Sudden coronary death. Frequency of active coronary lesions, inactive coronary lesions, and myocardial infarction

A novel, minimally invasive, segmental myocardial infarction with a clear healed infarct borderzone in rabbits

Ventricular arrhythmias in the setting of a healed myocardial infarction have been studied to a much lesser degree than acute and subacute infarction, due to the pericardial scarring, which results from the traditional open-chest techniques used for myocardial infarction (MI) induction. We sought to develop a segmental MI with low perioperative mortality in the rabbit that allows optimal visualization and therefore improved study of the infarction borderzone. Rabbits underwent MI using endovascular coil occlusion of the first obtuse marginal artery. Three weeks postprocedure, we evaluated our model by echocardiography and electrophysiology studies, optical mapping of isolated hearts, and histological studies. Seventeen rabbits underwent the protocol (12 MI and 5 sham) with a 92% survival to completion of the study (11 MI and 5 sham). MI rabbits demonstrated wall motion abnormalities on echocardiography while shams did not. At electrophysiological study, two MI rabbits had inducible ventricular tachycardia and one had inducible ventricular fibrillation. Isolated hearts demonstrated no pericardial scarring with a smooth, easily identifiable infarct borderzone. Optical mapping of the borderzone region showed successful mapping of peri-infarct reentry formation, with ventricular fibrillation inducible in 11 of 11 MI hearts and 1 of 5 sham hearts. We demonstrate successful high resolution mapping in the borderzone, showing delayed conduction in this region corresponding to late deflections in the QRS on ECG. We report the successful development of a minimally invasive MI via targeted coil delivery to the obtuse marginal artery with an exceptionally high rate of procedural survival and an arrhythmogenic phenotype. This model mimics human post-MI on echocardiography, gross pathology, histology, and electrophysiology.

Absence of circadian variation of acute coronary syndrome onset in chronic kidney disease patients

BACKGROUND

Several studies have reported on the circadian variation in acute coronary syndrome (ACS) onset. The influence of morning blood pressure surge, platelet aggregation and sympathetic activity is believed to cause this circadian variation. At the same time, a high frequency of ACS and sympathetic nerve hyperactivity has been reported in chronic kidney disease (CKD). Therefore, we investigated the relationship between CKD and the circadian variation in ACS.

METHODS

This study included 460 consecutive patients undergoing primary percutaneous coronary intervention for ACS between 2003 and 2009. Patients undergoing hemodialysis were excluded. The subjects were divided into two groups according to the value of estimated glomerular filtration rate (eGFR): CKD group [eGFR ≤ 60 ml/min/1.73 m2 by Modification of Diet in Renal Disease (MDRD) equation] and No CKD group (eGFR > 60 ml/min/1.73 m2 by MDRD equation). Clinical and angiographic characteristics, as well as the time distribution of ACS, were compared between the two groups.

RESULTS

There were no significant differences in clinical and angiographic characteristics between the two groups. A significant increase in morning coronary events was observed in the No CKD group. This increase was absent in the CKD group.

CONCLUSIONS

The existence of CKD affected the circadian variation associated with the more frequent ACS onset observed in the No CKD group patients. Probably, these data may suggest the cause of frequent cardiovascular events in CKD patients.

Comparison of role of early (less than six hours) to later (more than six hours) or no cardiac catheterization after resuscitation from out-of-hospital cardiac arrest

