Left Ventricular Ejection Fraction for Sudden Death Risk Stratification and Guiding Implantable Cardioverter-defibrillators Implantation

Multimodality Imaging of Sudden Cardiac Death and Acute Complications in Acute Coronary Syndrome

Sudden cardiac death (SCD) is a potentially fatal event usually caused by a cardiac arrhythmia, which is often the result of coronary artery disease (CAD). Up to 80% of patients suffering from SCD have concomitant CAD. Arrhythmic complications may occur in patients with acute coronary syndrome (ACS) before admission, during revascularization procedures, and in hospital intensive care monitoring. In addition, about 20% of patients who survive cardiac arrest develop a transmural myocardial infarction (MI). Prevention of ACS can be evaluated in selected patients using cardiac computed tomography angiography (CCTA), while diagnosis can be depicted using electrocardiography (ECG), and complications can be evaluated with cardiac magnetic resonance (CMR) and echocardiography. CCTA can evaluate plaque, burden of disease, stenosis, and adverse plaque characteristics, in patients with chest pain. ECG and echocardiography are the first-line tests for ACS and are affordable and useful for diagnosis. CMR can evaluate function and the presence of complications after ACS, such as development of ventricular thrombus and presence of myocardial tissue characterization abnormalities that can be the substrate of ventricular arrhythmias.

Trends and outcomes of chronic coronary total occlusion-related ventricular tachyarrhythmias

Our study aims to establish trends and frequencies of ventricular tachyarrhythmia (VTA) among patients with chronic coronary total occlusion (CCTO). We identified CCTO hospitalizations with and without VTA using the National Inpatient Sample. A total of 911,579 CCTO-related hospitalizations were identified, with 92,450 (10.1%) encounters associated with VTA. The CCTO-VTA cohort showed higher all-cause mortality (adjusted odds ratio [aOR] = 4.45, P <  0.001), longer hospital stays (6.8 vs 4.6 days; P <  0.001), and higher hospital charges ($117,382 vs $75,419; P <  0.001) compared to the CCTO non-VTA group. Rates and odds of cardiogenic shock (aOR = 4.19), venous thromboembolism (aOR = 2.09), respiratory failure (aOR = 2.85), and requirement of mechanical ventilation (aOR = 4.23) were higher in the CCTO-VTA group (P <  0.001). Over time, there was an increase in VTA (9.2% in 2010 to 12.1% in 2014) and all-cause mortality (7.5% in 2010 to 12.4% in 2014; P <  0.001). Trends in VTA among patients with CCTO increased by 4.8% for undergoing percutaneous coronary intervention and by 2.5% for undergoing both percutaneous coronary intervention and coronary artery bypass grafting (P <  0.001). Occurrence of VTA among CCTO patients is associated with worse outcomes and higher resource utilization.

Prognostic Significance of CMR Findings in Patients with Known Coronary Artery Disease - Experience from a South Asian Country

Objectives:

South Asians (SA) have a higher burden of coronary artery disease (CAD) and are known to have a worse prognosis compared to other ethnicities. Therefore, it is imperative to improve the risk stratification of SA patient with CAD and to seek out newer prognostic markers beyond the conventional echocardiography.The aim of this study was to investigate whether variables obtained by cardiac magnetic resonance (CMR) improve risk stratification of South Asian patients with known CAD.

Material and Methods:

We retrospectively analyzed 147 patients with evidence of CAD that had a CMR at our center between January 2011 and January 2019. LV volumes and regional wall motions were acquired by cine images, while infarct size (IS) was measured by late gadolinium enhancement. At a mean follow-up of 3.36 ± 2.22 years, cardiac events (non-fatal myocardial infarction, hospitalization due to heart failure, life-threatening arrhythmia, or cardiac death) occurred in 49 patients. An IS ≥35%, left ventricular ejection fraction (LVEF) ≤31%, and a wall motion score index (WMSI) ≥1.9 were strongly associated with follow-up cardiac events (P < 0.001). Patients that had none or less than 3 of these factors, showed a lower risk of cardiac events (HR 0.22 CI [0.11–0.44] P < 0.001 and HR 0.12 CI [0.04–0.32] P < 0.001, respectively) compared to those with all three factors.

