Infarct tissue heterogeneity assessed with contrast-enhanced MRI predicts spontaneous ventricular arrhythmia in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillator

Clinical benefit of cardiac resynchronization therapy with a defibrillator in patients with an ejection fraction > 35% estimated by cardiac magnetic resonance

INTRODUCTION AND OBJECTIVES

Cardiac resynchronization therapy with a defibrillator prolongs survival and improves quality of life in advanced heart failure. Traditionally, patients with ejection fraction > 35 estimated by echocardiography have been excluded. We assessed the prognostic impact of this therapy in a group of patients with severely depressed systolic function as assessed by echocardiography but with an ejection fraction > 35% as assessed by cardiac magnetic resonance.

METHODS

We analyzed consecutive patients admitted for decompensated heart failure between 2004 and 2011. The patients were in functional class II-IV, with a QRS ≥ to 120 ms, ejection fraction ≤ 35% estimated by echocardiography, and a cardiac magnetic resonance study. We included all patients (n=103) who underwent device implantation for primary prevention. Ventricular arrhythmia, all-cause mortality and readmission for heart failure were considered major cardiac events. The patients were divided into 2 groups according to systolic function assessed by magnetic resonance.

RESULTS

The 2 groups showed similar improvements in functional class and ejection fraction at 6 months. We found a nonsignificant trend toward a higher risk of all-cause mortality in patients with systolic function ≤ 35% at long-term follow-up. The presence of a pattern of necrosis identified patients with a worse prognosis for ventricular arrhythmias and mortality in both groups.

CONCLUSIONS

We conclude that cardiac resynchronization therapy with a defibrillator leads to a similar clinical benefit in patients with an ejection fraction ≤ 35% or > 35% estimated by cardiac magnetic resonance. Analysis of the pattern of late gadolinium enhancement provides additional information on arrhythmic risk and long-term prognosis.

Assessment of ventricular tachycardia scar substrate by intracardiac echocardiography

BACKGROUND

Intracardiac echocardiography (ICE) is increasingly used to guide complex ablation procedures. This study aimed to assess the scar substrate of ventricular tachycardia (VT) by ICE in patients undergoing VT ablation.

METHODS

In 22 patients undergoing VT ablation (10 ischemic, 12 nonischemic), the Biosense CARTOSOUND module (Biosense Webster, Diamond Bar, CA, USA) was used for three-dimensional reconstruction of the ventricles. The characteristics and appearance with ICE imaging of voltage-defined scar zones (bipolar voltage <0.5 mV), border zones (0.5-1.5 mV), and normal myocardium (>1.5 mV) on electroanatomic maps were evaluated. The standard image analysis software Image J (National Institutes of Health, Bethesda, MD, USA) was used to analyze signal intensity (mean pixel signal intensity unit [SIU]) and heterogeneity (standard deviation of signal intensity in analyzed area) on ICE images.

RESULTS

A total of 83 myocardial areas were analyzed from two-dimensional ICE images (15 scars, 31 border zones, and 37 normal). Voltage-defined scar zones had increased signal intensities compared to border zones (149 SIU vs 104 SIU, P < 0.0001) and normal myocardium (88 SIU, P < 0.0001). Border zones were more likely to have heterogeneous densities compared to normal myocardium (standard deviation of signal intensity 20 SIU vs 12 SIU, P < 0.0001). In receiver-operator characteristic analyses, signal intensity ≥ 137 SIU differentiated scar from nonscar zones (area under curve 0.91, P < 0.0001). Software-based color enhancement of areas with signal intensity ≥ 137 SIU allowed identification of the VT substrate in all 15 patients with voltage-defined scar zones.

CONCLUSIONS

ICE provides important information about the VT anatomical substrate and may have potential to identify areas of scarred myocardium.

Catheter ablation of ventricular arrhythmias: targets, tactics, and tools

PURPOSE OF REVIEW

Drug-refractory ventricular tachycardia in the setting of structural heart disease results in frequent implantable cardioverter defibrillator therapies and an increased risk of heart failure. Management requires catheter ablation procedures for effective suppression of the arrhythmia.

RECENT FINDINGS

Imaging and electroanatomic mapping technologies provide new insights into the myocardial structural abnormalities responsible for ventricular tachycardia. Integration of imaging data with three-dimensional mapping systems coupled with improved targeting of abnormal electrical signals may improve the ablation outcomes. New ablation tools show promise for the effective ablation of previously unreachable myocardial ventricular tachycardia circuits.

SUMMARY

Catheter ablation procedures have evolved over the last 2 decades. Improved technology may contribute to more widespread utilization of catheter ablation in the future.

Screening entire health system ECG databases to identify patients at increased risk of death

BACKGROUND

Current methods to identify patients at higher risk for sudden cardiac death, primarily left ventricular ejection fraction ≤35%, miss ≈80% of patients who die suddenly. We tested the hypothesis that patients with elevated QRS-scores (index of myocardial scar) and wide QRS-T angles (index abnormal depolarization-repolarization relationship) have high 1-year all-cause mortality and could be further risk stratified with clinical characteristics.

METHODS AND RESULTS

We screened all 12-lead ECGs over 6 months at 2 large hospital systems and analyzed clinical characteristics and 1-year mortality. Patients with ECGs obtained in hospital areas with known high mortality rates were excluded. At the first hospital, QRS-score ≥5 and QRS-T angle ≥105° identified 8.0% of patients and was associated with an odds ratio of 2.79 (95% confidence interval, 2.10-3.69) for 1-year mortality compared with patients below both ECG thresholds (13.9% versus 5.5% death rate). Left ventricular ejection fraction was >35% in 82% of the former group of patients, and addition of ECG measures to left ventricular ejection fraction increased the discrimination of death risk (P<0.0001). At the second hospital, the odds ratio was 2.42 (1.95-3.01) for 1-year mortality (8.8% versus 3.8%). Adjustment for patient characteristics eliminated interhospital differences. Multivariable adjusted odds ratio combining data from both hospitals was 1.53 (1.28-1.83). Increasing heart rate and chronic renal impairment further predicted mortality.

CONCLUSIONS

Screening hospital ECG databases with QRS-scoring and QRS-T angle analysis identifies patients with high 1-year all-cause mortality and predominantly preserved left ventricular ejection fraction. This approach may represent a widely available method to identify patients at increased risk of death.