Despite reports of patients with resuscitated sudden cardiac arrest (rSCA) receiving acute cardiac catheterization, the efficacy of this strategy is largely unknown. We hypothesized that acute cardiac catheterization of patients with rSCA would improve survival to hospital discharge. A retrospective cohort of 240 patients with out-of-hospital rSCA caused by ventricular tachycardia or fibrillation was identified from 11 institutions in Seattle, Washington from 1999 through 2002. Patients were grouped into those receiving acute catheterization within 6 hours (≤6-hour group, n = 61) and those with deferred catheterization at >6 hours or no catheterization during the index hospitalization (>6-hour group, n = 179). Attention was directed to survival to hospital discharge, neurologic status, extent of coronary artery disease, presenting electrocardiographic findings, and symptoms before arrest. Propensity-score methods were used to adjust for the likelihood of receiving acute catheterization. Survival was greater in patients who underwent acute catheterization (72% in the ≤6-hour group vs 49% in the >6-hour group, p = 0.001). Percutaneous coronary intervention was performed in 38 of 61 patients (62%) in the ≤6-hour group and 13 of 170 patients (7%) in the >6-hour group (p <0.0001). Neurologic status was similar in the 2 groups. A significantly larger percentage of patients in the acute catheterization group had symptoms before cardiac arrest and had ST-segment elevation on electrocardiogram after resuscitation. Age, bystander cardiopulmonary resuscitation, daytime presentation, history of percutaneous coronary intervention or stroke, and acute ST-segment elevation were positively associated with receiving cardiac catheterization. In conclusion, in this series of patients who sustained out-of-hospital cardiac arrest, acute catheterization (<6 hours of presentation) was associated with improved survival.

Characteristics of sudden arrhythmic death in a diverse, urban community

BACKGROUND

Sudden cardiac death (SCD) remains a major public health problem; however, its true burden remains unknown with widely variable estimates of its incidence. We aimed to examine the contemporary epidemiology and autopsy characteristics of SCD in an ethnically diverse community.

METHODS

Three physicians reviewed all deaths of individuals aged ≥20 years reported to the San Francisco medical examiner in 2007 for presentations fitting World Health Organization (WHO) SCD criteria-within 1 hour of symptom onset (witnessed) or within 24 hours of being observed alive and symptom free (unwitnessed). After comprehensive review of medical examiner investigation, WHO SCDs were classified as sudden arrhythmic death (SAD) or nonarrhythmic death. Coronary artery disease (CAD) and cardiac mass were evaluated in all SADs undergoing autopsy and compared with demographically similar accidental trauma control deaths.

RESULTS

We identified 252 WHO SCDs; 145 were SADs. Men had a 2.2-fold higher SAD rate (P < .0005). Blacks had a 3.15-fold higher SAD rate compared with whites (P = .003). Significant CAD was present in 38.9% of SADs and associated with higher SAD risk compared with control deaths (OR 2.58, 95% CI 1.12-5.97, P = .026). Mean cardiac mass was linearly associated with risk for SAD in cases without significant CAD (OR 2.06 per 100 g, 95% CI 1.43-2.98, P < .0005).

CONCLUSIONS

In a diverse, urban population, SAD incidence varied substantially by gender and race. Significant CAD accounted for far fewer SADs than previous studies but remained associated with a 2.6-fold higher risk as compared with control deaths. These findings may reflect the evolving contemporary epidemiology of SCD.

"Go with the flow": how Krüppel-like factor 2 regulates the vasoprotective effects of shear stress

Laminar shear stress is known to confer potent anti-inflammatory, antithrombotic, and antiadhesive effects by differentially regulating endothelial gene expression. The identification of Krüppel-like factor 2 as a flow-responsive molecule has greatly advanced our understanding of molecular mechanisms governing vascular homeostasis. This review summarizes the current understanding of Krüppel-like factor 2 action in endothelial gene expression and function.

Angioscopic and virtual histology intravascular ultrasound characteristics of culprit lesion morphology underlying coronary artery thrombosis

