (combined)), which were chosen using Recursive feature elimination (RFE) feature selection (FS), and then trained using seven different machine learning (ML) classifiers. In addition, CRT outcome prediction was assessed by different treatment inclusion criteria as the study's final phase. The MLP classifier had the highest performance among ConQuaFea models (AUC, SEN, SPE = 0.80, 0.85, 0.76). RF achieved the best performance in terms of AUC, SEN, and SPE with values of 0.65, 0.62, and 0.68, respectively, among radiomic models. GB and RF approaches achieved the best AUC, SEN, and SPE values of 0.78, 0.92, and 0.63 and 0.74, 0.93, and 0.56, respectively, among the combined models. A promising outcome was obtained when using radiomic and ConQuaFea from GSPECT MPI to detect left ventricular contractile patterns by machine learning.

Reproducibility of global LV function and dyssynchrony parameters derived from phase analysis of gated myocardial perfusion SPECT: A multicenter comparison with core laboratory setting

BACKGROUND

Gated myocardial perfusion scintigraphy (GMPS) phase analysis is an important tool to investigate the physiology of left ventricular (LV) dyssynchrony. We aimed to test the performance of GMPS LV function and phase analysis in different clinical settings and on a diverse population.

METHODS

This is a post hoc analysis of a prospective, non-randomized, multinational, multicenter cohort study. Clinical evaluation and GMPS prior to cardiac resynchronization therapy (CRT)(baseline) and 6-month post CRT (follow-up) were done. LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV), LV ejection fraction (LVEF), LV phase standard deviation (LVPSD), and percentage of left ventricle non-viable (PLVNV) were obtained by 10 centers and compared to the core lab.

RESULTS

276 GMPS studies had all data available from individual sites and from core lab. There were no statistically significant differences between all variables except for LVPSD. When subjects with no mechanical dyssynchrony were excluded, LVPSD difference became non-significant. LVESV, LVEF, LVPSD and PLVNV had strong correlation in site against core lab comparison. Bland-Altman plots demonstrated good agreement.

CONCLUSIONS

The presented correlation and agreement of LV function and dyssynchrony analysis over different sites with a diverse sample corroborate the strength of GMPS in the management of heart failure in clinical practice.

Comparison of Speckle Tracking Echocardiography During Different Pacing Modalities for Cardiac Resynchronization Therapy Response Prediction

Background: The aim of this study was to evaluate left ventricular mechanical activation pattern by speckle tracking echocardiography (STE) as a predictor of response to cardiac resynchronization therapy (CRT) in patients with heart failure. Methods: Echocardiography was performed during no pacing, right ventricular pacing (RVP), biventricular pacing (BVP) and multipolar pacing (MPP) immediately after CRT implantation in 16 patients at a single centre. Seven patients were diagnosed as responders and 9 patients as non-responders after 6 months of standard CRT pacing. All had adequate short axis views, and 1 CRT responder and 2 CRT non-responders had limited longitudinal views. Results: Longitudinal and circumferential global strain (GS) and global strain rate (GSR) or their change analysis, did not yield any CRT response prediction. However, the longitudinal BVP/RVP GS ratio was significantly higher in the responder group (1.32 ± 0.2%, 2.0 ± 0.4% and 1.9 ± 0.4%), compared with the non-responder group (1.06 ± 0.2%, 1.1 ± 0.4% and 1.2 ± 0.4%) in the apical two-chamber, APLAX and four-chamber views, respectively. Similarly, the longitudinal BVP/RVP GSR at active systolic phase (GSRs) was significantly higher in the responder group (1.9 ± 0.9% and 1.7 ± 0.4%) compared with the non-responder group (1.0 ± 0.4% and 1.1 ± 0.2%) in the apical APLAX and four-chamber views, respectively. Measurements of the strain delay index showed predictive power regarding CRT response in non-paced patients. Conclusion: Post implantation, longitudinal BVP/RVP GS and GSRs ratios of 1.4% and above may be useful as a CRT response prediction tool. Furthermore, our findings support the usefulness of strain delay index prior to CRT implantation in non-paced patients.

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.

Device-Based Solutions to Improve Cardiac Physiology and Hemodynamics in Heart Failure With Preserved Ejection Fraction

Characterized by a rapidly increasing prevalence, elevated mortality and rehospitalization rates, and inadequacy of pharmaceutical therapies, heart failure with preserved ejection fraction (HFpEF) has motivated the widespread development of device-based solutions. HFpEF is a multifactorial disease of various etiologies and phenotypes, distinguished by diminished ventricular compliance, diastolic dysfunction, and symptoms of heart failure despite a normal ejection performance; these symptoms include pulmonary hypertension, limited cardiac reserve, autonomic imbalance, and exercise intolerance. Several types of atrial shunts, left ventricular expanders, stimulation-based therapies, and mechanical circulatory support devices are currently under development aiming to target one or more of these symptoms by addressing the associated mechanical or hemodynamic hallmarks. Although the majority of these solutions have shown promising results in clinical or preclinical studies, no device-based therapy has yet been approved for the treatment of patients with HFpEF. The purpose of this review is to discuss the rationale behind each of these devices and the findings from the initial testing phases, as well as the limitations and challenges associated with their clinical translation.

