Implantable Cardioverter Defibrillator Eligibility Research Articles

Assessment of ICD eligibility in non-ischaemic cardiomyopathy patients: aposition statement by the Task Force of the Dutch Society of Cardiology.

International guidelines recommend implantation of an implantable cardioverter-defibrillator (ICD) in non-ischaemic cardiomyopathy (NICM) patients with aleft ventricular ejection fraction (LVEF) below 35% despite optimal medical therapy and alife expectancy of more than 1year with good functional status. We propose refinement of these recommendations in patients with NICM, with careful consideration of additional risk parameters for both arrhythmic and non-arrhythmic death. These additional parameters include late gadolinium enhancement on cardiac magnetic resonance imaging and genetic testing for high-risk genetic variants to further assess arrhythmic risk, and age, comorbidities and sex for assessment of non-arrhythmic mortality risk. Moreover, several risk modifiers should be taken into account, such as concomitant arrhythmias that may affect LVEF (atrial fibrillation, premature ventricular beats) and resynchronisation therapy. Even though currently no valid cut-off values have been established, the proposed approach provides amore careful consideration of risks that may result in withholding ICD implantation in patients with low arrhythmic risk and substantial non-arrhythmic mortality risk.

Revascularization and Left Ventricular Dysfunction for ICD Eligibility.

Common triggers for sudden cardiac death (SCD) are transient ischemia, hemodynamic fluctuations, neurocardiovascular influences, and environmental factors. SCD occurs rapidly when sinus rhythm degenerates into ventricular tachycardia (VT) and/or ventricular fibrillation (VF), followed by asystole. Such progressive worsening of the cardiac rhythm is in most cases observed in the setting of ischemic heart disease and often associated with advanced left ventricular (LV) impairment. Revascularization prevents negative outcomes including SCD and heart failure (HF) due to LV dysfunction (LVD). The implantable cardioverter-defibrillator (ICD) on top of medical therapy is superior to antiarrhythmic drugs for patients with LVD and VT/VF. The beneficial effects of ICD have been demonstrated in primary prevention of SCD as well. However, yet debated is the temporal management for patients with LVD who are eligible to ICD prior to revascularization, either through percutaneous or surgical approach. Restoration of coronary blood flow has a dramatic impact on adverse LV remodeling, while it requires aggressive long-term antiplatelet therapy, which might increase complication for eventual ICD procedure when percutaneous strategy is pursued; on the other hand, when LV and/or multiorgan dysfunction is present and coronary artery bypass grafting is chosen, the overall risk is augmented, mostly in HF patients. The aims of this review are to describe the pathophysiologic benefits of revascularization, the studies addressing percutaneous, surgical or no revascularization and ICD implantation, as well as emerging defibrillation strategies for patients deemed at transient risk of SCD and/or at higher risk for transvenous ICD implantation.

Improvement of left ventricular function with surgical revascularization in patients eligible for implantable cardioverter-defibrillator.

Left ventricular ejection fraction (EF) ≤ 35% is the cornerstone criterion for implantable cardioverter-defibrillator (ICD) eligibility. Improvement in EF may occur in ICD-eligible patients after coronary artery bypass graft surgery (CABG). However, the incidence, predictors, and outcomes of this process are unclear. We studied 427 patients with EF ≤ 35% who underwent CABG in the Surgical Treatment for Ischemic Heart Failure (STICH) trial and had a systematic pre- and postoperative (4 months) EF assessment using the identical cardiac imaging modality. All imaging studies were interpreted at a core laboratory. Improvement in EF was defined as postoperative EF > 35% and >5% absolute improvement from baseline. Of the 427 patients (mean age 61.8 ± 9.5 and 50 women), 125 (29.2%) had EF improvement. Their mean EF increased from 26.8% (±5.8%) to 43.3% (±6.5%) (p < .0001). EF improvement occurred in only 20% of patients with a preoperative EF < 25%. The odds of EF improvement were 1.96 times higher (95% confidence interval [CI]: 0.91-4.23, p = .09) in patients with myocardial viability. In adjusted analyses, EF improvement was associated with a significantly lower risk of all-cause mortality (hazard ratio [HR]: 0.58, 95% CI: 0.35-0.96; p = .03) and heart failure mortality (HR: 0.31, 95% CI: 0.11-0.87; p = .027). Nearly 1/3rd of ICD-eligible patients undergoing CABG had significant improvement in EF, obviating the need for primary prevention ICD implantation. These results provide patients and clinicians data on the likelihood of ICD eligibility after CABG and support the practice of reassessment of EF after revascularization.