Although rupture of vulnerable plaque with subsequent thrombosis is the most common mechanism of acute coronary syndromes, a significant percentage of patients with acute coronary syndrome may not have plaque rupture. We used angioscopy and virtual histology intravascular ultrasound (VH-IVUS) to investigate the underlying morphology of coronary thrombosis. We correlated the angioscopic diagnosis of coronary thrombosis in 42 lesions (37 patients) with gray-scale and VH-IVUS findings of the underlying plaque. By angioscopy plaque rupture was present in 19 thrombotic lesions (45.2%), whereas 23 (54.8%) had no rupture. VH-IVUS findings comparing thrombotic lesions with to those without angioscopic plaque rupture were remarkably similar except that angioscopic nonruptures tended to have more necrotic core (NC) at the minimum lumen area site (22.2 ± 12.5% vs 16.3 ± 9.3%, p=0.09) and at the maximum NC site (32.7 ± 12.8% vs 25.0 ± 12.1%, p=0.053) compared to angioscopic ruptures. Furthermore, among 19 lesions with angioscopic plaque rupture, there were 11 VH thin-cap fibroatheromas (TCFAs; 57.9%); among 23 lesions without angioscopic rupture, there were 17 VH-TCFAs (73.9%, p=0.22). In conclusion, the similarity of VH-IVUS plaque composition (percentage of NC and percentage of VH-TCFA) in lesions with or without angioscopic plaque rupture suggest a spectrum of underlying morphologies to explain thrombosis in the absence of a ruptured plaque including classic erosions, small (and undetectable) plaque ruptures, and potentially unruptured TCFAs with superimposed thrombosis.

Women have less severe and extensive coronary atherosclerosis in fatal cases of ischemic heart disease: an autopsy study

OBJECTIVE

The study aims to evaluate sex differences in extent and severity of coronary artery disease (CAD) and myocardial findings at autopsy among young people with fatal ischemic heart disease (IHD).

BACKGROUND

Women with acute coronary syndrome are less likely than men to display obstructive CAD at angiography. This suggests unique mechanisms of acute coronary syndrome exist in women or may reflect prehospital death of women with the most severe CAD.

METHODS

Reports of autopsies by the Office of the Chief Medical Examiner of New York City on people aged 21 to 54 years who died between January 1, 2006, and December 31, 2008, were reviewed. A total of 639 cases of death due to atherosclerotic or arteriosclerotic cardiovascular disease according to the medical examiner were analyzed. Significant CAD was defined as ≥75% cross-sectional area stenosis in an epicardial vessel or ≥50% left main.

RESULTS

Women were less likely to have obstructive CAD (63% vs 77% of men, P = .002). There was pathologic evidence of myocardial infarction (MI) in 43% of cases, 17% of which had nonobstructive CAD. Frequency of MI did not vary by sex overall (38% of women vs 45% of men, P = .18) or among those without significant CAD (23% vs 29%, P = .45).

CONCLUSIONS

Among young people determined at autopsy to have died of IHD, fewer women had obstructive CAD, consistent with angiographic data in other IHD syndromes. Pathologic evidence of MI may exist in the absence of obstructive CAD.

Morphology of coronary artery lesions assessed by virtual histology intravascular ultrasound tissue characterization and fractional flow reserve

Fractional flow reserve (FFR) is an index of the physiological significance of a coronary stenosis. Patients who have lesions with a FFR of >0.80, even optimally treated with medication, have however a MACE rate ranging from 8 to 21%. Coronary plaques at high risk of rupture and clinical events can be also identified by virtual histology intravascular ultrasound (IVUS-VH) as plaques with high amount of necrotic core (NC) abutting the lumen. Aim of this exploratory study was to investigate whether the geometry and composition of lesions with FFR ≤ 0.80 were different from their counterparts. Fifty-five consecutive patients in whom FFR was clinically indicated on a moderate angiographic lesion, received also an imaging investigation on the same lesion with IVUS-VH. Data on plaque geometry and composition was analyzed. Patients were subdivided in two groups according to the value of FFR (> or ≤0.80). Lesions with a FFR ≤ 0.80 (n = 17) showed a slightly larger plaque burden than those with FFR > 0.80 (n = 38) (54.6 ± 0.7% vs. 51.7 ± 0.7% P = 0.1). In addition, they tend to have less content of necrotic core than their counterparts (14.2 ± 8% vs. 19.2 ± 10.2%, P = 0.08). No difference was found in the distribution of NC-rich plaques (fibroatheroma and thin-capped fibroatheroma) between groups (82% in FFR ≤ 0.80 vs. 79% in FFR > 0.80, P = 0.5). Although FFR ≤ 0.80 lesions have larger plaque size, they do not differ in composition from the ones with FFR > 0.80. Further exploration in a large prospective study is needed to study whether the lesions with FFR > 0.80 that are NC rich are the ones associated with the presence of clinical events at follow-up.