Value of intraventricular dyssynchrony assessment by gated-SPECT myocardial perfusion imaging in the management of heart failure patients undergoing cardiac resynchronization therapy (VISION-CRT)

BACKGROUND

Placing the left ventricular (LV) lead in a viable segment with the latest mechanical activation (vSOLA) may be associated with optimal cardiac resynchronization therapy (CRT) response. We assessed the role of gated SPECT myocardial perfusion imaging (gSPECT MPI) in predicting clinical outcomes at 6 months in patients submitted to CRT.

METHODS

Ten centers from 8 countries enrolled 195 consecutive patients. All underwent gSPECT MPI before and 6 months after CRT. The procedure was performed as per current guidelines, the operators being unaware of gSPECT MPI results. Regional LV dyssynchrony (Phase SD) and vSOLA were automatically determined using a 17 segment model. The lead was considered on-target if placed in vSOLA. The primary outcome was improvement in ≥1 of the following: ≥1 NYHA class, left ventricular ejection fraction (LVEF) by ≥5%, reduction in end-systolic volume by ≥15%, and ≥5 points in Minnesota Living With Heart Failure Questionnaire (MLHFQ).

RESULTS

Sixteen patients died before the follow-up gSPECT MPI. The primary outcome occurred in 152 out of 179 (84.9%) cases. Mean change in LV phase standard deviation (PSD) at 6 months was 10.5°. Baseline dyssynchrony was not associated with the primary outcome. However, change in LV PSD from baseline was associated with the primary outcome (OR 1.04, 95% CI 1.01-1.07, P = .007). Change in LV PSD had an AUC of 0.78 (0.66-0.90) for the primary outcome. Improvement in LV PSD of 4° resulted in the highest positive likelihood ratio of 7.4 for a favorable outcome. In 23% of the patients, the CRT lead was placed in the vSOLA, and in 42% in either this segment or in a segment within 10° of it. On-target lead placement was not significantly associated with the primary outcome (OR 1.53, 95% CI 0.71-3.28).

CONCLUSION

LV dyssynchrony improvement by gSPECT MPI, but not on-target lead placement, predicts clinical outcomes in patients undergoing CRT.

Cardiac resynchronization therapy for the failing systemic right ventricle: A systematic review

Patients with a systemic right ventricle (SRV) are at high risk for development of heart failure early in life. An SRV is encountered in patients with congenitally corrected transposition of the great arteries (CCTGA) or dextro-transposition of the great arteries (DTGA) with previous atrial switch repair (Mustard or Senning procedure). Progressive heart failure is one of the leading cause of mortality in these patients. Therefore, cardiac resynchronization therapy (CRT) has gained increasing momentum for use in this challenging congenital heart disease (CHD) population. However, current guidelines differ in recommendations for CRT in patients with an SRV as evidence supporting CRT has thus far only been described in case reports and retrospectively in relatively small study populations. In fact, the European Society of Cardiology Guideline for the management of grown-up congenital heart disease consider CRT to be 'experimental' in this population. This systematic review critically summarizes current literature on CRT in SRV patients and provides future perspectives for further research in this challenging and growing CHD population.

Deep Natural Language Processing to Identify Symptom Documentation in Clinical Notes for Patients With Heart Failure Undergoing Cardiac Resynchronization Therapy

CONTEXT

Clinicians lack reliable methods to predict which patients with congestive heart failure (CHF) will benefit from cardiac resynchronization therapy (CRT). Symptom burden may help to predict response, but this information is buried in free-text clinical notes. Natural language processing (NLP) may identify symptoms recorded in the electronic health record and thereby enable this information to inform clinical decisions about the appropriateness of CRT.

OBJECTIVES

To develop, train, and test a deep NLP model that identifies documented symptoms in patients with CHF receiving CRT.

METHODS

We identified a random sample of clinical notes from a cohort of patients with CHF who later received CRT. Investigators labeled documented symptoms as present, absent, and context dependent (pathologic depending on the clinical situation). The algorithm was trained on 80% and fine-tuned parameters on 10% of the notes. We tested the model on the remaining 10%. We compared the model's performance to investigators' annotations using accuracy, precision (positive predictive value), recall (sensitivity), and F1 score (a combined measure of precision and recall).