Conclusion:

Integration of CMR derived factors such as IS and WMSI with LVEF can improve the prognostication of the SA population with CAD. Better risk stratification of patients can lead to improved and cost-effective therapeutic strategies to ameliorate the prognosis of these patients.

Left ventricular midwall fibrosis as a predictor of sudden cardiac death in non-ischaemic dilated cardiomyopathy: a meta-analysis

Identification of patients with non‐ischaemic dilated cardiomyopathy (NICM) who are at risk of sudden cardiac death (SCD) and could benefit from an implantable cardioverter defibrillator (ICD) is challenging. The study aims to systematically assess the prognostic value of left ventricular (LV) midwall late gadolinium enhancement (LGE) pattern in patients with NICM and further explore its value on predicting SCD events. The study was prospectively registered in PROPSERO (CRD42019138468). We systematically searched PubMed, Ovid Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov to identify studies that evaluated the association between LV midwall LGE and clinical outcomes (all‐cause mortality, cardiovascular mortality, and SCD or aborted SCD endpoint) in NICM patients. A meta‐analysis was performed to determine pooled odds ratio (OR) for these adverse events. Seven studies including 1827 NICM patients over a mean follow‐up duration of 36.1 ± 19.3 months were included. The presence of LV midwall LGE pattern was observed in 562 (30.8%) patients. The pooled OR was 3.37 [95% confidence intervals (CIs): 1.35–8.42] for all‐cause mortality, 5.56 (95% CI: 1.23–25.22) for cardiovascular mortality, and 2.25 (95% CI: 1.16–3.16) for SCD or aborted SCD. In a subgroup analysis with mean ejection fraction cut‐off point of 35%, the pooled OR for SCD or aborted SCD was 2.06 (95% CI: 1.32–3.22) for LV ejection fraction (LVEF) > 35% and 2.49 (95% CI: 1.48–4.20) for LVEF ≤ 35%. In addition, our study indicated that LV midwall LGE showed an excellent negative predictive value in identifying high‐risk NICM patients and that the number needed to treat with ICD implantation in NICM patients with midwall LGE is 7. The presence of LV midwall on LGE is a significant prognosticator of adverse events in NICM patients. Additionally, patients with LV midwall LGE may be considered for ICD therapy irrespective of LVEF.

Left Ventricular Geometry and Replacement Fibrosis Detected by cMRI Are Associated with Major Adverse Cardiovascular Events in Nonischemic Dilated Cardiomyopathy

To investigate the relationship between left ventricular (LV) long-axis strain (LAS) and LV sphericity index (LVSI) and outcomes in patients with nonischemic dilated cardiomyopathy (NIDCM) and myocardial replacement fibrosis confirmed by late gadolinium enhancement (LGE) using cardiac magnetic resonance imaging (cMRI), we conducted a prospective study on 178 patients (48 ± 14.4 years; 25.2% women) with first NIDCM diagnosis. The evaluation protocol included ECG monitoring, echocardiography and cMRI. LAS and LVSI were cMRI-determined. Major adverse cardiovascular events (MACEs) were defined as a composite outcome including heart failure (HF), ventricular arrhythmias (VAs) and sudden cardiac death (SCD). After a median follow-up of 17 months, patients with LGE+ had increased risk of MACEs. Kaplan-Meier curves showed significantly higher rate of MACEs in patients with LGE+ (p < 0.001), increased LVSI (p < 0.01) and decreased LAS (p < 0.001). In Cox analysis, LAS (HR = 1.32, 95%CI (1.54–9.14), p = 0.001), LVSI [HR = 1.17, 95%CI (1.45–7.19), p < 0.01] and LGE+ (HR = 1.77, 95%CI (2.79–12.51), p < 0.0001) were independent predictors for MACEs. In a 4-point risk scoring system based on LV ejection fraction (LVEF) < 30%, LGE+, LAS > −7.8% and LVSI > 0.48%, patients with 3 and 4 points had a significantly higher risk for MACEs. LAS and LVSI are independent predictors of MACEs and provide incremental value beyond LVEF and LGE+ in patients with NIDCM and myocardial fibrosis.