Development of an interactive model of the burden of future coronary heart disease from an employer perspective

OBJECTIVE

To create a computer-based model for employers to better understand the burden of coronary heart disease (CHD) to their organizations.

METHODS

A user-friendly model was developed to allow employers to evaluate the burden of CHD. Inputs include the demographic distribution by age and sex, prevalence of CHD and CHD risk factors, direct and indirect medical costs of CHD events, and discount and inflation rates. The model contains prediction equations derived from National Health and Nutrition Examination Survey data and Framingham Heart Study equations, used with employer inputs to predict future CHD events and expenditures.

RESULTS

Interactive graphs are presented for the employer's covered population alongside regional benchmarks. The time horizon and population may be adjusted.

CONCLUSIONS

This interactive model illustrates how pragmatic outcomes research can be converted into a transparent model addressing health care budget issues that is readily understood by corporate managers.

Carotid atherosclerosis does not predict coronary, vertebral, or aortic atherosclerosis in patients with acute stroke symptoms

BACKGROUND AND PURPOSE

The purpose of this study was to determine whether significant atherosclerotic disease in the carotid arteries predicts significant atherosclerotic disease in the coronary arteries, vertebral arteries, or aorta in patients with symptoms of acute ischemic stroke.

METHODS

Atherosclerotic disease was imaged using CT angiography in a prospective study of 120 consecutive patients undergoing emergent CT evaluation for symptoms of stroke. Using a comprehensive CT angiography protocol that captured the carotid arteries, coronary arteries, vertebral arteries, and aorta, we evaluated these arteries for the presence and severity of atherosclerotic disease. Significant atherosclerotic disease was defined as >50% stenosis in the carotid, coronary, and vertebral arteries, or >or=4 mm thickness and encroaching in the aorta. Presence of any and significant atherosclerotic disease was compared in the different types of arteries assessed.

RESULTS

Of these 120 patients, 79 had CT angiography examinations of adequate image quality and were evaluated in this study. Of these 79 patients, 33 had significant atherosclerotic disease. In 26 of these 33 patients (79%), significant disease was isolated to 1 type of artery, most often to the coronary arteries (N=14; 54%). Nonsignificant atherosclerotic disease was more systemic and involved multiple arteries.

CONCLUSIONS

Significant atherosclerotic disease in the carotid arteries does not predict significant atherosclerotic disease in the coronary arteries, vertebral arteries, or aorta in patients with symptoms of acute ischemic stroke. Significant atherosclerotic disease is most often isolated to 1 type of artery in these patients, whereas nonsignificant atherosclerotic disease tends to be more systemic.

Coronary artery disease, coronary revascularization, and outcomes in chronic advanced systolic heart failure

BACKGROUND

Associations between coronary artery disease (CAD) and outcomes in systolic heart failure (HF) and that between coronary artery bypass graft (CABG) surgery and outcomes in patients with HF and CAD have not been examined using propensity-matched designs.

METHODS

Of the 2707 patients with advanced chronic systolic HF in the Beta-Blocker Evaluation of Survival Trial (BEST), 1593 had a history of CAD, of whom 782 had prior CABG. Using propensity scores for CAD we assembled a cohort of 458 pairs of CAD and no-CAD patients. Propensity scores for prior CABG in those with CAD were used to assemble 500 pairs of patients with and without CABG. Matched patients were balanced on 68 baseline characteristics.

RESULTS

All-cause mortality occurred in 33% and 24% of matched patients with and without CAD respectively, during 26 months of median follow-up (hazard ratio {HR} when CAD was compared with no-CAD, 1.41; 95% confidence interval {CI}, 1.11-1.81; P=0.006). HR's (95% CIs) for CAD-associated cardiovascular mortality, HF mortality, and sudden cardiac death (SCD) were 1.53 (1.17-2.00; P=0.002), 1.44 (0.92-2.25; P=0.114) and 1.76 (1.21-2.57; P=0.003) respectively. CAD had no association with hospitalization. Among matched patients with HF and CAD, all-cause mortality occurred in 32% and 39% of those with and without prior CABG respectively (HR for CABG, 0.77; 95% CI, 0.62-0.95; P=0.015).