RESULTS

Investigators annotated 154 notes (352,157 words) and identified 1340 present, 1300 absent, and 221 context-dependent symptoms. In the test set of 15 notes (35,467 words), the model's accuracy was 99.4% and recall was 66.8%. Precision was 77.6%, and overall F1 score was 71.8. F1 scores for present (70.8) and absent (74.7) symptoms were higher than that for context-dependent symptoms (48.3).

CONCLUSION

A deep NLP algorithm can be trained to capture symptoms in patients with CHF who received CRT with promising precision and recall.

Intraventricular synchronism assessment by gated-SPECT myocardial perfusion imaging in cardiac resynchronization therapy. Does cardiomyopathy type influence results?

Purpose

To analyze the evolution post-cardiac resynchronization therapy (CRT) in left ventricular non-compaction (LVNC) cardiomyopathy (CM) patients compared to other types of CM, according to clinical and functional variables, by using gated-SPECT myocardial perfusion imaging (MPI).

Methods

Ninety-three patients (60 ± 11 years, 28% women) referred for pre-CRT assessment were studied and divided into three groups: 1 (non-ischemic CM with LVNC, 11 patients), 2 (ischemic CM, 28 patients), and 3 (non-ischemic CM, 53 patients). All were studied by a ^99mTc-MIBI gated-SPECT MPI at rest pre-CRT implantation and 6 ± 1 months after, including intraventricular dyssynchrony assessment by phase analysis. Quality of life was measured by the Minnesota Living with Heart Failure Questionnaire (MLHFQ).

Results

No differences in sex, atherosclerotic risk factors other than smoking habit, and MLHFQ results were found among groups. LVNC CM patients were younger, with greater QRS width and lower left ventricular ejection fraction (LVEF) at baseline, but the differences were not significant. No significant differences were found at baseline regarding ventricular function, although end-systolic volume was slightly higher in LVNC CM patients. Mean SRS was significantly higher (p < 0.0001) in ischemic patients (14.9) versus non-ischemic ones (8.7 in group 1 and 9 in group 2). At baseline, LVNC CM patients were significantly more dyssynchronous: Their phase standard deviation (PSD) was higher (89.5° ± 14.2°) versus groups 2 (65.2° ± 23.3°) and 3 (69.7° ± 21.7°), p = 0.007. Although the quality of life significantly improved in all groups, non-ischemic patients (with or without LVNC) showed a higher LVEF increase and volumes reduction at 6 months post-CRT. Dyssynchrony reduced post-CRT in all groups. Nevertheless, those more dyssynchronous at baseline (LVNC CM) exhibited the most significant intraventricular synchronism improvement: PSD was reduced from 89.5° ± 14.2° at baseline to 63.7° ± 20.5° post-CRT (p = 0.028). Six months post-CRT, 89% of patients were responders: 11 (100%) of those with LVNC CM, 25 (86%) of those with ischemic CM, and 47 (89%) of patients with non-ischemic CM. No patient with LVNC CM had adverse events during the follow-up.

Conclusion

CRT contributes to a marked improvement in non-ischemic CM patients with non-compaction myocardium. Phase analysis in gated-SPECT MPI is a valuable tool to assess the response to CRT.

Yield of left ventricular dyssynchrony by gated SPECT MPI in patients with heart failure prior to implantable cardioverter-defibrillator or cardiac resynchronization therapy with a defibrillator: Characteristics and prediction of cardiac outcome

BACKGROUND

Mechanical left ventricular dyssynchrony (MLVD) might contribute in the therapeutic decision-making in patients with heart failure (HF) prior to cardiac resynchronization therapy (CRT). Our aim was to assess MLVD in patients with HF prior to implantable cardioverter-defibrillator (ICD) compared to patients with CRT-D.

METHODS

In a prospective study, patients with LVEF ≤ 35% who were scheduled for ICD or CRT-D, underwent gated SPECT myocardial perfusion imaging with technetium 99m sestamibi within 3 months prior procedure. MLVD was measured by phase analysis.

RESULTS

The study cohort consisted of 143 patients, 71 with ICD and 72 with CRT-D. Age 68.3 ± 11 and LVEF 24 ± 6%. Phase standard deviation (SD) was 62.5 ± 18 and 59.7 ± 20 (P = NS), respectively. During follow-up of 23.7 ± 12.1 months, there were 10 vs 14 cardiac death in ICD and CRT-D, respectively (P = NS), hospitalization for HF, in 34 vs 53 (P < .001). In multivariate analysis, Phase SD was the independent predictor for cardiac death [HR 2.66 (95% CI 1.046-6.768), P = .04]. Kaplan-Meier curves of phase SD of 60° significantly identified ICD patients with and without cardiac deaths and hospitalization for HF exacerbation.

CONCLUSIONS

MLVD by phase SD can identify patients with cardiac events and predict cardiac death in patients treated with ICD.