Regional myocardial sympathetic denervation predicts the risk of sudden cardiac arrest in ischemic cardiomyopathy

OBJECTIVES

The PAREPET (Prediction of ARrhythmic Events with Positron Emission Tomography) study sought to test the hypothesis that quantifying inhomogeneity in myocardial sympathetic innervation could identify patients at highest risk for sudden cardiac arrest (SCA).

BACKGROUND

Left ventricular ejection fraction (LVEF) is the only parameter identifying patients at risk of SCA who benefit from an implantable cardiac defibrillator (ICD).

METHODS

We prospectively enrolled 204 subjects with ischemic cardiomyopathy (LVEF ≤35%) eligible for primary prevention ICDs. Positron emission tomography (PET) was used to quantify myocardial sympathetic denervation ((11)C-meta-hydroxyephedrine [(11)C-HED]), perfusion ((13)N-ammonia) and viability (insulin-stimulated (18)F-2-deoxyglucose). The primary endpoint was SCA defined as arrhythmic death or ICD discharge for ventricular fibrillation or ventricular tachycardia >240 beats/min.

RESULTS

After 4.1 years follow-up, cause-specific SCA was 16.2%. Infarct volume (22 ± 7% vs. 19 ± 9% of left ventricle [LV]) and LVEF (24 ± 8% vs. 28 ± 9%) were not predictors of SCA. In contrast, patients developing SCA had greater amounts of sympathetic denervation (33 ± 10% vs. 26 ± 11% of LV; p = 0.001) reflecting viable, denervated myocardium. The lower tertiles of sympathetic denervation had SCA rates of 1.2%/year and 2.2%/year, whereas the highest tertile had a rate of 6.7%/year. Multivariate predictors of SCA were PET sympathetic denervation, left ventricular end-diastolic volume index, creatinine, and no angiotensin inhibition. With optimized cut-points, the absence of all 4 risk factors identified low risk (44% of cohort; SCA <1%/year); whereas ≥2 factors identified high risk (20% of cohort; SCA ∼12%/year).

CONCLUSIONS

In ischemic cardiomyopathy, sympathetic denervation assessed using (11)C-HED PET predicts cause-specific mortality from SCA independently of LVEF and infarct volume. This may provide an improved approach for the identification of patients most likely to benefit from an ICD. (Prediction of ARrhythmic Events With Positron Emission Tomography [PAREPET]; NCT01400334).

Probability mapping of scarred myocardium using texture and intensity features in CMR images

Background

The myocardium exhibits heterogeneous nature due to scarring after Myocardial Infarction (MI). In Cardiac Magnetic Resonance (CMR) imaging, Late Gadolinium (LG) contrast agent enhances the intensity of scarred area in the myocardium.

Methods

In this paper, we propose a probability mapping technique using Texture and Intensity features to describe heterogeneous nature of the scarred myocardium in Cardiac Magnetic Resonance (CMR) images after Myocardial Infarction (MI). Scarred tissue and non-scarred tissue are represented with high and low probabilities, respectively. Intermediate values possibly indicate areas where the scarred and healthy tissues are interwoven. The probability map of scarred myocardium is calculated by using a probability function based on Bayes rule. Any set of features can be used in the probability function.

Results

In the present study, we demonstrate the use of two different types of features. One is based on the mean intensity of pixel and the other on underlying texture information of the scarred and non-scarred myocardium. Examples of probability maps computed using the mean intensity of pixel and the underlying texture information are presented. We hypothesize that the probability mapping of myocardium offers alternate visualization, possibly showing the details with physiological significance difficult to detect visually in the original CMR image.

Conclusion

The probability mapping obtained from the two features provides a way to define different cardiac segments which offer a way to identify areas in the myocardium of diagnostic importance (like core and border areas in scarred myocardium).

Value of early cardiovascular magnetic resonance for the prediction of adverse arrhythmic cardiac events after a first noncomplicated ST-segment-elevation myocardial infarction

BACKGROUND

Infarct size (IS) determined by cardiac magnetic resonance (CMR) has proven an additional value, on top of left ventricular ejection fraction (LVEF), in prediction of adverse arrhythmic cardiac events (AACEs) in chronic ischemic heart disease. Its value soon after an acute ST-segment-elevation myocardial infarction remains unknown. Our aim was to determine whether early CMR can improve AACE risk prediction after acute ST-segment-elevation myocardial infarction.

METHODS AND RESULTS

Patients admitted for a first noncomplicated ST-segment-elevation myocardial infarction were prospectively followed up. A total of 440 patients were included. All of them underwent CMR 1 week after admission. CMR-derived LVEF and IS (grams per meter squared) were quantified. AACEs included postdischarge sudden death, sustained ventricular tachycardia, and ventricular fibrillation either documented on ECG or recorded via an implantable cardioverter-defibrillator. Within a median follow-up of 2 years, 11 AACEs (2.5%) were detected: 5 sudden deaths (1.1%) and 6 spontaneous ventricular tachycardia/ventricular fibrillation. In the whole group, AACEs associated with more depressed LVEF (adjusted hazard ratio [95% confidence interval], 0.90 [0.83-0.97]; P<0.01) and larger IS (adjusted hazard ratio [95% confidence interval], 1.06 [1.01-1.12]; P=0.01). According to the corresponding area under the receiver operating characteristic curve, LVEF ≤36% and IS ≥23.5 g/m(2) best predicted AACEs. The vast majority of AACEs (10/11) occurred in patients with simultaneous depressed LVEF ≤36% and IS ≥23.5 g/m(2) (n=39).

CONCLUSIONS

In the era of reperfusion therapies, occurrence of AACEs in patients with an in-hospital noncomplicated first ST-segment-elevation myocardial infarction is low. In this setting, assessment of an early CMR-derived IS could be useful for further optimization of AACE risk prediction.

Contrast-enhancement cardiac magnetic resonance imaging beyond the scope of viability

The clinical applications of cardiovascular magnetic resonance imaging with contrast enhancement are expanding. Besides the direct visualisation of viable and non-viable myocardium, this technique is increasingly used in a variety of cardiac disorders to determine the exact aetiology, guide proper treatment, and predict outcome and prognosis. In this review, we discuss the value of cardiovascular magnetic resonance imaging with contrast enhancement in a range of cardiac disorders, in which this technique may provide insights beyond the scope of myocardial viability.