CONCLUSIONS

In patients with advanced chronic systolic HF, CAD is associated with increased mortality, and in those with CAD, prior CABG seems to be associated with reduced all-cause mortality but not SCD.

Sudden cardiac death: epidemiology and risk factors

Sudden cardiac death (SCD) is an important public-health problem with multiple etiologies, risk factors, and changing temporal trends. Substantial progress has been made over the past few decades in identifying markers that confer increased SCD risk at the population level. However, the quest for predicting the high-risk individual who could be a candidate for an implantable cardioverter-defibrillator, or other therapy, continues. In this article, we review the incidence, temporal trends, and triggers of SCD, and its demographic, clinical, and genetic risk factors. We also discuss the available evidence supporting the use of public-access defibrillators.

Etiology of sudden death in the community: results of anatomical, metabolic, and genetic evaluation

BACKGROUND

Identifying persons at risk for sudden cardiac death (SCD) is challenging. A comprehensive evaluation may reveal clues about the clinical, anatomical, genetic, and metabolic risk factors for SCD.

METHODS

Seventy-one patients who had SCD (25-60 years old) without an initially apparent cause of death were evaluated at the Hennepin County Medical Examiner's office (Minneapolis, MN) from August 2001 to July 2004. We reviewed their clinic records conducted next-of-kin interviews and performed autopsy, laboratory testing, and genetic analysis for mutations in genes associated with the long QT syndrome.

RESULTS

Mean age was 49.5 +/- 7 years, 86% were male, and 2 subjects had history of coronary heart disease (CHD). Coronary risk factors were highly prevalent in comparison to individuals of the same age group in this community (eg, smoking 61%, hypertension 27%, hyperlipidemia 25%) but inadequately treated. On autopsy, 80% of the subjects had high-grade coronary stenoses. Acute coronary lesions and previous silent myocardial infarction (MI) were found in 27% and 34%, respectively. Furthermore, 32% of the subjects had recently smoked cigarettes, and 50% had ingested analgesics. Possible deleterious mutations of the ion channel genes were detected in 5 subjects (7%). Of these, 4 were in the sodium channel gene SCN5A.

CONCLUSIONS

Most of the persons who had SCD in the community had severe subclinical CHD, including undetected previous MI. Traditional coronary risk factors were prevalent and undertreated. Mutations in the long QT syndrome genes were detected in a few subjects. These findings imply that improvements in the detection and treatment of subclinical CHD in the community are needed to prevent SCD.

Iodinated contrast opacification gradients in normal coronary arteries imaged with prospectively ECG-gated single heart beat 320-detector row computed tomography

BACKGROUND

To define and evaluate coronary contrast opacification gradients using prospectively ECG-gated single heart beat 320-detector row coronary angiography (CTA).

METHODS AND RESULTS

Thirty-six patients with normal coronary arteries determined by 320 x 0.5-mm detector row coronary CTA were retrospectively evaluated with customized image postprocessing software to measure Hounsfield Units at 1-mm intervals orthogonal to the artery center line. Linear regression determined correlation between mean Hounsfield Units and distance from the coronary ostium (regression slope defined as the distance gradient G(d)), lumen cross-sectional area (G(a)), and lumen short-axis diameter (G(s)). For each gradient, differences between the 3 coronary arteries were analyzed with ANOVA. Linear regression determined correlations between measured gradients, heart rate, body mass index, and cardiac phase. To determine feasibility in lesions, all 3 gradients were evaluated in 22 consecutive patients with left anterior descending artery lesions > or =50% stenosis. For all 3 coronary arteries in all patients, the gradients G(a) and G(s) were significantly different from zero (P<0.0001), highly linear (Pearson r values, 0.77 to 0.84), and had no significant difference between the left anterior descending, left circumflex, and right coronary arteries (P>0.503). The distance gradient G(d) demonstrated nonlinearities in a small number of vessels and was significantly smaller in the right coronary artery when compared with the left coronary system (P<0.001). Gradient variations between cardiac phases, heart rates, body mass index, and readers were low. Gradients in patients with lesions were significantly different (P<0.021) than in patients considered normal by CTA.