Abstract 9521: Improvement of Left Ventricular Ejection Fraction After Surgical Revascularization in Patients Eligible for Implantable Cardioverter Defibrillator

Introduction: Left ventricular ejection fraction (LVEF) ≤35% is the cornerstone criterion for implantable cardioverter-defibrillator (ICD) eligibility. But improvement in LVEF may occur in ICD-eligible patients after coronary artery bypass graft surgery (CABG). Methods: We studied the incidence, predictors, and outcomes of LVEF improvement among patients with LVEF ≤35% who underwent CABG as part of the Surgical Treatment for Ischemic Heart Failure (STICH) trial and had pre- and post-operative (4 months) LVEF assessment using the same cardiac imaging modality. Improvement in LVEF was defined as post-operative EF &gt;35% and &gt;5% absolute improvement from baseline. Results: Of the 427 patients (mean age 62±10 and 50 women), 125 (29.2%) had LVEF improvement from 26.8%±5.8% to 43.3%±6.5%; p&lt;0.001. Improvement in LVEF occurred in 20% and 38% of patients with pre-operative LVEF &lt;25% and 30-35%, respectively (Figure). Post-operative improvement in LVEF was 2.20 times more likely in patients with pre-operative LVEF ≥25% (95% CI 1.41-3.43; p&lt;0.001) than those with pre-operative EF &lt;25%. The odds of post-operative LVEF improvement were 1.96 times higher (95% CI 0.91-4.23, p=0.09) in patients with myocardial viability. After adjusting for age, sex, and pre-operative LVEF, improvement in LVEF was associated with a 42% lower risk of all-cause mortality (HR 0.58, 95% CI 0.35-0.96; p=0.03) and 69% lower risk of heart failure mortality (HR 0.31, 95% CI 0.11-0.87; p=0.03). Conclusions: Nearly 1/3 rd of patients with LVEF ≤35% who underwent CABG had a significant improvement in left ventricular systolic function, obviating the need for primary prevention ICD implantation. Post-operative LVEF improvement was associated with a lower risk of death. These results provide patients and clinicians data on the likelihood of ICD eligibility after CABG and support the practice of reassessment of LVEF after revascularization.

The mortality analysis of primary prevention patients receiving a cardiac resynchronization defibrillator (CRT-D) or implantable cardioverter-defibrillator (ICD) according to guideline indications in the improve SCA study.

In primary prevention (PP) patients the utilization of implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapy-defibrillators (CRT-D) remains low in many geographies, despite the proven mortality benefit. The objective of this analysis was to examine the mortality benefit in PP patients by guideline-indicated device type: ICDand CRT-D. Improve sudden cardiac arrest was a prospective, nonrandomized, nonblinded multicenter trial that enrolled patients from regions where ICD utilization is low. PP patient's CRT-D or ICD eligibility was based upon the 2008 ACC/AHA/HRS and 2006 ESC guidelines. Mortality was assessed according to guideline-indicated device type comparing implanted and nonimplanted patients. Cox proportional hazards methods were used, adjusting for known factors affecting mortality risk. Among 2618 PP patients followed for a mean of 20.8 ± 10.8 months, 1073 were indicated for a CRT-D, and 1545 were indicated for an ICD. PP CRT-D-indicated patients who received CRT-D therapy had a 58% risk reduction in mortality compared with those without implant (adjusted hazard ratio [HR]: 0.42, 95% confidence interval [CI]: 0.28-0.61, p < .0001). PP patients with an ICD indication had a 43% risk reduction in mortality with an ICD implant compared with no implant (adjusted HR: 0.57, 95% CI: 0.41-0.81, p = .002). This analysis confirms the mortality benefit of adherence to guideline-indicated implantable defibrillation therapy for PP patients in geographies where ICD therapy was underutilized. These results affirm that medical practice should follow clinical guidelines when choosing therapy for PP patients who meet the respective defibrillator device implant indication.