The risk and prevention of sudden death in patients with heart failure with reduced ejection fraction

PURPOSE OF REVIEW

Patients with heart failure are at increased risk of sudden cardiac death. The methods to predict patients at high risk of sudden cardiac death in heart failure are neither sensitive nor specific; both overestimating risk in those with ejection fractions less than 35% and not identifying those at risk with ejection fractions greater than 35%.

RECENT FINDINGS

The absolute risk of sudden cardiac death in patients with heart failure have decreased over the past 20 years. New novel tools are being developed and tested to identify those at higher risk of sudden cardiac death. Reduction in the risk of sudden cardiac death has been achieved with the use of beta-blockers, spironolactone, sacubitril-valsartan, cardiac resynchronization and implantable cardioverter defibrillators.

SUMMARY

The use of contemporary treatments for patients with heart failure can reduce the risk of sudden cardiac death, but research is required to identify those at highest risk.

Cardiac Magnetic Resonance Left Ventricular Mechanical Uniformity Alterations for Risk Assessment After Acute Myocardial Infarction

Background Despite limitations as a stand-alone parameter, left ventricular (LV) ejection fraction is the preferred measure of myocardial function and marker for postinfarction risk stratification. LV myocardial uniformity alterations may provide superior prognostic information after acute myocardial infarction, which was the subject of this study. Methods and Results Consecutive patients with acute myocardial infarction (n=1082; median age: 63 years; 75% male) undergoing cardiac magnetic resonance at a median of 3 days after infarction were included in this multicenter observational study. Circumferential and radial uniformity ratio estimates were derived from cardiac magnetic resonance feature tracking as markers of mechanical uniformity alterations (values between 0 and 1 with 1 reflecting perfect uniformity). The clinical end point was the 12-month rate of major adverse cardiac events, consisting of all-cause death, reinfarction, and new congestive heart failure. Patients with major adverse cardiac events (n=73) had significantly impaired circumferential uniformity ratio estimates (0.76 [interquartile range: 0.67-0.86] versus 0.84 [interquartile range: 0.76-0.89]; P<0.001) and radial uniformity ratio estimates (0.69 [interquartile range: 0.60-0.79] versus 0.76 [interquartile range: 0.67-0.83]; P<0.001) compared with patients without events. Although uniformity estimates did not provide independent prognostic information in the overall cohort, a circumferential uniformity ratio estimate below the median of 0.84 emerged as an independent predictor of outcome in postinfarction patients with LV ejection fraction >35% (n=959), even after adjustment for established risk factors (hazard ratio: 1.99; 95% CI, 1.06-3.74; P=0.033 in multivariable Cox regression analysis). In contrast, LV ejection fraction was not associated with adverse events in this subgroup of patients with acute myocardial infarction. Conclusions Cardiac magnetic resonance-derived estimates of mechanical uniformity alterations are novel markers for risk assessment after acute myocardial infarction, and the circumferential uniformity ratio estimate provides independent prognostic information for patients with preserved or only moderately reduced LV ejection fraction.

Impact of Coronary Artery Chronic Total Occlusion on Arrhythmic and Mortality Outcomes: A Systematic Review and Meta-Analysis

OBJECTIVES

This study aimed to examine the relationship between chronic coronary artery total occlusion (CTO) status and the occurrence of ventricular tachycardia (VT)/ventricular fibrillation (VF) or appropriate implantable cardioverter-defibrillator (ICD) therapy.