CONCLUSIONS

Measurement of contrast opacification gradients from temporally uniform coronary CTA demonstrates feasibility and reproducibility in patients with normal coronary arteries. For all patients, the gradients defined with respect to the coronary lumen cross-sectional area and short-axis diameters are highly linear, not significantly influenced by the coronary artery (left anterior descending artery versus left circumflex versus right coronary artery), and have only small variation with respect to patient parameters. Preliminary evaluation of gradients across coronary artery lesions is promising but requires additional study.

Morphologic characteristic of coronary artery disease, with emphasis on thromboses, in patients younger than 40 years of age

There are few pathologic descriptions of fatal coronary artery disease in the young. The morphologic characteristics of sudden coronary deaths in 47 hearts from patients younger than 40 years were studied. Numbers of plaques with necrotic cores were quantitated in each heart. Compared to 194 sudden coronary deaths >40 years, heart weight was lower, acute plaque erosions more frequent, and extent of disease less in the ≤40 years group. Plaque burden was less in hearts with erosions, and healed infarcts more common in hearts with stable plaque. The numbers of fibroatheromas increased with age until the 6th decade (P < .0001) as well as the proportion of total plaques that were atheromatous. Plaques in younger patients have fewer lipid-rich cores. Most thrombi show areas of organization, with layering frequent in erosions, suggesting a possible method of plaque enlargement in the absence of necrotic core formation.

Relationship of thrombus healing to underlying plaque morphology in sudden coronary death

OBJECTIVES

The aim of this study was to assess differences in thrombus healing between ruptured and eroded plaques, given the natural difference in lesion substrate and that thrombi might exist days to weeks before the presentation of sudden coronary death.

BACKGROUND

Although the ability to distinguish ruptures and erosions remains a major clinical challenge, in-hospital patients dying with acute myocardial infarction establish that erosions account for 25% of all deaths, where women experience a higher incidence compared with men.

METHODS

Coronary lesions with thrombi (ruptures, n = 65; erosions, n = 50) received in consultation from the Medical Examiner's Office from 111 sudden death victims were studied. Thrombus healing was classified as early (<1 day) or late stage characterized in phases of lytic (1 to 3 days), infiltrating (4 to 7 days), or healing (>7 days). Morphometric analysis included vessel dimensions, necrotic core size, and macrophage density.

RESULTS

Late-stage thrombi were identified in 79 of 115 (69%) culprit plaques. Women more frequently had erosion with a greater prevalence of late-stage thrombi (44 of 50, 88%) than ruptures (35 of 65, 54%, p < 0.0001). The internal elastic lamina area and percent stenosis were significantly smaller in erosions compared with ruptures (p < 0.0001 and p = 0.02), where plaque burden was greater (p = 0.008). Although macrophage infiltration in erosions was significantly less than ruptures (p = 0.03), there was no established relationship with thrombus organization. Other parameters of thrombus length and occlusive versus nonocclusive showed no association with healing.

CONCLUSIONS

Approximately two-thirds of coronary thrombi in sudden coronary deaths are organizing, particularly in young individuals-especially women, who perhaps might require a different strategy of treatment.

Sex differences in mortality following acute coronary syndromes

CONTEXT

Conflicting information exists about whether sex differences modulate short-term mortality following acute coronary syndromes (ACS).

OBJECTIVES

To investigate the relationship between sex and 30-day mortality in ACS, and to determine whether this relationship was modified by clinical syndrome or coronary anatomy using a large database across the spectrum of ACS and adjusting for potentially confounding clinical covariates.