Acute contractile recovery extent during biventricular pacing is not associated with follow-up in patients undergoing resynchronization

Background

It has been reported that contractility, as assessed using dobutamine infusion, is independently associated with reverse remodeling after CRT. Controversy, however, exists about the capacity of this approach to predict a long-term clinical response. This study's purpose was to assess whether long-term CRT clinical effects can be predicted according to acute inotropic response induced by biventricular stimulation (CRT on), as compared with AAI–VVI right stimulation pacing mode (CRT off), quantified at the time of implantation.

Methods

In 98 patients (ejection fraction 29 ± 10%), acute changes in left ventricular (LV) elastance (Ees), arterial elastance (Ea), and Ees/Ea, as assessed from slope changes of the force–frequency relation obtained when the heart rate increased, and also assessed while measuring triplane LV volumes and continuous noninvasive blood pressure, were related to death or rehospitalization during a 3-year follow-up. Other covariances tested were age, gender, disease etiology, QRS duration, amount of mitral regurgitation, LV diastolic volume, ejection fraction, and the degree of asynchrony and longitudinal strain at baseline.

Results

There was a marked increment in the Ees slope with CRT (interaction P = 0.004), no Ea change, and modest Ees/Ea increase (interaction P < 0.05). In Cox analysis, however, neither slope changes nor baseline values of Ees, Ea, and Ees/Ea were associated with long-term follow-up. Only ventricular diastolic volume (direct relation P = 0.002) and QRS duration (inverse relation P = 0.009) predicted death/rehospitalization.

Conclusions

Acute contractile recovery in CRT patients is not associated with 3 years prognosis. Instead, death or rehospitalization can be predicted from QRS duration and LV diastolic volume at baseline.

A New MRI-Based Model of Heart Function with Coupled Hemodynamics and Application to Normal and Diseased Canine Left Ventricles

A methodology for the simulation of heart function that combines an MRI-based model of cardiac electromechanics (CE) with a Navier–Stokes-based hemodynamics model is presented. The CE model consists of two coupled components that simulate the electrical and the mechanical functions of the heart. Accurate representations of ventricular geometry and fiber orientations are constructed from the structural magnetic resonance and the diffusion tensor MR images, respectively. The deformation of the ventricle obtained from the electromechanical model serves as input to the hemodynamics model in this one-way coupled approach via imposed kinematic wall velocity boundary conditions and at the same time, governs the blood flow into and out of the ventricular volume. The time-dependent endocardial surfaces are registered using a diffeomorphic mapping algorithm, while the intraventricular blood flow patterns are simulated using a sharp-interface immersed boundary method-based flow solver. The utility of the combined heart-function model is demonstrated by comparing the hemodynamic characteristics of a normal canine heart beating in sinus rhythm against that of the dyssynchronously beating failing heart. We also discuss the potential of coupled CE and hemodynamics models for various clinical applications.

Left Bundle Branch Block Negatively Affects Coronary Flow Velocity Reserve and Myocardial Contractile Reserve in Nonischemic Dilated Cardiomyopathy

BACKGROUND

Coronary flow velocity reserve (CFVR) of the left anterior descending coronary artery (LAD) and myocardial contractile reserve are often impaired in nonischemic dilated cardiomyopathy (DCM). Whether they are affected by the presence of left bundle branch block (LBBB) remains unaddressed. The aim of the study was to investigate how LBBB influences CFVR of the LAD and myocardial contractile reserve in patients with DCM.

METHODS

One hundred eighty-one patients with DCM (116 men; mean age, 63 ± 12 years) underwent high-dose dipyridamole (0.84 mg/kg over 6 min) stress echocardiography with CFVR evaluation of the LAD by Doppler. All patients had ejection fractions < 40% (mean, 31 ± 8%) and angiographically normal or near normal coronary arteries. CFVR was defined as the ratio between hyperemic peak and basal peak diastolic coronary flow velocities. CFVR > 2.0 was considered normal. Inotropic reserve was defined as rest-stress variation in wall motion score index ≥ 0.20. This was a prospective analysis of an unselected sample consecutively enrolled and retrospectively selected.

RESULTS

The study group was separated on the basis of presence (n = 122) or absence (n = 59) of LBBB. Patients with LBBB were older (64 ± 11 vs 59 ± 12 years, P = .004) and had reduced resting ejection fractions (30 ± 9% vs 33 ± 7%, P = .02), CFVR of the LAD (1.96 ± 0.41 vs 2.23 ± 0.73, P = .001), and myocardial contractile reserve (variation in wall motion score index, -0.18 ± 0.17 vs -0.33 ± 0.28; P < .001). On multivariate logistic regression analysis, resting ejection fraction (hazard ratio [HR], 1.15; 95% CI, 1.03-1.29; P = .01), smoking habit (HR, 2.63; 95% CI, 1.23-5.62; P = .01), and LBBB (HR, 2.29; 95% CI, 1.05-5.04; P = .04) were independently associated with reduced CFVR, while restrictive transmitral pattern (HR, 2.56; 95% CI, 1.18-5.55; P = .02), end-diastolic volume (HR, 0.98; 95% CI, 0.67-0.99; P = .02), and LBBB (HR, 2.20; 95% CI, 1.11-4.34; P = .02) independently predicted reduced myocardial contractile reserve.