BACKGROUND

CTO is a significant problem in patients with ischemic heart disease. However, the extent to which it predisposes affected individuals to VT/VF and whether these arrhythmic events could be prevented by revascularization are unclear. Therefore, a systematic review and meta-analysis were conducted to examine the relationship between CTO status and the occurrence of VT/VF or appropriate ICD therapy.

METHODS

PubMed and Embase databases were searched until November 16, 2017, identifying 137 studies.

RESULTS

Seventeen studies involving 54,594 subjects (mean age, 61 ± 21 years of age, 81% male) with a mean follow-up of 43 ± 31 months were included. The presence of CTO was associated with higher risk of VT/VF or appropriate ICD therapy (adjusted hazard ratio [aHR]: 1.99; 95% confidence interval (CI): 1.53 to 2.59; p < 0.0001, I² = 3%) but not in cardiac mortality (aHR: 2.59; 95% CI: 0.64 to 10.59; p = 0.18, I² = 86%) or in all-cause mortality (aHR: 1.70; 95% CI: 0.84 to 3.46; p = 0.14; I² = 64%). Compared to patients with non-infarct-related CTOs, those with infarct-related CTOs have a higher risk of VT/VF or appropriate ICD therapy (aHR: 2.47; 95% CI: 1.76 to 3.46; p < 0.0001; I² = 14%), cardiac mortality (aHR: 2.73; 95% CI: 1.02 to 7.30; p < 0.05; I² = 79%) and higher all-cause mortality (aHR: 1.69; 95% CI: 1.19 to 2.40; p < 0.01; I² = 40%). Nonrevascularization of CTOs tended to be associated with an increased risk of all-cause mortality compared to successful revascularization (unadjusted HR: 1.52; 95% CI: 0.96 to 2.43; p = 0.08; I² = 76).

CONCLUSIONS

CTOs, especially infarct-related, are associated with high risk of VT/VF or appropriate ICD therapy and mortality. ICD implantation could be beneficial. However, it is not clear that revascularization has an impact on the outcome of patients with CTOs.

Role of Cardiac Imaging in Evaluating Risk for Sudden Cardiac Death

Sudden cardiac death (SCD) is a major cause of death from cardiovascular disease. Our ability to predict patients at the highest risk of developing lethal ventricular arrhythmias remains limited. Despite recent studies evaluating risk stratification tools, there is no optimal strategy. Cardiac imaging provides the opportunity to assess left ventricular ejection fraction, strain, fibrosis, and sympathetic innervation, all of which are pathophysiologically related to SCD risk. These modalities may play a role in the identification of vulnerable anatomic substrates that provide the pathophysiologic basis for SCD. Further studies are required to identify optimal imaging platform for risk assessment.

Risk stratification in patients with heart failure: the value of considering both global longitudinal left ventricular strain and mechanical dispersion

In previous studies, mechanical dispersion (MD) predicted ventricular arrhythmias independently of left ventricular ejection fraction (LVEF). Moreover, the combination of MD and global longitudinal strain (GLS) increased the prediction of arrhythmic events. We investigated the prognostic value of a new 2-dimensional strain index, GLS/MD, in patients with heart failure (HF). We analyzed 340 consecutive HF outpatients in sinus rhythm. Echocardiography was performed at 1.6 ± 0.4 months after hospital discharge. The end point included sudden cardiac death, ventricular fibrillation, and sustained ventricular tachycardia (SCD/VA). During the follow-up period (36 ± 9 months), SCD/VA occurred in 48 patients (14.1%). A multivariate Cox regression analysis, which included LVEF, early diastolic transmitral / mitral annular velocity ratio (E/E'), GLS, MD, and GLS/MD in the model, revealed that GLS/MD was the best independent predictor of SCD/VA (HR = 3.22, 95% confidence interval = 1.72-6.15, p = 0.03). Separate inclusion of LVEF, systolic mitral annular velocity, E/E', GLS, and MD together with GLS/MD showed that GLS/MD remained the best predictor of SCD/VA (each p < 0.05). The optimal GLS/MD cutoff value to predict SCA/VA was -0.20%/ms (80% sensitivity, 76% specificity). Irrespective of LVEF, free survival was significantly better in patients with GLS/MD ≤ -0.2%/ms (log-rank test, p < 0.001). In conclusion, GLS/MD may improve cardiovascular risk stratification in subjects with HF.