DESIGN, SETTING, AND PARTICIPANTS

A convenience sample of patients pooled from 11 independent, international, randomized ACS clinical trials between 1993 and 2006 whose databases are maintained at the Duke Clinical Research Institute, Durham, North Carolina. Of 136 247 patients, 38 048 (28%) were women; 102 004 (26% women) with ST-segment elevation myocardial infarction (STEMI), 14 466 (29% women) with non-STEMI (NSTEMI), and 19 777 (40% women) with unstable angina.

MAIN OUTCOME MEASURE

Thirty-day mortality following ACS.

RESULTS

Thirty-day mortality was 9.6% in women and 5.3% in men (odds ratio [OR], 1.91; 95% confidence interval [CI], 1.83-2.00). After multivariable adjustment, mortality was not significantly different between women and men (adjusted OR, 1.06; 95% CI, 0.99-1.15). A significant sex by type of ACS interaction was demonstrated (P < .001). In STEMI, 30-day mortality was higher among women (adjusted OR, 1.15; 95% CI, 1.06-1.24), whereas in NSTEMI (adjusted OR, 0.77; 95% CI, 0.63-0.95) and unstable angina, mortality was lower among women (adjusted OR, 0.55; 95% CI, 0.43-0.70). In a cohort of 35 128 patients with angiographic data, women more often had nonobstructive (15% vs 8%) and less often had 2-vessel (25% vs 28%) and 3-vessel (23% vs 26%) coronary disease, regardless of ACS type. After additional adjustment for angiographic disease severity, 30-day mortality among women was not significantly different than men, regardless of ACS type. The relationship between sex and 30-day mortality was similar across the levels of angiographic disease severity (P for interaction = .70).

CONCLUSIONS

Sex-based differences existed in 30-day mortality among patients with ACS and vary depending on clinical presentation. However, these differences appear to be largely explained by clinical differences at presentation and severity of angiographically documented disease.

Decreased frequency of the 3'UTR T>G single nucleotide polymorphism of thrombospondin-2 gene in sudden death due to plaque erosion

OBJECTIVE

Clinical studies have suggested a potentially "protective" variant of the thrombospondin gene 2 (THBS2, MIM*188061). Autopsy studies investigating the frequency of THBS2 polymorphisms in different coronary substrates have not been done.

METHODS

We evaluated the frequency of the T>G THBS2 (SNP ID G5755e5) polymorphism in 439 cases of sudden unexpected death, including acute thrombosis occurring on plaque erosion (n=60), acute thrombosis occurring on plaque rupture (n=54), severe coronary artery disease without acute thrombus (n=76), and 249 sudden unexpected deaths without significant coronary disease. Allele types were determined by polymerase chain reaction of DNA extracted from autopsy frozen tissues.

RESULTS

In controls, there were 60.2% wild-type, 35.3 % TG, and 4.4% GG phenotypes. The frequency of G allele carriers (TG or GG) was 23.3% in erosions vs. 39.8% in controls (P=.02). There was no difference in controls vs. plaque ruptures (40.7%) or severe CAD without thrombus (38.2%). By multivariate analysis, lack of G allele (wild-type TT genotype) was associated with plaque erosion [odds ratio (OR) 2.2, P=.02], independent of age, gender, and cigarette smoking. When combined with a history of cigarette smoking, the association between TT genotype and plaque erosion was greater (OR 3.5, P < or = .0001).

CONCLUSION

The T>G THBS2 is decreased only in plaque erosion, with no difference in frequency between other coronary disease and controls.

Monocytes and neutrophils expressing myeloperoxidase occur in fibrous caps and thrombi in unstable coronary plaques

Background

Myeloperoxidase (MPO) -containing macrophages and neutrophils have been described at sites of plaque rupture. The presence of these cells in precursor lesions to acute rupture (thin cap atheroma, or vulnerable plaque) and within thrombi adjacent to ruptures has not been described, nor an association with iron-containing macrophages within unstable plaques.