CONCLUSIONS

CFVR during vasodilator stress echocardiography is a suitable tool for assessing microvascular dysfunction in routine clinical practice. Patients with DCM and LBBB show more severe forms of microvascular dysfunction, which is related to worse left ventricular function and lack of contractile reserve. Therapeutic interventions to restore microvascular function may improve left ventricular function parameters in patients with DCM.

Evaluation of global longitudinal strain of left ventricle and regional longitudinal strain in the region of left ventricular leads predicts the response to cardiac resynchronization therapy in patients with ischemic heart failure

Myocardium viability in ischemic heart failure (HF) may affect the effect of cardiac resynchronization therapy (CRT). We hypothesized that longitudinal strain of 2D-STE, which reflects myocardium viability, can predict the response to CRT in patients with ischemic HF. 2D-STE was performed in 42 patients with HF, 1 week before and 1 year after CRT. GLS, RLS, and the LV synchrony index (SI), defined as the difference in timing to peak radial strain between LV anterior septal and posterior wall in LV short axis view, were calculated. A decrease in the LV end-systolic volume (LVESV) value of ≥ 15 % 1 year after CRT was defined as response to CRT. Twenty-nine patients responded to CRT (CRT-R group), while 13 patients did not respond and were assigned as CRT-NR group. Pre-CRT RLS and GLS were higher, while SI is lower, in CRT-R patients compared with CRT-NR group (p < 0.001). The ROC curve revealed that RLS of -11.5 % predicted response to CRT with sensitivity of 80.0 % and specificity of 77.9 % (AUC = 0.84, p < 0.001). Further, GLS of -13 % predicted response to CRT with sensitivity of 73.0 % and specificity of 73.4 % (AUC = 0.79, p < 0.001). In conclusion, LV dyssynchrony, GLS, and RLS calculated by 2D-STE can predict long-term response to CRT in patients with ischemic HF.

Is CRT pro-arrhythmic? A comparative analysis of the occurrence of ventricular arrhythmias between patients implanted with CRTs and ICDs

Aim and Hypothesis: Despite the proven symptomatic and mortality benefit of cardiac resynchronization therapy (CRT), there is anecdotal evidence it may be pro-arrhythmic in some patients. We aimed to identify if there were significant differences in the incidence of ventricular arrhythmias (VAs) in patients undergoing CRT-D and implantable cardioverter-defibrillators (ICD) implantation for primary prevention indication. We hypothesized that CRT is unlikely to be pro-arrhythmic based on the positive mortality and morbidity data from large randomized trials.

Methods and Results: A retrospective analysis of device therapies for VA in a primary prevention device cohort was performed. Patients with ischemic (IHD) and non-ischemic (DCM) cardiomyopathy and ICD or CRT+ICD devices (CRT-D) implanted between 2005 and 2007 without prior history of sustained VA were included for analysis. VA episodes were identified from stored electrograms and defined as sustained (VT/VF) if therapy [anti-tachycardia pacing (ATP) or shocks] was delivered or non-sustained (NSVT) if not. Of a total of 180 patients, 117 (68% male) were in the CRT-D group, 42% IHD, ejection fraction (EF) 24.5 ± 8.2% and mean follow-up 23.9 ± 9.8 months. 63 patients (84% male) were in the ICD group, 60% IHD, EF 27.7 ± 7.2% and mean follow-up 24.6 ± 10.8 months. Overall, there was no significant difference in the incidence of VA (35.0 vs. 38.1%, p = 0.74), sustained VT (21.3 vs. 28.5%, p = 0.36) or NSVT (12.8 vs. 9.5%, p = 0.63) and no significant difference in type of therapy received for VT/VF: ATP (68 vs. 66.6%, p = 0.73) and shocks (32 vs. 33.3%, p = 0.71) between the CRT-D and ICD groups, respectively.

Conclusion: In patients with cardiomyopathy receiving CRT-D and ICDs for primary prophylaxis, there was no significant difference in the incidence of VA. From this single center retrospective analysis, there is no evidence to support cardiac resynchronization causing pro-arrhythmia.

Prognostic value of left ventricular dyssynchrony by myocardial perfusion-gated SPECT in patients with normal and abnormal left ventricular functions

BACKGROUND

Left ventricular (LV) dyssynchrony by phase analysis has been studied by myocardial perfusion imaging (MPI)-gated SPECT in patients with LV dysfunction in various clinical settings. We aimed to investigate the routine use of phase analysis with gated SPECT for predicting cardiac outcome.

