Article

Population-Based Analysis of Sudden Cardiac Death With and Without Left Ventricular Systolic Dysfunction

Heart Rhythm Research Laboratory, Division of Cardiology, Oregon Health and Science University, Portland, Oregon.
Journal of the American College of Cardiology (Impact Factor: 15.34). 03/2006; 47(6):1161-6. DOI: 10.1016/j.jacc.2005.11.045
Source: PubMed

ABSTRACT We sought to evaluate the contribution of left ventricular (LV) dysfunction toward occurrence of sudden cardiac death (SCD) in the general population, and to identify distinguishing characteristics of SCD in the absence of LV dysfunction.
Patients who manifest warning symptoms and signs are more likely to undergo evaluation before SCD. Although prevalence of LV dysfunction in this subgroup may overestimate the prevalence in overall SCD, this is the only means of assessment in the general population.
All cases of SCD in Multnomah County, Oregon (population 660,486; 2002 to 2004) were prospectively ascertained in the ongoing Oregon Sudden Unexpected Death Study. We retrospectively assessed LV ejection fraction (LVEF) among subjects who underwent evaluation of LV function before SCD (normal: > or =55%; mildly to moderately reduced: 36% to 54%; and severely reduced: < or =35%). Of a total of 714 SCD cases (annual incidence 54 per 100,000), LV function was assessed in 121 (17%).
The LVEF was severely reduced in 36 patients (30%), mildly to moderately reduced in 27 (22%), and normal in 58 (48%). Patients with normal LVEF were distinguishable by younger age (66 +/- 15 years vs. 74 +/- 10 years; p = 0.001), higher proportion of females (47% vs. 27%; p = 0.025), higher prevalence of seizure disorder (14% vs. 0%; p = 0.002), and lower prevalence of established coronary artery disease (50% vs. 81%; p < 0.001).
In this community-wide study, only one-third of the evaluated SCD cases had severe LV dysfunction meeting current criteria for prophylactic cardioverter-defibrillator implantation. The SCD cases with normal LV function had several distinguishing clinical characteristics. These findings support the aggressive development of alternative screening methods to enhance identification of patients at risk.

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    • "These malignant arrhythmias can be terminated by implantable cardioverter-defibrillator (ICD) therapy. Currently, poor left ventricular ejection fraction (LVEF) is the primary index that is used to decide whether or not to implant an ICD [1-6]. However, many patients with poor LVEF may not benefit from the ICD implantation as the annual firing rates are approximately 5% [1,5]. "
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    ABSTRACT: 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. 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. 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. 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.
    Journal of Cardiovascular Magnetic Resonance 06/2013; 15(1):57. DOI:10.1186/1532-429X-15-57 · 5.11 Impact Factor
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    • "Specifically, even when cardiac patients die suddenly at advanced stages of heart failure, the mode of SCD is frequently not due to sustained VAs but rather due to asystole or/and electromechanical disssociation, a clinical situation that ICD has little or nothing to offer [8]. On the contrary, at the early stages of heart failure, when most of the dying patients are SCD victims, the corresponding mode of SCD is due to the unpredictable occurrence of sustained VAs, a situation where the potential role of ICD is critical [9]. In these patients with preserved LVEF, an electrophysiological (EP) guided approach to select those high risk patients who may benefit from the ICD implantation may be crucial. "
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    ABSTRACT: BACKGROUND: Current guidelines for the primary prevention of sudden cardiac death have used a left ventricular ejection fraction (LVEF) ≤35% as a critical point to justify implantable cardioverter defibrillator (ICD) implantation in post myocardial infarction patients and in those with nonischemic dilated cardiomyopathy. We compared mortality and ICD activation rates among different ICD group recipients using a cut-off value for LVEF ≤35%. METHODS: We followed up for a mean period of 41.1months 495 ICD recipients (442 males, 65.6years old, 68.9% post myocardial infarction patients, 422 with LVEF≤35%). Prevention was considered primary in patients who fulfilled guidelines criteria or had inducible ventricular arrhythmia during programmed ventricular stimulation for patients with LVEF >35%. RESULTS: Over the course of the trial, 84 of 495 patients died; 69 experienced cardiac death (6 sudden) and 15 non cardiac death. ICD recipients with LVEF ≤35% compared to those with preserved LVEF (mean LVEF=43%) had a greater incidence of total mortality (18% vs. 11%, log rank p=0.028) and cardiac death (15.4% vs. 5.5%, log rank p=0.005). There was no difference in the incidence for appropriate device therapy between patients with LVEF ≤35% and those with LVEF >35% (56.9% vs. 65.8%, log rank p=0.93). In the multivariate analysis the presence of advanced New York Heart Association stage predicted both total mortality (HR=2.69, 95% CI 1.771-4.086) and cardiac death (HR=3.437, 95% CI 2.163-5.463). CONCLUSIONS: ICD therapy may protect heart failure patients at early stages from arrhythmic morbidity and mortality, based on an electrophysiology-guided risk stratification approach.
    International journal of cardiology 04/2012; 167(4). DOI:10.1016/j.ijcard.2012.04.005 · 6.18 Impact Factor
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    • "Earlier echocardiographic studies have observed that an EF of 40% serves as the threshold for identifying high-risk individuals (Bigger, Jr., 1984; Greenberg, 1984). However, EF has reduced sensitivity in predicting sudden death (Buxton, 2007; Stecker, 2006). Speckle based strain has shown to be a robust technique for assessment of LV function and a recent study has demonstrated that speckle tracking strain is superior to EF for assessment of myocardial function post-myocardial infarction (Gjesdal, 2008). "
    Cardiac Defibrillation - Prediction, Prevention and Management of Cardiovascular Arrhythmic Events, 11/2011; , ISBN: 978-953-307-692-8
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