Tachycardia in post-infarction hearts: insights from 3D image-based ventricular models

Ventricular tachycardia, a life-threatening regular and repetitive fast heart rhythm, frequently occurs in the setting of myocardial infarction. Recently, the peri-infarct zones surrounding the necrotic scar (termed gray zones) have been shown to correlate with ventricular tachycardia inducibility. However, it remains unknown how the latter is determined by gray zone distribution and size. The goal of this study is to examine how tachycardia circuits are maintained in the infarcted heart and to explore the relationship between the tachycardia organizing centers and the infarct gray zone size and degree of heterogeneity. To achieve the goals of the study, we employ a sophisticated high-resolution electrophysiological model of the infarcted canine ventricles reconstructed from imaging data, representing both scar and gray zone. The baseline canine ventricular model was also used to generate additional ventricular models with different gray zone sizes, as well as models in which the gray zone was represented as different heterogeneous combinations of viable tissue and necrotic scar. The results of the tachycardia induction simulations with a number of high-resolution canine ventricular models (22 altogether) demonstrated that the gray zone was the critical factor resulting in arrhythmia induction and maintenance. In all models with inducible arrhythmia, the scroll-wave filaments were contained entirely within the gray zone, regardless of its size or the level of heterogeneity of its composition. The gray zone was thus found to be the arrhythmogenic substrate that promoted wavebreak and reentry formation. We found that the scroll-wave filament locations were insensitive to the structural composition of the gray zone and were determined predominantly by the gray zone morphology and size. The findings of this study have important implications for the advancement of improved criteria for stratifying arrhythmia risk in post-infarction patients and for the development of new approaches for determining the ablation targets of infarct-related tachycardia.

Multi-contrast late enhancement CMR determined gray zone and papillary muscle involvement predict appropriate ICD therapy in patients with ischemic heart disease

BACKGROUND

Myocardial infarct heterogeneity indices including peri-infarct gray zone are predictors for spontaneous ventricular arrhythmias events after ICD implantation in patients with ischemic heart disease. In this study we hypothesize that the extent of peri-infarct gray zone and papillary muscle infarct scores determined by a new multi-contrast late enhancement (MCLE) method may predict appropriate ICD therapy in patients with ischemic heart disease.

METHODS

The cardiovascular magnetic resonance (CMR) protocol included LV functional parameter assessment and late gadolinium enhancement (LGE) CMR using the conventional method and MCLE post-contrast. The proportion of peri-infarct gray zone, core infarct, total infarct relative to LV myocardium mass, papillary muscle infarct scores, and LV functional parameters were statistically compared between groups with and without appropriate ICD therapy during follow-up.

RESULTS

Twenty-five patients with prior myocardial infarct for planned ICD implantation (age 64±10 yrs, 88% men, average LVEF 26.2±10.4%) were enrolled. All patients completed the CMR protocol and 6-46 months follow-up at the ICD clinic. Twelve patients had at least one appropriate ICD therapy for ventricular arrhythmias at follow-up. Only the proportion of gray zone measured with MCLE and papillary muscle infarct scores demonstrated a statistically significant difference (P < 0.05) between patients with and without appropriate ICD therapy for ventricular arrhythmias; other CMR derived parameters such as LVEF, core infarct and total infarct did not show a statistically significant difference between these two groups.

CONCLUSIONS

Peri-infarct gray zone measurement using MCLE, compared to using conventional LGE-CMR, might be more sensitive in predicting appropriate ICD therapy for ventricular arrhythmia events. Papillary muscle infarct scores might have a specific role for predicting appropriate ICD therapy although the exact mechanism needs further investigation.

The prognostic role of late gadolinium enhancement magnetic resonance imaging in patients with cardiomyopathy

Cardiovascular magnetic resonance imaging (CMRI) is currently considered part of standard care at many academic centres for the evaluation of patients with ischemic or nonischemic cardiomyopathy. While CMRI provides unparalleled diagnostic versatility for the assessment of myocardial function, perfusion, and tissue health, evidence supporting its prognostic value for the prediction of important cardiovascular events is now emerging. Given the low specificity of currently available clinical markers in patients with cardiomyopathy, more-robust biomarkers aimed at identifying those at high risk of sudden cardiac death and other relevant outcomes are desirable. Late gadolinium enhancement (LGE) CMRI offers the novel capacity to quantify the burden of myocardial fibrosis, a common pathophysiological end point of most cardiomyopathy states. As such, it has the potential to be a robust and ubiquitous marker of cardiovascular events related to the presence of advanced tissue disease. This review paper focuses on the evidence to date supporting LGE imaging as a tool for the prediction of future cardiovascular events in patients with ischemic and nonischemic cardiomyopathy.

Cardiac MRI of acute coronary syndrome

Acute coronary syndrome (ACS) is a major cause of morbidity and mortality worldwide. New serological biomarkers, such as troponins, have improved the diagnosis of ACS; however, the diagnosis of ACS can still be difficult as there is marked heterogeneity in its presentation and significant overlap with other disorders presenting with chest pain. Evidence is accumulating that cardiac MRI provides information that can aid the detection and differential diagnosis of ACS, guide clinical decision-making and improve risk-stratification after an event. In this review, we present the relevant cardiac MRI techniques that can be used to detect ACS accurately, provide differential diagnosis, identify the sequelae of ACS, and determine prognostication after ACS.

Cardiac MRI scar patterns differ by sex in an implantable cardioverter-defibrillator and cardiac resynchronization therapy cohort

BACKGROUND

Recent meta-analyses suggest that the effectiveness of cardiac devices may differ between genders. Compared to men, women may not benefit as much from implantable cardioverter-defibrillators (ICDs), yet benefit more from cardiac resynchronization therapy (CRT). Myocardial scar burden is associated with increased incidence of appropriate ICD shocks but decreased response to CRT and may explain gender differences in device benefit.

OBJECTIVE

To test the hypothesis that the extent of myocardial scar is less in women than men.

METHODS

In 235 patients referred for primary prevention ICDs who underwent cardiac magnetic resonance imaging, we compared scar size by gender. Analyses were performed for all patients (ICD cohort) and those receiving biventricular pacemakers (CRT subgroup).