Sacubitril/Valsartan and Sudden Cardiac Death According to Implantable Cardioverter-Defibrillator Use and Heart Failure Cause: A PARADIGM-HF Analysis

ObjectivesThe purpose of this study was to investigate the effect of sacubitril/valsartan therapy on sudden cardiac death (SCD) according to the use of and eligibility for an implantable cardioverter-defibrillator (ICD), stratified by heart failure cause. BackgroundSCD still accounts for a significant proportion of overall mortality in heart failure with reduced ejection fraction (HFrEF). MethodsPatients enrolled in the PARADIGM-HF (Prospective Comparison of ARNI with an ACE-Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure) trial (n = 8,399) were evaluated to assess patterns of ICD implantation and eligibility according to clinical guidelines. The impact of ICD (adjusted for propensity of ICD implantation) and sacubitril/valsartan therapy on SCD was evaluated by using cause-specific Cox models and competing risk analysis. ResultsAt baseline, of the 7,145 patients (85%) eligible for ICD implantation, only 1,243 (15%) had an ICD. Use of ICD varied by region with the highest rates in North America (56%) and lowest in Asia-Pacific (1.7%). In a propensity score-adjusted analysis, use of an ICD was associated with a 56% lower risk of SCD in ICD-eligible patients, in both patients with ischemic (p < 0.001) and nonischemic cardiomyopathy (p = 0.02). Sacubitril/valsartan reduced SCD risk in patients with an ICD (hazard ratio [HR]: 0.49; 95% confidence interval [CI]: 0.25 to 0.99) and in those who were eligible for but did not receive an ICD (HR: 0.81; 95% CI: 0.67 to 0.98). This effect was particularly evident in nonischemic cardiomyopathy (p < 0.05), although interaction with the cause of HF was not significant (p = 0.11 in subjects using an ICD and p = 0.25 in eligible nonusers). ConclusionsUse of an ICD was associated with lower rates of SCD, regardless of HF cause but was underused in most regions of the world in the PARADIGM-HF study. Sacubitril/valsartan reduced SCD risk regardless of use of an ICD or eligibility, particularly in ICD users and nonischemic cardiomyopathy.

Prediction of sudden cardiac death in Japanese heart failure patients: international validation of the Seattle Proportional Risk Model.

Heart failure (HF) is associated with an increased risk of sudden cardiac death (SCD). This study sought to demonstrate the incidence of SCD within a multicentre Japanese registry of HF patients hospitalized for acute decompensation, and externally validate the Seattle Proportional Risk Model (SPRM). We consecutively registered 2240 acute HF patients from academic institutions in Tokyo, Japan. The discrimination and calibration of the SPRM were assessed by the c-statistic, Hosmer-Lemeshow statistic, and visual plotting among non-survivors. Patient-level SPRM predictions and implantable cardioverter-defibrillator (ICD) benefit [ICD estimated hazard ratio (HR), derived from the Cox proportional hazards model in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)] was calculated. During the 2-year follow-up, 356 deaths (15.9%) occurred, which included 76 adjudicated SCDs (3.4%) and 280 non-SCDs (12.5%). The SPRM showed acceptable discrimination [c-index = 0.63; 95% confidence interval (CI) 0.56-0.70], similar to that of original SPRM-derivation cohort. The calibration plot showed reasonable conformance. Among HF patients with reduced ejection fraction (EF; < 40%), SPRM showed improved discrimination compared with the ICD eligibility criteria (e.g. New York Heart Association functional Class II-III with EF ≤ 35%): c-index = 0.53 (95% CI 0.42-0.63) vs. 0.65 (95% CI 0.55-0.75) for SPRM. Finally, in the subgroup of 246 patients with both EF ≤ 35% and SPRM-predicted risk of ≥ 42.0% (SCD-HeFT defined ICD benefit threshold), mean ICD estimated HR was 0.70 (30% reduction of all-cause mortality by ICD). The cumulative incidence of SCD was 3.4% in Japanese HF registry. The SPRM performed reasonably well in Japanese patients and may aid in improving SCD prediction.