Late Gadolinium Enhancement and the Risk for Ventricular Arrhythmias or Sudden Death in Dilated Cardiomyopathy: Systematic Review and Meta-Analysis

OBJECTIVES

The aim of this study was to evaluate the association between late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging and ventricular arrhythmias or sudden cardiac death (SCD) in patients with dilated cardiomyopathy (DCM).

BACKGROUND

Risk stratification for SCD in DCM needs to be improved.

METHODS

A systematic review and meta-analysis were conducted. A systematic search of PubMed and Ovid was performed, and observational studies that analyzed the arrhythmic endpoint (sustained ventricular arrhythmia, appropriate implantable cardioverter-defibrillator [ICD] therapy, or SCD) in patients with DCM, stratified by the presence or absence of LGE, were included.

RESULTS

Twenty-nine studies were included, accounting for 2,948 patients. The studies covered a wide spectrum of DCM, with a mean left ventricular ejection fraction between 20% and 43%. LGE was significantly associated with the arrhythmic endpoint both in the overall population (odds ratio: 4.3; p < 0.001) and when including only those studies that performed multivariate analysis (hazard ratio: 6.7; p < 0.001). The association between LGE and the arrhythmic endpoint remained significant among studies with mean left ventricular ejection fractions >35% (odds ratio: 5.2; p < 0.001) and was maximal in studies that included only patients with primary prevention ICDs (odds ratio: 7.8; p = 0.008).

CONCLUSIONS

Across a wide spectrum of patients with DCM, LGE is strongly and independently associated with ventricular arrhythmia or SCD. LGE could be a powerful tool to improve risk stratification for SCD in patients with DCM. These results raise 2 major questions to be addressed in future studies: whether patients with LGE could benefit from primary prevention ICDs irrespective of their left ventricular ejection fractions, while patients without LGE might not need preventive ICDs despite having severe left ventricular dysfunction.

Canadian Cardiovascular Society/Canadian Heart Rhythm Society 2016 Implantable Cardioverter-Defibrillator Guidelines

Sudden cardiac death is a major public health issue in Canada. However, despite the overwhelming evidence to support the use of implantable cardioverter defibrillators (ICDs) in the prevention of cardiac death there remains significant variability in implantation rates across Canada. Since the most recent Canadian Cardiovascular Society position statement on ICD use in Canada in 2005, there has been a plethora of new scientific information to assist physicians in their discussions with patients considered for ICD implantation to prevent sudden cardiac death due to ventricular arrhythmias. We have reviewed, critically appraised, and synthesized the pertinent evidence to develop recommendations regarding: (1) ICD implantation in the primary and secondary prevention of sudden cardiac death in patients with and without ischemic heart disease; (2) when it is reasonable to withhold ICD implantation on the basis of comorbidities; (3) ICD implantation in patients listed for heart transplantation; (4) implantation of a single- vs dual-chamber ICD; (5) implantation of single- vs dual-coil ICD leads; (6) the role of subcutaneous ICDs; and (7) ICD implantation infection prevention strategies. We expect that this document, in combination with the companion article that addresses the implementation of these guidelines, will assist all medical professionals with the care of patients who have had or at risk of sudden cardiac death.

The implantable cardioverter defibrillator in primary prevention: a revision of monocentric study group

AIMS

To evaluate the outcome of a population implanted with an implantable cardioverter defibrillator (ICD) for primary prevention in terms of mortality, morbidity and appropriate and inappropriate interventions. Secondly, to compare the performances of single-chamber vs. dual-chamber devices.