RESULTS

In the ICD cohort, women (vs men) had a higher prevalence of nonischemic cardiomyopathy (NICM; 64% vs 39%; P<.001), which accounted for a smaller overall scar burden (0.5% vs 13%, P<.01). Likewise, in the CRT subgroup, the higher prevalence of NICM in women (83% vs 46%; P = .01) also contributed to a smaller scar size (0% vs 13%; P<.01). Women also had significantly less scarring of the inferolateral left ventricular wall.

CONCLUSIONS

In a cohort of patients undergoing clinically indicated ICD and CRT, women had less myocardial scar than did men. This difference was primarily driven by a higher prevalence of NICM in women. These findings may have important implications for the future study of gender disparities in ICD and CRT outcomes.

Feasibility of image-based simulation to estimate ablation target in human ventricular arrhythmia

BACKGROUND

Previous studies suggest that magnetic resonance imaging with late gadolinium enhancement (LGE) may identify slowly conducting tissues in scar-related ventricular tachycardia (VT).

OBJECTIVE

To test the feasibility of image-based simulation based on LGE to estimate ablation targets in VT.

METHODS

We conducted a retrospective study in 13 patients who had preablation magnetic resonance imaging for scar-related VT ablation. We used image-based simulation to induce VT and estimate target regions according to the simulated VT circuit. The estimated target regions were coregistered with the LGE scar map and the ablation sites from the electroanatomical map in the standard ablation approach.

RESULTS

In image-based simulation, VT was inducible in 12 (92.3%) patients. All VTs showed macroreentrant propagation patterns, and the narrowest width of estimated target region that an ablation line should span to prevent VT recurrence was 5.0 ± 3.4 mm. Of 11 patients who underwent ablation, the results of image-based simulation and the standard approach were consistent in 9 (82%) patients, where ablation within the estimated target region was associated with acute success (n = 8) and ablation outside the estimated target region was associated with failure (n = 1). In 1 (9%) case, the results of image-based simulation and the standard approach were inconsistent, where ablation outside the estimated target region was associated with acute success.

CONCLUSIONS

The image-based simulation can be used to estimate potential ablation targets of scar-related VT. The image-based simulation may be a powerful noninvasive tool for preprocedural planning of ablation procedures to potentially reduce the procedure time and complication rates.

Scar heterogeneity on cardiovascular magnetic resonance as a predictor of appropriate implantable cardioverter defibrillator therapy

BACKGROUND

Despite the survival benefit of implantable-cardioverter-defibrillators (ICDs), the vast majority of patients receiving an ICD for primary prevention do not receive ICD therapy. We sought to assess the role of heterogeneous scar area (HSA) identified by late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) in predicting appropriate ICD therapy for primary prevention of sudden cardiac death (SCD).

METHODS

From September 2003 to March 2011, all patients who underwent primary prevention ICD implantation and had a pre-implantation LGE-CMR were identified. Scar size was determined using thresholds of 4 and 6 standard deviations (SD) above remote normal myocardium; HSA was defined using 3 different criteria; as the region between 2 SD and 4 SD (HSA2-4SD), between 2SD and 6SD (HSA2-6SD), and between 4SD and 6SD (HSA4-6SD). The end-point was appropriate ICD therapy.

RESULTS

Out of 40 total patients followed for 25 ± 24 months, 7 had appropriate ICD therapy. Scar size measured by different thresholds was similar in ICD therapy and non-ICD therapy groups (P = NS for all). However, HSA2-4SD and HSA4-6SD were significantly larger in the ICD therapy group (P = 0.001 and P = 0.03, respectively). In multivariable model HSA2-4SD was the only significant independent predictor of ICD therapy (HR = 1.08, 95%CI: 1.00-1.16, P = 0.04). Kaplan-Meier analysis showed that patients with greater HSA2-4SD had a lower survival free of appropriate ICD therapy (P = 0.026).

CONCLUSIONS

In primary prevention ICD implantation, LGE-CMR HSA identifies patients with appropriate ICD therapy. If confirmed in larger series, HSA can be used for risk stratification in primary prevention of SCD.

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.

Prognostic role of CMR in patients presenting with ventricular arrhythmias

OBJECTIVES

The goal of this study was to explore whether fibrosis detected by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is an independent predictor of hard cardiovascular events in patients presenting with ventricular arrhythmia.

BACKGROUND

In patients at risk of sudden cardiac death, risk stratification for device therapy remains challenging.

METHODS

A total of 373 consecutive patients with sustained ventricular tachycardia (VT) (n = 204) or nonsustained ventricular tachycardia (NSVT) (n = 169) underwent LGE-CMR. The group was prospectively followed up for a median of 2.6 years (range 11 months to 11 years). The predetermined endpoint was a composite of cardiac death/arrest, new episode of sustained VT, or appropriate implantable cardioverter-defibrillator discharge.

RESULTS

Mean left ventricular (LV) ejection fraction (EF) was 60 ± 13%. The presence of fibrosis was a strong and independent predictor of the primary outcome for the whole group (hazard ratio [HR]: 3.3, 95% confidence interval [CI]: 1.8 to 5.8, p < 0.001). In the sustained VT subset, both LV fibrosis and severely impaired systolic function (LVEF <35%) were significant independent predictors in the multivariate model (HR: 3.0, 95% CI: 1.4 to 6.2, p = 0.001; and HR: 2.5, 95% CI: 1.1 to 6.2, p = 0.038, respectively). In the NSVT subset, the presence of fibrosis was the only independent predictor of the endpoint (HR: 4.2, 95% CI: 1.7 to 10.1, p = 0.006).

CONCLUSIONS

LGE-CMR-detected fibrosis is an independent predictor of adverse outcomes in patients with ventricular arrhythmia and may have an important role in risk stratification. (The Prognostic Significance of Fibrosis Detection in Ischemic and Non-Ischemic Cardiomyopathy; NCT00930735).

Scar extent evaluated by late gadolinium enhancement CMR: a powerful predictor of long term appropriate ICD therapy in patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) patients are at risk for life-threatening ventricular arrhythmias (VA) related to scar tissue. Late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) can accurately identify myocardial scar extent. It has been shown that scar extent, particularly scar transmurality, percent scar and scar mass, are associated with the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapy. However, quantification of transmurality extent has never been studied. The purpose of our study was to evaluate whether different methods quantifying scar transmurality, percent scar and scar mass (assessed with LGE-CMR) can predict appropriate ICD therapy in CAD patients with a long term follow-up period.