A STUDY OF IMPLANTABLE CARDIAC DEVICE ELIGIBILITY, UTILIZATION AND REASONS FOR NON-IMPLANTATION IN PATIENTS AT HEART FUNCTION CLINICS

Despite evidence and guideline recommendations, there is a presumptive underutilization of implantable cardioverter defibrillator (ICD) therapy in patients with heart failure (HF) even when seen by specialists. The primary aim of this study was to determine the rates of ICD eligibility and utilization among patients seen at heart function clinics (HFC). Secondary aims were to identify reasons for non-implantation among eligible patients and to determine predictors of non-implantation. As part of the EP Expert Working group of the Cardiovascular Strategic Clinical Network, we performed a retrospective review of consecutive patients seen at two HFCs in Alberta from 2013-2015. A detailed chart review was performed to collect demographics, clinical indications, comorbidities and to identify reasons for non-implantation. Eligibility for an ICD was determined using the 2008 ACC/AHA/HRS ICD guidelines and the 2013 CCS CRT guidelines. Patients were considered “guideline eligible” if they met the following criteria; left ventricular ejection fraction (LVEF) ≤0.35, New York Heart Association (NYHA) Class I-III and an absence of either revascularization within 3 months or acute myocardial infarction within 40 days of determined device eligibility. Logistic regression was used (odd ratio, OR and 95% CI) to identify predictors of device non-implantation. Overall, 1239 unique patients were seen in a HFC, the majority were male (66%), the median age was 70 (IQR 59-80) and the median LVEF was 0.4 (IQR 0.28-0.53) Over the follow-up period, 55% of patients were never eligible for device therapy based on LVEF and NYHA criteria. Yearly rates of eligibility ranged from 32-37% and yearly rates of device utilization among eligible patients ranged from 19-34% (Figure 1). When a reason for non-implantation was accounted for, yearly utilization rates increased to 36-50%. Among eligible patients, independent predictors of device non-implantation were age >75 years (OR 1.90, 1.29-2.82), LVEF ≤0.35 (OR 3.50, 1.98-6.17) and cancer (OR 2.22, 1.04-4.74). In nearly half of the cases (n=283, 46%), no clear documented reason for non-implantation was found. When a reason was documented, it was most commonly patient preference (25%), technical reasons (19%) and medical reasons (10%). We found that less than half of eligible patients received an ICD even when seen by specialists in a HFC and a reason for non-implant was often missing. Appropriate ICD utilization could be improved with initiatives aimed at screening high-risk individuals, along with requirements for documentation on reasons for non-eligibility.

A Population-Based Study of Adherence to Guideline Recommendations and Appropriate-Use Criteria for Implantable Cardioverter Defibrillators

Studies evaluating physician adherence to guideline recommendations for implantable cardioverter defibrillator (ICD) therapy are sparse, and none exist for the application of appropriate-use criteria (AUC) in clinical practice. As part of a quality improvement initiative, a review of all ICD procedures was performed from January 1, 2015 to December 31, 2016 in Alberta, Canada, to evaluate the proportion of patients receiving appropriate ICD therapy and to identify reasons for nonadherence. Our device-implant process involves an electrophysiologist or implanting cardiologist evaluation, reminders of ICD eligibility criteria on the device requisition, and peer-review consensus. Implants were classified according to the 2008 American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) ICD guidelines, 2013 Canadian Cardiovascular Society (CCS) Cardiac Resynchronization Therapy (CRT) guidelines, and 2013 AUC. There were 1,300 ICD procedures performed, and the mean age was 63.8 ± 12.9 years; 79% were male; the mean ejection fraction was 0.32 ± 0.13, and 69% were for primary prevention. Among all implants, < 1% were discordant with American College of Cardiology/American Heart Association/Heart Rhythm Society (ACC/AHA/HRS) recommendations. Among CRT implants, 10% were inconsistent with Canadian Cardiovascular Society (CCS) recommendations. According to AUC, 92% of implants were appropriate. Reasons for nonadherence to ACC/AHA/HRS recommendations included QRS width < 120 msec (n = 3), LVEF > 0.35 (n = 2) and recent myocardial infarction (MI) (n = 1). The most common reason for nonadherence to AUC was the absence of criteria for classification (n = 57, 4%). In this population-based study, we found that a process of specialist evaluation, eligibility reminders on device forms, and peer-review consensus may improve adherence to guideline recommendations and AUC for ICD therapy.