METHODS

We examined all patients with CAD or CMD who received an ICD in primary prevention with at least 6 months of follow-up. For each patient were evaluated, primarily, survival, complications related to the implantation and performance of the device (antitachycardia pacing/shock).

RESULTS

Of 193 patients, 163 were men (84.5). Mean age was 64.4 ± 10 years. One hundred and twenty patients (62%) were affected by CAD and 73 (38%) by CMD. The ejection fraction was 26 ± 6%. Fifty-three patients (27.5%) received a dual-chamber ICD, whereas 140 (72.5%) received a single-chamber ICD. There were periprocedural complications in 5.2% of the patients. At a mean follow-up of 49.9 months, 55 patients (28.5%) died. Appropriate interventions were documented in 40 patients (20.7%). In 36 patients (18%), inappropriate interventions occurred. Patients implanted with dual-chamber ICD had an overall mortality of 17% compared to 32.4% for those implanted with single-chamber ICD (P = 0.029). Mortality was higher in patients with CAD (33.9%) (P = 0.032). Among the fatalities, 69% occurred in patients who had an ejection fraction 25% or less at the time of implantation and 31% in patients with an ejection fraction greater than 25% (P = 0.013).

CONCLUSIONS

The 4-year survival was 72%. The overall mortality was higher in patients with CAD. More than two-thirds of the deceased had an ejection fraction less than 25%. The dual-chamber ICD patients had a significantly lower mortality rate.

Enhanced risk profiling of implanted defibrillator shocks with circulating SCN5A mRNA splicing variants: a pilot trial

OBJECTIVES

The aim of this study was to determine the association of SCN5A cardiac sodium (Na(+)) channel mRNA splice variants in white blood cells (WBCs) with risk of arrhythmias in heart failure (HF).

BACKGROUND

HF is associated with upregulation of two cardiac SCN5A mRNA splice variants that encode prematurely truncated, nonfunctional Na(+) channels. Because circulating WBCs demonstrate similar SCN5A splicing patterns, we hypothesized that these WBC-derived splice variants might further stratify patients with HF who are at risk for arrhythmias.

METHODS

Simultaneously obtained myocardial core samples and WBCs were compared for SCN5A variants C (VC) and D (VD). Circulating variant levels were compared among patients with HF, divided into three groups: HF without an implantable cardioverter-defibrillator (ICD), HF with an ICD without appropriate intervention, and HF with an ICD with appropriate intervention.

RESULTS

Myocardial tissue-derived SCN5A variant expression levels strongly correlated with circulating WBC samples for both VC and VD variants (r = 0.78 and 0.75, respectively). After controlling for covariates, patients with HF who had received an appropriate ICD intervention had higher expression levels of both WBC-derived SCN5A variants compared with patients with HF with ICDs who had not received appropriate ICD intervention (odds ratio, 3.25; 95% CI, 1.64-6.45; p = 0.001). Receiver operating characteristic analysis revealed that circulating SCN5A variant levels were highly associated with the risk for appropriate ICD intervention (area under the curve ≥0.97).

CONCLUSIONS

Circulating expression levels of SCN5A variants were strongly associated with myocardial tissue levels. Furthermore, circulating variant levels were correlative with arrhythmic risk as measured by ICD events in an HF population within 1 year. (Sodium Channel Splicing in Heart Failure Trial [SOCS-HEFT]; NCT01185587).

Mouse models of arrhythmogenic cardiovascular disease: challenges and opportunities

Arrhythmogenic cardiovascular disease is associated with significant morbidity and mortality and, in spite of therapeutic advances, remains an enormous public health burden. The scope of this problem motivates efforts to delineate the molecular, cellular and systemic mechanisms underlying increased arrhythmia risk in inherited and acquired cardiac and systemic disease. The mouse is used increasingly in these efforts owing to the ease with which genetic strategies can be exploited and mechanisms can be probed. The question then arises whether the mouse has proven to be a useful model system to delineate arrhythmogenic cardiovascular disease mechanisms. Rather than trying to provide a definite answer, the goal here is to consider the issues that arise when using mouse models and to highlight the opportunities.