METHODS AND RESULTS

We enrolled retrospectively 66 patients with chronic CAD referred for primary or secondary preventive ICD implantation and LGE-CMR before ICD implantation. Using LGE-CMR, scar extent was assessed by measuring scar mass, percent scar and transmural scar extent using four different methods. The median follow-up duration was 41.5 months (interquartile range 22-52). The endpoint was the occurrence of appropriate device therapy and occurred in 14 patients. Pre-ICD revascularization and transmural scar extent were significantly associated with the study endpoint but the latter was especially highly dependent on the method used. Patients with appropriate device therapy had also larger scar mass (29.6 ± 14.5 g vs 17.1 ± 8.8 g, p = 0.004), and larger percent scar (15.1 ± 8.2% vs 9.9 ± 5.6%, p = 0.03) than patients without appropriate device therapy. In multivariate analysis, scar extent variables remained significantly associated with the study end-point.

CONCLUSIONS

In this study of CAD patients implanted for primary or secondary preventive ICD, pre-ICD revascularization and scar extent studied by LGE-CMR were significantly associated with appropriate device therapy and can identify a subgroup of CAD patients with an increased risk of life-threatening VA. Depending of the method used, transmural scar extent may vary significantly and needs further studies to obtain a validated and consensual study method.

Prediction of ventricular arrhythmias using cardiovascular magnetic resonance

Ventricular tachycardia (VT) is the commonest cause of sudden cardiac death (SCD) in developed countries. Coronary artery disease (CAD) is the most frequent cause of VT in individuals over the age of 30, while hypertrophic cardiomyopathy (HCM), myocarditis and congenital heart disease in those below 30 years of age. Cardiac magnetic resonance (CMR), a non-invasive, non-radiating technique, can reliably detect the changes in ventricular volumes and the ejection fraction that can be predictive of VT/SCD. Furthermore, the capability of CMR to perform tissue characterization and detect oedema, fat and fibrotic substrate, using late gadolinium enhanced images (LGE), can predict VT/SCD in both ischaemic and non-ischaemic cardiomyopathy. The extent of LGE in HCM is correlated with risk factors of SCD and the likelihood of inducible VT. In idiopathic-dilated cardiomyopathy, the presence of midwall fibrosis, assessed by CMR, also predicts SCD/VT. Additionally, in arrhythmogenic right ventricle (RV) dysplasia/cardiomyopathy, CMR has an excellent correlation with histopathology and predicted inducible VT on programmed electrical stimulation, suggesting a possible role in evaluation and diagnosis of these patients. A direct correlation between LGE and VT prediction has been identified only in chronic Chagas' heart disease, but not in viral myocarditis. In CAD, infarct size is the strongest predictor of VT inducibility. The peri-infarct zone may also play a role; however, further studies are needed for definite conclusions. Left ventricle, RV, right ventricular outflow tract (RVOT) function, pulmonary regurgitation and LGE around the infundibular patch and RV anterior wall play an important role in the VT prediction in repaired Tetralogy of Fallot. Finally, in treated transposition of great arteries, the extent of LGE in the systemic RV correlates with age, ventricular dysfunction, electrophysiological parameters and adverse clinical events, suggesting prognostic importance.

Assessment of Myocardial Contractile Function Using Global and Segmental Circumferential Strain following Intracoronary Stem Cell Infusion after Myocardial Infarction: MRI Feature Tracking Feasibility Study

Background. Magnetic resonance imaging (MRI) strain analysis is a sensitive method to assess myocardial function. Our objective was to define the feasibility of MRI circumferential strain (ε_cc) analysis in assessing subtle changes in myocardial function following stem cell therapy. Methods and Results. Patients in the Amorcyte Phase I trial were randomly assigned to treatment with either autologous bone-marrow-derived stem cells infused into the infarct-related artery 5 to 11 days following primary PCI or control. MRI studies were obtained at baseline, 3, and 6 months. ε_cc was measured in the short axis views at the base, mid and apical slices of the left ventricle (LV) for each patient (13 treatments and 10 controls). Mid-anterior LV ε_cc improved between baseline −18.5 ± 8.6 and 3 months −22.6 ± 7.0, P = 0.03. There were no significant changes in ε_cc at 3 months and 6 months compared to baseline for other segments. There was excellent intraobserver and interobserver agreement for basal and mid circumferential strain. Conclusion. MRI segmental strain analysis is feasible in assessment of regional myocardial function following cell therapy with excellent intra- and inter-observer variability's. Using this method, a modest interval change in segmental ε_cc was detected in treatment group.

Automated quantification of myocardial infarction using graph cuts on contrast delayed enhanced magnetic resonance images

In this work, we propose a semi-automated myocardial infarction quantification method for cardiac contrast delayed enhancement magnetic resonance images (DE-MRI). Advantages of this method include that it reduces manual contouring of the left ventricle, obviates a remote myocardium region, and automatically distinguishes infarct, healthy and heterogeneous ("gray zone") tissue despite variability in intensity and noise across images. Quantitative evaluation results showed that the automatically determined infarct core and gray zone size have high correlation with that derived from the averaged results of the manual full width at half maximum (FWHM) methods (R(2)=0.99 for infarct core and gray zone size). Compared with the manual method, a much better reproducibility was achieved with the proposed algorithm and it shortens the evaluation time to one second per image, compared with 2-5 min per image for the manual method.