Clinical Impact of Cardiac Magnetic Resonance Imaging Versus Echocardiography-Guided Patient Selection for Primary Prevention Implantable Cardioverter Defibrillator Therapy

The main eligibility criterion for primary prevention implantable cardioverter defibrillator (ICD) therapy, that is, left ventricular ejection fraction (LVEF), is based on large clinical trials using primarily 2-dimensional echocardiography (2DE). Presently, cardiac magnetic resonance imaging (MRI) is considered the gold standard for LVEF assessment. It has been demonstrated that cardiac MRI assessment results in lower LVEFs compared with 2DE. Consequently, cardiac MRI-LVEF assessment may lead to more patients eligible for ICD implantation with potential clinical consequences. The aim of this study was to evaluate the clinical impact of cardiac MRI-LVEF versus 2DE-LVEF assessment for ICD eligibility. A total of 149 patients with cardiac MRI-LVEF ≤35% referred for primary prevention ICD implantation who underwent both 2DE and cardiac MRI-LVEF assessment were retrospectively included. 2DE-LVEF was computed by Simpson's biplane method. Cardiac MRI-LVEF was computed after outlining the endocardial contours in short-axis cine images. Appropriate device therapy (ADT) and all-cause mortality were evaluated during 2.9 ± 1.7years of follow-up. The present study found that cardiac MRI-LVEF was significantly lower compared with 2DE-LVEF (23 ± 8% vs 30 ± 8%, respectively, p <0.001), resulting in 29 (19%) more patients eligible for ICD implantation according to the current guidelines (LVEF ≤35%). Patients with 2DE-LVEF >35% but cardiac MRI-LVEF ≤35% experienced a lower ADT rate compared with patients having 2DE-LVEF ≤35% (2.1% vs 10.4% per year, respectively, p= 0.02). Application of cardiac MRI-LVEF cutoff of 30% resulted in 119 eligible patients experiencing 9.9% per year ADT, comparable with 2DE-LVEF cut-off value of 35%. In conclusion, cardiac MRI-LVEF assessment resulted in more patients eligible for ICD implantation compared with 2DE who showed a relatively low event rate during follow-up. The event rate in patients with cardiac MRI-LVEF ≤30% was comparable with patients having a 2DE-LVEF ≤35%. This study suggests the need for re-evaluation of cardiac MRI-based LVEF cut-off values for ICD eligibility.

Imaging to guide ICD therapy: beware what lies beneath.

Imaging to guide ICD therapy: beware what lies beneath.

How many patients fulfil the surface electrocardiogram criteria for subcutaneous implantable cardioverter-defibrillator implantation?

To determine the number of patients with a primary or secondary prevention implantable cardioverter-defibrillator (ICD) indication who are eligible for subcutaneous ICD (S-ICD) implantation according to the S-ICD manufacturer's surface electrocardiogram (ECG) screening template. One hundred and ninety-six ICD patients with a non-paced ventricle were assessed using erect and supine ECG limb lead recordings to simulate the three S-ICD sensing vectors. Each ECG lead was scrutinized by two independent observers. Subcutaneous ICD eligibility required two or more leads to satisfy the S-ICD screening template in both erect and supine positions. Overall, 85.2% of patients [95% confidence interval (CI): 80.2-90.2%] fulfilled surface ECG screening criteria. The proportion of patients with 3, 2, 1, and 0 qualifying leads were 37.2% (95% CI: 30.4-44.0%), 48.0% (95% CI: 41.0-55.0%), 11.2% (95% CI: 6.8-15.6%), and 3.6% (95% CI: 1.0-6.2%). The S-ICD screening template was satisfied more often by Lead III (primary vector, 83.7%, 95% CI: 78.5-88.9%) and Lead II (secondary vector, 82.7%, 95% CI: 77.4-88.0%) compared with Lead I (alternate vector, 52.6%, 95% CI: 45.6-59.6%). A prolonged QRS duration was the only baseline characteristic independently associated with ineligibility for S-ICD implantation. There was 92.9% agreement between the two independent observers in assessment of eligibility using the S-ICD screening template. About 85.2% of patients with an indication for a primary or secondary prevention ICD have a surface ECG that is suitable for S-ICD implantation when assessed with an S-ICD screening template. There is minor inter-observer variation in assessment of eligibility using the S-ICD screening template.