METHODS

Patients referred to a tertiary medical center in 2010-2011 prospectively underwent a gated SPECT and phase analysis, and follow-up for cardiac events. The values of clinical variables, MPI, LV function, and LV dyssynchrony in predicting cardiac events were tested by univariate and multivariate analyses.

RESULTS

The study group included 787 patients (66.5 ± 11 years, 81% men) followed for a mean duration of 18.3 ± 6.2 months. There were 45 (6%) cardiac events defined as composite endpoint; cardiac death occurred in 26 patients, and the rest had new-onset or worsening heart failure and life-threatening arrhythmias. In multivariate analysis, it was shown that NYHA class, diabetes mellitus, and LVEF <50% were the independent predictors for composite endpoint. However, the independent predictors for cardiac mortality were NYHA class (for each increment in class) and phase standard deviation (SD) (for each 10° increment).

CONCLUSION

Gated SPECT with phase analysis for the assessment of LV dyssynchrony can successfully predict cardiac death together with NYHA class, in patients with LV dysfunction.

Dynamic dyssynchrony and impaired contractile reserve of the left ventricle in beta-thalassaemia major: an exercise echocardiographic study

BACKGROUND

Performance of the left ventricle during exercise stress in thalassaemia patients is uncertain. We aimed to explore the phenomenon of dynamic dyssynchrony and assess contractile reserve in patients with beta-thalassaemia major and determine their relationships with myocardial iron load.

METHODS AND RESULTS

Thirty-two thalassaemia patients (16 males), aged 26.8 ± 6.9 years, without heart failure and 17 healthy controls were studied. Their left ventricular (LV) volumes, ejection fraction, systolic dyssynchrony index (SDI), and myocardial acceleration during isovolumic LV contraction (IVA) were determined at rest and during submaximal bicycle exercise testing using 3-dimensional and tissue Doppler echocardiography. Myocardial iron load as assessed by T2* cardiac magnetic resonance in patients were further related to indices of LV dyssynchrony and contractile reserve. At rest, patients had significantly greater LV SDI (p<0.001) but similar IVA (p = 0.22) compared with controls. With exercise stress, the prevalence of mechanical dyssynchrony (SDI>4.6%, control+2SD) increased from baseline 25% to 84% in patients. Δ SDI(exercise-baseline) correlated with exercise-baseline differences in LV ejection fraction (p<0.001) and stroke volume (p = 0.006). Compared with controls, patients had significantly less exercise-induced increase in LV ejection fraction, cardiac index, and IVA (interaction, all p<0.05) and had impaired contractile reserve as reflected by the gentler IVA-heart rate slope (p = 0.018). Cardiac T2* in patients correlated with baseline LV SDI (r = -0.44, p = 0.011) and IVA-heart rate slope (r = 0.36, p = 0.044).

CONCLUSIONS

Resting LV dyssynchrony is associated with myocardial iron load. Exercise stress further unveils LV dynamic dyssynchrony and impaired contractile reserve in patients with beta-thalassaemia major.

The performance of phase analysis of gated SPECT myocardial perfusion imaging in the presence of perfusion defects: a simulation study

BACKGROUND

Phase analysis has been developed and validated to measure left-ventricular dyssynchrony from gated SPECT myocardial perfusion imaging. The purpose of this study is to evaluate its performance in regions with perfusion defects.

METHODS

A special version of the eXtended CArdiac Torso digital phantom was developed to track B-spline points in each temporal frame. A region of 35 B-spline points in the inferior wall with normal and abnormal perfusion uptakes were simulated. Phase shifts were simulated in the same region, representing dyssynchronous contraction. Gated SPECT data were analyzed using a modified phase analysis algorithm, which tracked the same 35 B-spline points to calculate their phases.

RESULTS

Phases and phase shifts measured in the B-spline points with perfusion uptake in the range of 50%-10% did not significantly differ from those measured in the same B-spline points with normal perfusion uptake.

CONCLUSION

Phase analysis can accurately measure phases in regions with abnormal perfusion uptake as low as 10% of the perfusion uptake in the normal regions, which corresponded to a regional signal-to-noise ratio (SNR) of 12.0 or greater. In 42 consecutive patients with myocardial infarction >20% of the left ventricle, only two patients had a SNR within the perfusion defects below that threshold.

Relative merits of left ventricular dyssynchrony, left ventricular lead position, and myocardial scar to predict long-term survival of ischemic heart failure patients undergoing cardiac resynchronization therapy

BACKGROUND

The relative merits of left ventricular (LV) dyssynchrony, LV lead position, and myocardial scar to predict long-term outcome after cardiac resynchronization therapy remain unknown and were evaluated in the present study.