Relationship between infarct tissue characteristics and left ventricular remodeling in patients with versus without early revascularization for acute myocardial infarction as assessed with contrast-enhanced cardiovascular magnetic resonance imaging

Left ventricular (LV) remodeling following myocardial infarction (MI) is the result of complex interactions between various factors, including presence or absence of early revascularization. The impact of early revascularization on the relationship between infarct tissue characteristics and LV remodeling is incompletely known. Therefore, we investigated in patients with versus without successful early revascularization for acute MI potential relations between infarct tissue characteristics and LV remodeling with contrast-enhanced (CE) cardiovascular magnetic resonance (CMR). Patients with versus without successful early revascularization underwent CE-CMR for tissue characterization and assessment of LV remodeling including end-diastolic and end-systolic volumes, LV ejection fraction, and wall motion score index (WMSI). CE-CMR images were analyzed for infarct tissue characteristics including core-, peri- and total-infarct size, transmural extent, and regional scar scores. In early revascularized patients (n = 46), a larger area of infarct tissue correlated significantly with larger LV dimensions and a more reduced LV function (r = 0.39-0.68; all P ≤ 0.01). Multivariate analyses identified peri-infarct size as the best predictor of LV remodeling parameters (R(2 )= 0.44-0.62). In patients without successful early revascularization (n = 47), there was no correlation between infarct area and remodeling parameters; only peri-infarct size versus WMSI (r = 0.33; P = 0.03) and transmural extent versus LVEF (r = -0.27; P = 0.07) tended to be related. A correlation between infarct tissue characteristics and LV remodeling was found only in patients with early successful revascularization. Peri-infarct size was found to be the best determinant of LV remodeling. Our findings stress the importance of taking into account infarct tissue characteristics and success of revascularization when LV remodeling is studied.

Integration of merged delayed-enhanced magnetic resonance imaging and multidetector computed tomography for the guidance of ventricular tachycardia ablation: a pilot study

BACKGROUND

Delayed enhancement (DE) MRI can assess the fibrotic substrate of scar-related VT. MDCT has the advantage of inframillimetric spatial resolution and better 3D reconstructions. We sought to evaluate the feasibility and usefulness of integrating merged MDCT/MRI data in 3D-mapping systems for structure-function assessment and multimodal guidance of VT mapping and ablation.

METHODS

Nine patients, including 3 ischemic cardiomyopathy (ICM), 3 nonischemic cardiomyopathy (NICM), 2 myocarditis, and 1 redo procedure for idiopathic VT, underwent MRI and MDCT before VT ablation. Merged MRI/MDCT data were integrated in 3D-mapping systems and registered to high-density endocardial and epicardial maps. Low-voltage areas (<1.5 mV) and local abnormal ventricular activities (LAVA) during sinus rhythm were correlated to DE at MRI, and wall-thinning (WT) at MDCT.

RESULTS

Endocardium and epicardium were mapped with 391 ± 388 and 1098 ± 734 points per map, respectively. Registration of MDCT allowed visualization of coronary arteries during epicardial mapping/ablation. In the idiopathic patient, integration of MRI data identified previously ablated regions. In ICM patients, both DE at MRI and WT at MDCT matched areas of low voltage (overlap 94 ± 6% and 79 ± 5%, respectively). In NICM patients, wall-thinning areas matched areas of low voltage (overlap 63 ± 21%). In patients with myocarditis, subepicardial DE matched areas of epicardial low voltage (overlap 92 ± 12%). A total number of 266 LAVA sites were found in 7/9 patients. All LAVA sites were associated to structural substrate at imaging (90% inside, 100% within 18 mm).

CONCLUSION

The integration of merged MDCT and DEMRI data is feasible and allows combining substrate assessment with high-spatial resolution to better define structure-function relationship in scar-related VT.

Epicardial ablation for ventricular tachycardia

Epicardial ablation has lately become a necessary tool to approach some ventricular tachycardias in different types of cardiomyopathy. Its diffusion is now limited to a few high volume centers not because of the difficulty of the pericardial puncture but since it requires high competence not only in the VT ablation field but also in knowing and recognizing the possible complications each of which require a careful treatment.

This article will review the state of the art of epicardial ablation with special attention to the procedural aspects and to the possible selection criteria of the patients

Myocardial structural associations with local electrograms: a study of postinfarct ventricular tachycardia pathophysiology and magnetic resonance-based noninvasive mapping

BACKGROUND

The association of scar on late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) with local electrograms on electroanatomic mapping has been investigated. We aimed to quantify these associations to gain insights regarding LGE-CMR image characteristics of tissues and critical sites that support postinfarct ventricular tachycardia (VT).

METHODS AND RESULTS

LGE-CMR was performed in 23 patients with ischemic cardiomyopathy before VT ablation. Left ventricular wall thickness and postinfarct scar thickness were measured in each of 20 sectors per LGE-CMR short-axis plane. Electroanatomic mapping points were retrospectively registered to the corresponding LGE-CMR images. Multivariable regression analysis, clustered by patient, revealed significant associations among left ventricular wall thickness, postinfarct scar thickness, and intramural scar location on LGE-CMR, and local endocardial electrogram bipolar/unipolar voltage, duration, and deflections on electroanatomic mapping. Anteroposterior and septal/lateral scar localization was also associated with bipolar and unipolar voltage. Antiarrhythmic drug use was associated with electrogram duration. Critical sites of postinfarct VT were associated with >25% scar transmurality, and slow conduction sites with >40 ms stimulus-QRS time were associated with >75% scar transmurality.

CONCLUSIONS

Critical sites for maintenance of postinfarct VT are confined to areas with >25% scar transmurality. Our data provide insights into the structural substrates for delayed conduction and VT and may reduce procedural time devoted to substrate mapping, overcome limitations of invasive mapping because of sampling density, and enhance magnetic resonance-based ablation by feature extraction from complex images.

Cardiovascular magnetic resonance imaging in ischemic heart disease

Ischemic heart disease is the most frequent etiology for cardiovascular morbidity and mortality. Early detection and accurate monitoring are essential to guide optimal patient treatment and assess the individual's prognosis. In this regard, cardiovascular magnetic resonance (CMR), which entered the arena of noninvasive cardiovascular imaging over the past two decades, became a very important imaging modality, mainly due to its unique versatility. CMR has proven accuracy and is a robust technique for the assessment of myocardial function both at rest and during stress. It also allows stress perfusion analysis with high spatial and temporal resolution, and provides a means by which to differentiate tissue such as distinguishing between reversibly and irreversibly injured myocardium. In particular, the latter aspect is a unique benefit of CMR compared with other noninvasive imaging modalities such as echocardiography and nuclear medicine, and provides novel information concerning the presence, size, transmurality, and prognosis of myocardial infarction. This article is intended to provide the reader with an overview of the various applications of CMR for the assessment of ischemic heart disease from a clinical perspective.