Clinical consequences of left ventricular ejection fraction assessment with cardiac magnetic resonance imaging in patients eligible for implantable cardioverter defibrillator therapy

Purpose: Eligibility for implantable cardioverter defibrillator (ICD) therapy for primary prevention primarily requires a left ventricular ejection fraction (LVEF) below 35% according to current guidelines. This criterion is based on large clinical trials using 2D-echocardiography (2DE) to assess LVEF. Presently, cardiac magnetic resonance imaging (CMR) is increasingly used for LVEF assessment and considered as gold standard. It is previously shown that 2DE significantly overestimates LVEF compared with CMR in patients with impaired LVEF. Consequently, CMR based LVEF assessment may result in an increase of patients eligible for ICD implantation. However, data on the consequences in clinical follow-up are lacking. The aim of this study was to evaluate the clinical consequences of CMR based LVEF assessment for device eligibility. Methods: Patients who were referred for ICD implantation for primary prevention based on CMR LVEF assessment according to current guidelines (LVEF≤35%) were retrospectively selected. Inclusion criteria were: LVEF assessment within 3 months prior to device implantation and 2DE-LVEF assessment within 3 months of CMR. 2DE-LVEF was computed by Simpson's biplane method. CMR-LVEF was computed after outlining of the endocardial contours in a stack of short-axis cine images. The occurrence of appropriate device therapy (ADT) was evaluated during a follow-up of 3 years after device implantation. Results: Seventy-three patients were included (49 male, mean age 64±10, 44 ischaemic CMP, 36 cardiac resynchronization therapy). 2DE significantly overestimated LVEF compared with CMR measurements (32±9% vs. 23±7%, respectively, p 35% (n=23) had a low incidence of ADT (1 event, 4%). When applying a CMR based LVEF cut-off of 30%, eligible patients (n=59) had 19% ADT, comparable with patients eligible based on 2DE-LVEF ≤35%. Conclusion: Our study indicates that CMR based LVEF assessment results in an increased number of patients eligible for ICD implantation. Patients eligible based on CMR but not 2DE had a low event rate in this study. This study suggests that CMR based LVEF cut-off values for ICD eligibility should be reevaluated.

Volumetric Left Ventricular Ejection Fraction is Superior to 2-Dimensional Echocardiography for Risk Stratification of Patients for Primary Prevention Implantable Cardioverter-Defibrillator Implantation

Current guidelines recommend an implantable cardioverter-defibrillator (ICD) according to the left ventricular ejection fraction (LVEF). However, they do not mandate volumetric LVEF assessment. We sought to determine whether volumetric LVEF measurement using cardiovascular magnetic resonance imaging (CMR-LVEF) is superior to conventional LVEF measurement using 2-dimensional transthoracic echocardiography (Echo-LVEF) for risk stratifying patients referred for primary prevention ICD. Patients who underwent primary prevention ICD implantation at our institution and had undergone preimplantation CMR-LVEF from November 2001 to February 2011 were identified. Volumetric CMR-LVEF was determined from cine short-axis data sets. CMR-LVEF and Echo-LVEF were extracted from the clinical reports. The end point was appropriate ICD discharge (shock and/or antitachycardia pacing). Of 48 patients, appropriate ICD discharge occurred in 9 (19%) within 29 ± 25 months (range 1 to 99, median 20). All patients met the Echo-LVEF criteria for ICD implantation; however 25% (95% confidence interval 13% to 37%) did not meet the CMR-LVEF criteria. None (0%) of these latter patients had received an appropriate ICD discharge. Using CMR-LVEF ≤30% as a threshold for ICD eligibility, 19 patients (40%) with a qualifying Echo-LVEF would not have been referred for ICD, and none (0%) received an ICD discharge.For primary prevention ICD implantation, volumetric CMR-LVEF might be superior to clinical Echo-LVEF for risk stratification and can identify a large minority of subjects in whom ICD implantation can be safely avoided. In conclusion, if confirmed by larger prospective series, volumetric methods such as CMR should be considered a superior "gatekeeper" for the identification of patients likely to benefit from primary prevention ICD implantation.