A combined anatomic and electrophysiologic substrate based approach for sudden cardiac death risk stratification

BACKGROUND

Although left ventricular ejection fraction (LVEF) is the primary determinant for sudden cardiac death (SCD) risk stratification, in isolation, LVEF is a sub-optimal risk stratifier. We assessed whether a multi-marker strategy would provide more robust SCD risk stratification than LVEF alone.

METHODS

We collected patient-level data (n = 3355) from 6 studies assessing the prognostic utility of microvolt T-wave alternans (MTWA) testing. Two thirds of the group was used for derivation (n = 2242) and one-third for validation (n = 1113). The discriminative capacity of the multivariable model was assessed using the area under the receiver-operating characteristic curve (c-index). The primary endpoint was SCD at 24 months.

RESULTS

In the derivation cohort, 59 patients experienced SCD by 24 months. Stepwise selection suggested that a model based on 3 parameters (LVEF, coronary artery disease and MTWA status) provided optimal SCD risk prediction. In the derivation cohort, the c-index of the model was 0.817, which was significantly better than LVEF used as a single variable (0.637, P < .001). In the validation cohort, 36 patients experienced SCD by 24 months. The c-index of the model for predicting the primary endpoint was again significantly better than LVEF alone (0.774 vs 0.671, P = .020).

CONCLUSIONS

A multivariable model based on presence of coronary artery disease, LVEF and MTWA status provides significantly more robust SCD risk prediction than LVEF as a single risk marker. These findings suggest that multi-marker strategies based on different aspects of the electro-anatomic substrate may be capable of improving primary prevention implantable cardioverter-defibrillator treatment algorithms.

Late gadolinium enhancement cardiac magnetic resonance imaging for the prediction of ventricular tachyarrhythmic events: a meta-analysis

AIMS

Approaches to the risk stratification for sudden cardiac death (SCD) remain unsatisfactory. Although late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR) for SCD risk stratification has been evaluated in several studies, small sample size has limited their clinical validity. We performed this meta-analysis to better gauge the predictive accuracy of LGE-CMR for SCD risk stratification.

METHODS AND RESULTS

Electronic databases and published bibliographies were systematically searched to identify studies evaluating the association between the extent of LV scar on LGE-CMR and ventricular arrhythmic events [SCD, resuscitated cardiac arrest, the occurrence of ventricular arrhythmias, or appropriate implantable cardioverter defibrillator (ICD) therapy]. Only studies enrolling patients with CAD or non-ischaemic cardiomyopathy were included. Summary estimates of the relative risk (RR) and likelihood ratios (LRs) were calculated using random effects models. Eleven studies comprising 1105 patients were identified. During a mean/median follow-up of 8.5-41 months 207 patients had ventricular arrhythmic events. Ventricular arrhythmic events were more common in patients with a greater extent of LV scar: RR 4.33 [95% confidence interval (CI) 2.98-6.29], positive LR 1.98 (95% CI 1.66-2.37), and negative LR 0.33 (95% CI 0.24-0.46).

CONCLUSION

The extent of LGE on CMR is strongly associated with the occurrence of ventricular arrhythmias in patients with reduced LVEF and may be a valuable risk stratification tool for identifying patients who will benefit from ICD therapy. However, uncertainties regarding clinical application persist and need to be addressed prior to introduction into broad clinical practice.

Model-based evaluation and optimization of cardiac monitoring protocols for adjuvant treatment of breast cancer with trastuzumab

PURPOSE

Trastuzumab treatment is associated with occurrence of cardiac toxicity, for which monitoring of the left ventricular ejection fraction (LVEF) is indicated. The performance of the currently used monitoring protocol as defined in the summary of product characteristics (SPC) is however unknown. The objective of this analysis was to develop a model-based framework for evaluation and optimization of cardiac monitoring strategies.