CKD and sudden cardiac death: epidemiology, mechanisms, and therapeutic approaches

Multiple studies demonstrate a strong independent association between CKD and cardiovascular events including death, heart failure, and myocardial infarction. This review focuses on recent clinical studies that expand this spectrum of adverse cardiovascular events to include ventricular arrhythmias and sudden cardiac death. In addition, experimental models suggest structural remodeling of the heart and electrophysiologic changes in this population. These processes may explain the increased arrhythmic risk in kidney disease and aid in identifying patients who are at higher risk for sudden cardiac death. Finally, we review here the data to support the use of pharmacologic and device-based therapies for both the primary and secondary prevention of sudden cardiac death.

Accelerated late gadolinium enhancement cardiac MR imaging with isotropic spatial resolution using compressed sensing: initial experience

PURPOSE

To evaluate the use of low-dimensional-structure self-learning and thresholding (LOST) compressed sensing acquisition and reconstruction in the assessment of left atrial (LA) and left ventricular (LV) scar by using late gadolinium enhancement (LGE) magnetic resonance (MR) imaging with isotropic spatial resolution.

MATERIALS AND METHODS

The study was approved by the local institutional review board and was compliant with HIPAA. All subjects provided written informed consent. Twenty-eight patients (eight women; mean age, 58.0 years ± 10.1) with a history of atrial fibrillation were recruited for the LA LGE study, and 14 patients (five women; mean age, 54.2 years ± 18.6) were recruited for assessment of LV myocardial infarction. With use of a pseudorandom k-space undersampling pattern, threefold accelerated three-dimensional (3D) LGE data were acquired with isotropic spatial resolution and reconstructed off-line by using LOST. For comparison, subjects were also imaged by using standard 3D LGE protocols with nonisotropic spatial resolution. Images were compared qualitatively by three cardiologists with regard to diagnostic value, presence of enhancement, and image quality. The signed rank test and Wilcoxon unpaired two-sample test were used to test the hypothesis that there would be no significant difference in image quality ratings with different resolutions.

RESULTS

Interpretable images were obtained in 26 of the 28 patients (93%) in the LA LGE study. LGE was seen in 17 of 30 cases (57%) with nonisotropic resolution and in 18 cases (60%) with isotropic resolution. Diagnostic quality scores of isotropic images were significantly higher than those of nonisotropic images with coronal views (median, 3 vs 2, respectively [25th and 75th percentiles: 3, 3 vs 2, 3]; P < .001) and sagittal views (median, 3 vs 2 [25th and 75th percentiles: 3, 4 vs 2, 3]; P < .001) but lower with axial views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 3, 3]; P < .001). For the LV LGE study, all patients had interpretable images. LGE was seen in six of 14 patients (43%), with 100% agreement between both data sets. Diagnostic quality scores of high-isotropic-resolution LV images were higher than those of nonisotropic images with short-axis views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 2, 3]; P = .014) and two-chamber views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 2, 3]; P = .001).

CONCLUSION

An accelerated LGE acquisition with LOST enables imaging with high isotropic spatial resolution for improved assessment of LV, LA, and pulmonary vein scar.

Cardiac MRI in the diagnosis of complications of myocardial infarction

The improvement in revascularization techniques and medicine treatment during infarction has substantially reduced mortality during the acute phase of this condition. Since the advent of kinetic sequences and the concomitant development of gadolinium chelates and delayed enhancement sequences, cardiac MRI has become the second-line reference examination for ischemic heart disease. The technique of delayed enhancement with the inversion recovery sequence performed after injection has been validated for numerous indications in ischemic disease. Delayed enhancement sequences make it possible in particular to look for "no-reflow" areas (microvascular obstructions), to quantify the infarction area, and to assess prognosis. MRI also allows us to define the area at risk, that is, the area with edema, and to look for and assess the mechanical complications of the infarction. The aim of this review is to summarize current knowledge about: the pharmacokinetic principles that regulate myocardial enhancement; the different sequences available to acquire delayed enhancement images, and; the value of cardiac MRI in the diagnosis of complications of myocardial infarction.

Cardiac MRI visualization for ventricular tachycardia ablation

OBJECTIVE

The integrated visualization of cardiac MRI during a ventricular tachycardia (VT) mapping and ablation procedure would provide improved catheter guidance and tissue assessment. We developed a system for and explored the added value of simultaneous visualization of intracardiac voltage measurements and MRI-derived myocardial scar information during VT ablation procedures.

METHOD

We propose the use of a synchronized 3D and 2D view. In 3D, the catheter will be guided optimally by assessing 3D scar characteristics and its relation to the ventricular anatomy. In 2D, a detailed assessment of the tissue can be made. We developed several 3D visualization techniques, including volume rendering of the scar and myocardial surfaces colored according to the voltage measurements. We also visualized context structures in the heart. For the 2D view, we proposed showing three adjacent slices simultaneously. To link the 3D with the 2D view, we added a linking plane and linking contours; the slice level shown in the 2D view is indicated in the 3D view.

RESULTS

We evaluated our method via a case study during which we simulated the visual environment of an ablation procedure. The MRI-based volume rendering of scar tissue and the linking between the 3D and 2D views were both positively received. However, the visualization of the voltage measurements was found to be hard to interpret, partly due to the perceptually suitable but non-standard colormap.

CONCLUSIONS

Based on this study, we can conclude that our approach of displaying MRI data and integrating it with voltage measurements has potential to improve VT ablation procedures.

Potential of delayed gadolinium enhancement magnetic resonance imaging for quantification of reverse remodeling of the peri-infarct zone in patients with ischemic cardiomyopathy treated with chronic vasodilator therapy: initial experience

PURPOSE

The peri-infarct zone represents the morphologic substrate for reentry ventricular tachycardia after myocardial infarction, and its extent is a strong predictor of major cardiac events. Although delayed gadolinium enhancement magnetic resonance imaging (DGE-MRI) was shown to allow for detailed characterization of myocardial infarction by quantifying infarct core zone and peri-infarct zone volume, potentials of DGE-MRI for measuring changes in peri-infarct zone volume are unknown. Therefore, we aimed to assess changes in volume of the peri-infarct zone among patients with ischemic cardiomyopathy treated with chronic vasodilator therapy.

MATERIALS AND METHODS

Core and peri-infarct zone volumes as assessed with DGE-MRI were measured in 5 patients at baseline and after 6 months treatment with sustained-release dipyridamole.