METHODS AND RESULTS

In 397 ischemic heart failure patients, 2-dimensional speckle tracking imaging was performed, with comprehensive assessment of LV radial dyssynchrony, identification of the segment with latest mechanical activation, and detection of myocardial scar in the segment where the LV lead was positioned. For LV dyssynchrony, a cutoff value of 130 milliseconds was used. Segments with <16.5% radial strain in the region of the LV pacing lead were considered to have extensive myocardial scar (>50% transmurality, validated in a subgroup with contrast-enhanced magnetic resonance imaging). The LV lead position was derived from chest x-ray. Long-term follow-up included all-cause mortality and hospitalizations for heart failure. Mean baseline LV radial dyssynchrony was 133±98 milliseconds. In 271 patients (68%), the LV lead was placed at the latest activated segment (concordant LV lead position), and the mean value of peak radial strain at the targeted segment was 18.9±12.6%. Larger LV radial dyssynchrony at baseline was an independent predictor of superior long-term survival (hazard ratio, 0.995; P=0.001), whereas a discordant LV lead position (hazard ratio, 2.086; P=0.001) and myocardial scar in the segment targeted by the LV lead (hazard ratio, 2.913; P<0.001) were independent predictors of worse outcome. Addition of these 3 parameters yielded incremental prognostic value over the combination of clinical parameters.

CONCLUSIONS

Baseline LV radial dyssynchrony, discordant LV lead position, and myocardial scar in the region of the LV pacing lead were independent determinants of long-term prognosis in ischemic heart failure patients treated with cardiac resynchronization therapy. Larger baseline LV dyssynchrony predicted superior long-term survival, whereas discordant LV lead position and myocardial scar predicted worse outcome.

Role of cardiac MRI and nuclear imaging in cardiac resynchronization therapy

Cardiac resynchronization has emerged as a highly effective therapy for heart failure. However, up to 40% of patients do not benefit from this treatment. In this Review, we discuss the potential role of MRI and nuclear molecular imaging in providing additional insights into the response to cardiac resynchronization therapy. Variables with potential prognostic and therapeutic values include the evaluation of cardiac dyssynchrony, scar, cardiac sympathetic function, myocardial blood flow, myocardial glucose and oxidative metabolism. Other molecular targets to characterize apoptosis, fatty acid metabolism, angiogenesis and angiotensin-converting enzyme activity will also be described. The potential use of these techniques in identifying and measuring responses to cardiac resynchronization therapy and future areas of research will be explored.

The variable functional effects of the pacing site in normal and scarred ventricles

BACKGROUND

The pacing site has been shown to influence functional improvement with cardiac resynchronization therapy. We evaluated the effects of the pacing site on left ventricular (LV) function in an animal model.

METHODS AND RESULTS

Equilibrium radionuclide angiography was acquired in sinus rhythm (NSR) and with ventricular pacing, from three pacing sites in seven normal and eight infarcted dogs. QRS duration, electrical activation pattern, wall motion, LV ejection fraction (EF), synchrony of ventricular contraction, and mean arterial pressure (MAP), were related to the pacing site and infarct size, during each of 120 episodes. Little changed during pacing in normals. In infarcted dogs, LV wall motion, and synchrony worsened, LVEF and MAP often fell. These changes related to altered activation patterns which were influenced by the pacing site but were not related to infarct size.

CONCLUSIONS

Hemodynamic and functional LV changes after infarction were found to vary with the pacing site and associated conduction and synchrony.

The utility of heart sounds and systolic intervals across the care continuum

Acoustic cardiography is an exciting, new, easy-to-use, modernized technology that incorporates already proven techniques of phonocardiography. Application of acoustic cardiography to clinical practice can improve diagnosis and management of heart failure patients. Its clinical use should help address some of the need for robust, inexpensive, and widely accessible technology for proactive heart failure diagnosis and management. Acoustic cardiographically recorded measurements have been correlated with both cardiac catheterization and echocardiographically determined hemodynamic parameters. Heart sounds captured by acoustic cardiograms have proven to assist clinicians in assessing dyspneic patients in the emergency department by utilizing the strong specificity of an S3 for detecting acute decompensated heart failure. Acoustic cardiography offers a cost-efficient, easy-to-use method to optimize the devices used in cardiac resyncronization therapy. The rapidly and easily obtainable information gathered by acoustic cardiography should foster its more widespread use in diagnosis and treatment of heart failure, including cardiac resyncronization therapy device optimization.