Prediction of Arrhythmic Events in Ischemic and Dilated Cardiomyopathy Patients Referred for Implantable Cardiac Defibrillator

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 &lt;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.

Impact of Cardiovascular Magnetic Resonance Assessment of Ejection Fraction on Eligibility for Cardioverter Defibrillator Implantation

Methods: Between September 2008 and August 2011 we prospectively analysed radiation dose and determinants in four cohorts of consecutive patients (n= 525) undergoing CCT at pre-defined time points – post-installation, post consoleupgrades andpost introductionof an iterative image reconstruction algorithm (AIDR3D). The impact of these updates on radiation dose were analysed by BMI subgroups (BMI≤ 20,20 35 had reduced median dose-length product from 1142.3mGy cm (IQR: 915–1759, n= 31) (1st cohort) to 318.4mGy cm (IQR: 254–515, n= 16) (4th cohort) (p< 0.001). All CCTs were of diagnostic quality. 503 Impact of Cardiovascular Magnetic Resonance Assessment of Ejection Fraction on Eligibility for Cardioverter Defibrillator Implantation S. Joshi 1,∗, K. Connelly 2, L. Jimenez-Juan3, M. Hansen4, P. Dorian2, A. Crean3, G. Wright 4, A. Yan2, H. Leong-Poi 2 1 Royal Melbourne Hospital, Australia 2 St Michael’s Hospital, University of Toronto, Canada 3 Toronto General Hospital, University of Toronto, Canada 4 Sunnybrook Health Sciences Centre, University of Toronto, Canada Background: For the primary prevention of sudden cardiac death, guidelines provide left ventricular ejection fraction (EF) criteria for implantable cardioverter defibrillator (ICD) placement. We sought to investigate the potential impact of performing cardiovascular magnetic resonance (CMR) for EF on ICD eligibility. Methods: Patients referred for consideration of ICD implantationunderwentCMR forEFmeasurementwithin 30 days of echocardiography. Echocardiographic EF was determined by Simpson’s biplane method and CMR EF was measured by Simpson’s summation of discs method. Results: Fifty-two patients (age 62± 15 years, 81%male) had a mean EF of 38± 14% by echocardiography and 35± 14% by CMR. CMR had greater reproducibility than Conclusion: Updates in image processing and acquisition have lead to substantial decreases in CCT radiation dose across all ranges of BMI. Progressive minimisation and knowledge of CCT radiation dose, particularly in the obese population, assists in the appropriate use of this non-invasive coronary imaging modality. http://dx.doi.org/10.1016/j.hlc.2012.05.513 echocardiography for both intra-observer (ICC, 0.98 vs 0.94) and inter-observer comparisons (ICC 0.99 vs 0.93). The limits of agreement comparing CMR and echocardiographic EF were −16 to +10 percentage points. CMR resulted in 11 of 52 (21%) and5of 52 (10%) of patients being reclassified regarding ICD eligibility at the EF thresholds of 35 and 30%, respectively. Among patients with an echocardiographic EF of between 25 and 40%, nine of 22 (41%) were reclassified by CMR at either the 35 or 30% threshold. Echocardiography identified only one of the six patients with left ventricular thrombus noted incidentally on CMR. Conclusions: CMR resulted in 21% of patients being reclassified regarding ICD eligibility when strict EF criteria were used. In addition, CMR detected unexpected left ventricular thrombus in almost 10% of patients. http://dx.doi.org/10.1016/j.hlc.2012.05.514

674 The potential clinical impact of cardiovascular magnetic resonance on eligibility for implantable cardioverter defibrillators

674 The potential clinical impact of cardiovascular magnetic resonance on eligibility for implantable cardioverter defibrillators