RESULTS

Core zone volume remained stable during follow-up [median (range), 19 mL (9 to 42) vs. 16 mL (11 to 46); P=0.785]. The ratio between the peri-infarct zone and the core zone volume decreased significantly at 6 months compared with baseline [median (range), 0.22 (0.19 to 0.42) vs. 0.18 (0.09 to 0.32); P=0.043], and a trend toward reduction in peri-infarct zone volume was found [median (range), 5 mL (2 to 8) vs. 3 mL (2 to 6); P=0.059]. The peri-infarct zone volume decreased in all but 1 patient over the follow-up.

CONCLUSIONS

This initial experience suggests that reverse remodeling of the peri-infarct zone with reduction in peri-infarct zone volume may take place in patients with ischemic cardiomyopathy. Quantification of this process may be feasible with DGE-MRI, but further studies are needed to confirm this hypothesis and to further clarify the role of DGE-MRI for the assessment of changes in peri-infarct zone volume in patients with ischemic cardiomyopathy.

Infarct tissue characterization in implantable cardioverter-defibrillator recipients for primary versus secondary prevention following myocardial infarction: a study with contrast-enhancement cardiovascular magnetic resonance imaging

Knowledge about potential differences in infarct tissue characteristics between patients with prior life-threatening ventricular arrhythmia versus patients receiving prophylactic implantable cardioverter-defibrillator (ICD) might help to improve the current risk stratification in myocardial infarction (MI) patients who are considered for ICD implantation. In a consecutive series of (ICD) recipients for primary and secondary prevention following MI, we used contrast-enhanced (CE) cardiovascular magnetic resonance (CMR) imaging to evaluate differences in infarct tissue characteristics. Cine-CMR measurements included left ventricular end-diastolic and end-systolic volumes (EDV, ESV), left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and mass. CE-CMR images were analyzed for core, peri, and total infarct size, infarct localization (according to coronary artery territory), and transmural extent. In this study, 95 ICD recipients were included. In the primary prevention group (n = 66), LVEF was lower (23 ± 9 % vs. 31 ± 14 %; P < 0.01), ESV and WMSI were higher (223 ± 75 ml vs. 184 ± 97 ml, P = 0.04, and 1.89 ± 0.52 vs. 1.47 ± 0.68; P < 0.01), and anterior infarct localization was more frequent (P = 0.02) than in the secondary prevention group (n = 29). There were no differences in infarct tissue characteristics between patients treated for primary versus secondary prevention (P > 0.6 for all). During 21 ± 9 months of follow-up, 3 (5 %) patients in the primary prevention group and 9 (31 %) in the secondary prevention group experienced appropriate ICD therapy for treatment of ventricular arrhythmia (P < 0.01). There was no difference in infarct tissue characteristics between recipients of ICD for primary versus secondary prevention, while the secondary prevention group showed a higher frequency of applied ICD therapy for ventricular arrhythmia.

Virtual electrophysiological study in a 3-dimensional cardiac magnetic resonance imaging model of porcine myocardial infarction

OBJECTIVES

This study sought to test the hypothesis that "virtual" electrophysiological studies (EPS) on an anatomic platform generated by 3-dimensional magnetic resonance imaging reconstruction of the left ventricle can reproduce the reentrant circuits of induced ventricular tachycardia (VT) in a porcine model of myocardial infarction.

BACKGROUND

Delayed-enhancement magnetic resonance imaging has been used to characterize myocardial infarction and "gray zones," which are thought to reflect heterogeneous regions of viable and nonviable myocytes.

METHODS

Myocardial infarction by coronary artery occlusion was induced in 8 pigs. After a recovery period, 3-dimensional cardiac magnetic resonance images were obtained from each pig in vivo. Normal areas, gray zones, and infarct cores were classified based on voxel intensity. In the computer model, gray zones were assigned slower conduction and longer action potential durations than those for normal myocardium. Virtual EPS was performed and compared with results of actual in vivo programmed stimulation and noncontact mapping.

RESULTS

The left ventricular volumes ranged from 97.8 to 166.2 cm(3), with 4.9% to 17.5% of voxels classified as infarct zones. Six of the 7 pigs in which VT developed during actual EPS were also inducible with virtual EPS. Four of the 6 pigs that had simulated VT had reentrant circuits that approximated the circuits seen with noncontact mapping, whereas the remaining 2 had similar circuits but propagating in opposite directions.

CONCLUSIONS

This initial study demonstrates the feasibility of applying a mathematical model to magnetic resonance imaging reconstructions of the left ventricle to predict VT circuits. Virtual EPS may be helpful to plan catheter ablation strategies or to identify patients who are at risk of future episodes of VT.

Prediction of arrhythmic events in ischemic and dilated cardiomyopathy patients referred for implantable cardiac defibrillator: evaluation of multiple scar quantification measures for late gadolinium enhancement magnetic resonance imaging

BACKGROUND

Scar signal quantification using late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) identifies patients at higher risk of future events, both in ischemic cardiomyopathy (ICM) and nonischemic dilated cardiomyopathy (DCM). However, the ability of scar signal burden to predict events in such patient groups at the time of referral for implantable cardioverter-defibrillator (ICD) has not been well explored. This study evaluates the predictive use of multiple scar quantification measures in ICM and DCM patients being referred for ICD.

METHODS AND RESULTS

One hundred twenty-four consecutive patients referred for ICD therapy (59 with ICM and 65 with DCM) underwent a standardized LGE-CMR protocol with blinded, multithreshold scar signal quantification and, for those with ICM, peri-infarct signal quantification. Patients were followed prospectively for the primary combined outcome of appropriate ICD therapy, survived cardiac arrest, or sudden cardiac death. At a mean follow-up of 632 ± 262 days, 18 patients (15%) had suffered the primary outcome. Total scar was significantly higher among those suffering a primary outcome, a relationship maintained within each cardiomyopathy cohort (P<0.01 for all comparisons). Total scar was the strongest independent predictor of the primary outcome and demonstrated a negative predictive value of 86%. In the ICM subcohort, peri-infarct signal showed only a nonsignificant trend toward elevation among those having a primary end point.

CONCLUSIONS

Myocardial scar quantification by LGE-CMR predicts arrhythmic events in patients being evaluated for ICD eligibility irrespective of cardiomyopathy etiology.