METHODS

The model-based framework comprised a previously developed exposure-response model for trastuzumab induced changes in LVEF, and a protocol-execution model that allowed incorporation of treatment interventions as described by a monitoring protocol. Metrics for evaluation of toxicity, dose intensity and monitoring burden were defined to allow evaluation and optimization of cardiac monitoring protocols.

RESULTS

The success of a protocol-defined dose reduction was improved from 40% for the SPC-based protocol, to 79% for a scoring-based protocol, thereby decreasing the observed severity of cardiotoxicity. Including adaptation based on risk-profile allowed reduction of the mean number of LVEF measurements by 19%.

CONCLUSIONS

This model-based evaluation approach enabled evaluation and optimization of cardiac monitoring protocols that would be difficult to evaluate in a clinical setting. This approach can potentially be applied for other drugs that use repeated evaluation of continuous biomarkers for toxicity.

Implantable cardioverter defibrillator therapy activation for high risk patients with relatively well preserved left ventricular ejection fraction. Does it really work?

BACKGROUND

Current guidelines for the primary prevention of sudden cardiac death have used a left ventricular ejection fraction (LVEF) ≤ 35% as a critical point to justify implantable cardioverter defibrillator (ICD) implantation in post myocardial infarction patients and in those with nonischemic dilated cardiomyopathy. We compared mortality and ICD activation rates among different ICD group recipients using a cut-off value for LVEF ≤ 35%.

METHODS

We followed up for a mean period of 41.1 months 495 ICD recipients (442 males, 65.6 years old, 68.9% post myocardial infarction patients, 422 with LVEF ≤ 35%). Prevention was considered primary in patients who fulfilled guidelines criteria or had inducible ventricular arrhythmia during programmed ventricular stimulation for patients with LVEF >35%.

RESULTS

Over the course of the trial, 84 of 495 patients died; 69 experienced cardiac death (6 sudden) and 15 non cardiac death. ICD recipients with LVEF ≤ 35% compared to those with preserved LVEF (mean LVEF=43%) had a greater incidence of total mortality (18% vs. 11%, log rank p=0.028) and cardiac death (15.4% vs. 5.5%, log rank p=0.005). There was no difference in the incidence for appropriate device therapy between patients with LVEF ≤ 35% and those with LVEF >35% (56.9% vs. 65.8%, log rank p=0.93). In the multivariate analysis the presence of advanced New York Heart Association stage predicted both total mortality (HR=2.69, 95% CI 1.771-4.086) and cardiac death (HR=3.437, 95% CI 2.163-5.463).

CONCLUSIONS

ICD therapy may protect heart failure patients at early stages from arrhythmic morbidity and mortality, based on an electrophysiology-guided risk stratification approach.

Do patients at high risk of nonsudden cardiac death benefit from prophylactic ICD therapy?

PURPOSE OF REVIEW

Randomized controlled trials have established that prophylactic implantable cardioverter defibrillator (ICD) therapy improves survival in patients with reduced left ventricular ejection fraction (LVEF). However, mortality reduction is not uniform across the implanted population and recent data have highlighted the importance of nonsudden cardiac death (non-SCD) risk in predicting benefit from ICD therapy. This review explores the importance of non-SCD risk in patient selection for prophylactic ICD therapy, as well as the proposed approaches to identify potential ICD recipients at high risk of non-SCD.

RECENT FINDINGS

Data from randomized controlled trials have demonstrated that patients at high risk of non-SCD do not gain significant survival benefit from prophylactic ICD therapy irrespective of their risk of SCD. A variety of strategies to identify low LVEF patients at high risk of non-SCD have been proposed. These include the use of individual risk markers, such as advanced age and renal dysfunction, the presence of cardiac and noncardiac comorbidities, and the use of more complex risk scores.

SUMMARY

Non-SCD risk is an important issue in patient selection for prophylactic ICD therapy. However, the optimal strategy to identify patients at high non-SCD risk is unclear and further research is needed.