Extent of and Reasons for Nonuse of Implantable Cardioverter Defibrillator Devices in Clinical Practice Among Eligible Patients With Left Ventricular Systolic Dysfunction

Several studies that used claims and registry data have reported that 40% to 80% of patients eligible for an implantable cardioverter defibrillator (ICD) fail to receive one in clinical practice, and the rates are especially high among women and blacks. The extent and documented reasons for nonuse of ICDs among patients with left ventricular systolic dysfunction are unknown. Using hospital claims and clinical data, we identified patients hospitalized with a heart failure diagnosis and left ventricular ejection fraction ≤30% between January 1, 2007, and August 30, 2007, at a tertiary-care center. Using claims data, we determined placement of an ICD or cardiac resynchronization therapy with defibrillation device at any time up to 1 year after hospitalization. Medical records for patients without an ICD were abstracted to determine reasons for nonuse. Patients with an ICD were compared with patients without an ICD and also with patients without an ICD who did not have any contraindication for an ICD as identified through chart abstraction. Of the 542 potentially eligible patients identified, 224 (41%) did not have an ICD. In the initial adjusted analysis, female sex (odds ratio=1.90; 95% CI, 1.28 to 2.81) and increasing age (odds ratio=1.07; 95% CI, 1.04 to 1.11) were associated with a higher likelihood of not having an ICD. After detailed chart review, of the 224 patients without an ICD, 117 (52%) were ineligible for the device and 38 (17%) patients refused the device, resulting in only 69 (13%) patients eligible for an ICD who failed to receive one. In this subsequent adjusted analysis, remaining factors associated with a higher likelihood of not having an ICD were absence of ventricular arrhythmias (odds ratio=4.93; 95% CI, 2.56 to 9.50), noncardiology hospital service (odds ratio=3.73; 95% CI, 1.98 to 7.04), and lack of health insurance (odds ratio=3.10; 95% CI, 1.48 to 6.46). On the basis of a detailed chart review, the true rate of ICD underuse may be substantially lower than previous estimates. In addition, after accounting for ICD eligibility criteria, patient sex and age disparities in ICD therapy were no longer present.

Impact of cardiovascular magnetic resonance assessment of ejection fraction on eligibility for implantable cardioverter defibrillators

Methods The study population consisted of patients referred for LVEF measurement by CMR, for consideration of ICD implantation, who also underwent echocardiography within 30 days of the CMR. LVEF was assessed on echocardiography using Simpson’s biplane method. LVEF was determined from CMR based on manual planimetry of SSFP cine images of contiguous left ventricular short axis slices. CMR and echocardiography derived LVEFs were reported by two independent blinded observers.

The novel role of Micro T-Wave alternans in arrhythmic risk stratification of patients with left ventricular dysfunction

According to the recent class I recommendation of ACC/AHA guidelines, all patients with an ischemic and non-ischemic cardiomyopathy, New York Heart Association (NYHA) functional class II­III and left ventricular ejection fraction (LVEF) ≤ 30% could benefit from implantable cardioverter defibrillator (ICD) therapy for primary prevention of sudden cardiac death (SCD). Nevertheless, trials have highlighted a small absolute reduction in annual mortality from ICD therapy in this population. Moreover, costs of these devices would be excessive for medical care. For these reasons, it is nowadays mandatory to further identify in this big population a low arrhythmic risk subgroup of patients who is unlikely to benefit from ICD placement. On the other hand, by focusing only on LVEF ≤ 30% as risk predictor for SCD, there is the danger of missing a significant number of patients with LVEF beyond this value that might benefit from ICD therapy. In the last few years, several clinical studies have demonstrated that micro T-wave alternans (MTWA), a new stratifier for arrhythmic risk, is an effective tool to identify patients with LVEF ≤ 30% who are at low risk of SCD, and who are unlikely to require ICD therapy. Moreover, recent data have confirmed that MTWA is a promising stratifier for malignant arrhythmias in patients with LVEF ranging from 30 to 40%, so that this new non-invasive test could be useful also in this “borderline” population to identify high risk patients not meeting ICD eligibility criteria of current guidelines.