Left ventricular mechanical dyssynchrony as assessed by phase analysis of ECG-gated SPECT myocardial perfusion imaging

Cardiac resynchronization therapy (CRT) has shown benefits in patients with severe heart failure. The traditional criteria to select patients for CRT (NYHA class III or IV, depressed left ventricular (LV) ejection fraction, and prolonged QRS duration) result in at least 30% of the selected patients with no response to CRT. Recent studies with tissue Doppler imaging (TDI) have shown that the presence of LV dyssynchrony is an important predictor for response to CRT. Phase analysis has been developed to assess LV dyssynchrony from electrocardiography-gated single photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI). This technique uses Fourier harmonic functions to approximate regional wall thickening over the cardiac cycle and to calculate phases of regional onset of mechanical contraction (OMC). These OMC phases are obtained three-dimensionally over the left ventricle to generate an OMC phase distribution. Quantitative indices are calculated from the phase distribution to assess degree of LV dyssynchrony. This technique has been compared to other methods of measuring LV dyssynchrony and shown promising results in clinical evaluations. In this review, the phase analysis methodology is described and its up-to-date validations are summarized.

Temporal resolution of multiharmonic phase analysis of ECG-gated myocardial perfusion SPECT studies

BACKGROUND

Multiharmonic phase analysis (MHPA) was developed to assess left-ventricular dyssynchrony from gated myocardial perfusion single-photon emission computed tomography (GSPECT) studies. This study was intended to determine the temporal resolution of MHPA.

METHODS

A reference normal GSPECT study with 128 frames/cycle was simulated using NCAT, a nonuniform rational B-splines-based cardiac torso phantom. It was shifted in the time domain to insert phase delays. Realistic GSPECT studies (8 or 16 frames/cycle) were then obtained by down-sampling the reference and shifted studies. All GSPECT projections were generated with attenuation, scatter, collimator blurring, and Poisson noise. Seventeen regional phases were calculated from the GSPECT reconstructions (filtered back-projection without compensation for physical factors), using linear interpolation for the reference study, and MHPA for the realistic studies. Comparing the regional phases between the realistic studies without and with shifts determined whether MHPA could identify certain phase delays.

RESULTS

When there were enough counts/pixel (>10 counts/pixel), MHPA with either 1, 2, or 3 harmonics could resolve a phase difference of 5.6 degrees , corresponding to 1/64 of the cardiac cycle.

CONCLUSIONS

With clinically equivalent counts, the temporal resolution of MHPA is 1/64 of a cardiac cycle. Achieving this high temporal resolution from data with low temporal resolution demonstrates the benefit of replacing discrete points with continuous harmonic functions.

Assessment of left ventricular mechanical dyssynchrony by phase analysis of ECG-gated SPECT myocardial perfusion imaging

Cardiac resynchronization therapy (CRT) has shown benefits in patients with severe heart failure. However, at least 30% of patients selected for CRT by use of traditional criteria (New York Heart Association class III or IV, depressed left ventricular [LV] ejection fraction, and prolonged QRS duration) do not respond to CRT. Recent studies with tissue Doppler imaging have shown that the presence of LV dyssynchrony is an important predictor of response to CRT. Phase analysis has been developed to allow assessment of LV dyssynchrony by gated single photon emission computed tomography myocardial perfusion imaging. This technique uses Fourier harmonic functions to approximate regional wall thickness changes over the cardiac cycle and to calculate the regional onset-of-mechanical contraction phase. Once the onset-of-mechanical contraction phases are obtained 3-dimensionally over the left ventricle, a phase distribution map is formed that represents the degree of LV dyssynchrony. This technique has been compared with other methods of measuring LV dyssynchrony and shown promising results in clinical evaluations. In this review the phase analysis methodology is described, and its up-to-date validations are summarized.

Management of heart failure in elderly people

AIMS

To review currently available knowledge on presentation, clinical features and management of heart failure (HF) in elderly people.

METHODS

To review currently available evidence, we performed a thorough search of several evidence-based sources of information, including Cochrane Database of Systematic Reviews, Clinical Evidence, Evidence-based guidelines from National Guidelines Clearinghouse and a comprehensive MEDLINE search with the MeSH terms: 'heart failure', 'elderly' and 'management'.

RESULTS

A number of features of ageing may predispose elderly people to HF, and may impair the ability to respond to injuries. Another hallmark of elderly patients is the increasing prevalence of multiple coexisting chronic conditions and geriatric syndromes that may complicate the clinical presentation and evolution of HF. Although diagnosis may be challenging, because atypical symptoms and presentations are common, and comorbid conditions may mimic or complicate the clinical picture, diagnostic criteria do not change in elderly people. Drug treatment is not significantly different from that recommended in younger patients, and largely remains empiric, because clinical trials have generally excluded elderly people and patients with comorbid conditions. Disease management programmes may have the potential to reduce morbidity and mortality for patients with HF.

CONCLUSIONS

Heart failure is the commonest reason for hospitalisation and readmission among older adults. HF shows peculiar features in elderly people, and is usually complicated by comorbidities, presenting a significant financial burden worldwide, nevertheless elderly people have been generally excluded from clinical trials, and thus management largely remains empiric and based on evidence from younger age groups.