Methods

We studied 61 acute ruptures, 15 organizing ruptures, 31 thin cap fibroatheromas, and 28 fibroatheromas from 72 sudden coronary death victims by immunohistochemical and histochemical techniques. Inflammatory cells were typed with anti-CD68 (macrophages), anti-BP-30 (neutrophil bactericidal glycoprotein), and anti-MPO. Iron was localized by Mallory's Prussian blue stain. In selected plaques alpha smooth muscle actin (DAKO, Carpinteria, CA, clone M0851) was performed.

Results

MPO positive cells were present in 79% of ruptured caps, 28% of thin cap fibroatheroma, and no fibroatheromas; neutrophils were present in 72% of ruptures, 8% of thin cap fibroatheromas, and no fibroatheromas. Iron containing foam cells were present in the caps of 93% of acute ruptures, of 85% of organizing ruptures, 20% of thin cap atheromas, and 10% of fibroatheromas. MPO positive cells were more frequent in occlusive than non-occlusive thrombi adjacent to ruptures (p = .006) and were more numerous in diabetics compared to non-diabetics (p = .002)

Conclusion

Unstable fibrous caps are more likely to contain MPO-positive cells, neutrophils, and iron-containing macrophages than fibrous caps of stable fibroatheromas. MPO-positive cells in thrombi adjacent to disrupted plaques are associated with occlusive thrombi and are more numerous in diabetic patients.

Mechanical stress analysis of a rigid inclusion in distensible material: a model of atherosclerotic calcification and plaque vulnerability

The role of atherosclerotic calcification in plaque rupture remains controversial. In previous analyses using finite element model analysis, circumferential stress was reduced by the inclusion of a calcium deposit in a representative human anatomical configuration. However, a recent report, also using finite element analysis, suggests that microscopic calcium deposits increase plaque stress. We used mathematical models to predict the effects of rigid and liquid inclusions (modeling a calcium deposit and a lipid necrotic core, respectively) in a distensible material (artery wall) on mechanical failure under uniaxial and biaxial loading in a range of configurations. Without inclusions, stress levels were low and uniform. In the analytical model, peak stresses were elevated at the edges of a rigid inclusion. In the finite element model, peak stresses were elevated at the edges of both inclusions, with minimal sensitivity to the wall distensibility and the size and shape of the inclusion. Presence of both a rigid and a soft inclusion enlarged the region of increased wall stress compared with either alone. In some configurations, the rigid inclusion reduced peak stress at the edge of the soft inclusion but simultaneously increased peak stress at the edge of the rigid inclusion and increased the size of the region affected. These findings suggest that the presence of a calcium deposit creates local increases in failure stress, and, depending on relative position to any neighboring lipid pools, it may increase peak stress and the plaque area at risk of mechanical failure.

Coronary CT angiography (CCTA) and advances in CT plaque imaging

The goal of this review is to highlight current advances in the non-invasive detection of clinically significant atherosclerotic disease including the so-called vulnerable plaque with computed tomography. Atherosclerotic disease encompasses stages of plaque progression, stabilization, and even regression. Traditionally, the focus of diagnostic imaging has been the detection of lumen-occluding atheroma. However, advances in our understanding of the pathophysiology of atherosclerotic plaque have shown that, in certain stages of plaque progression, plaque is "vulnerable" and able to cause acute coronary syndromes despite "non-significant" vascular occlusion at baseline. This provides a rationale to improve our non-invasive imaging technology. Presented here are improvements in soft-tissue resolution with technical advancements as well as contrast-enhancement and lately even nanotechnology-based technology which are geared to detect the clinically elusive vulnerable plaque and provide an opportunity for preventative therapy.

Silent myocardial ischemia

Although much progress has been made in reducing mortality from ischemic cardiovascular disease, this condition remains the leading cause of death throughout the world. This might in part be due to the fact that over half of patients have a catastrophic event (heart attack or sudden death) as their initial manifestation of coronary disease. Contributing to this statistic is the observation that the majority of myocardial ischemic episodes are silent, indicating an inability or failure to sense ischemic damage or stress on the heart. This review examines the clinical characteristics of silent myocardial ischemia, and explores mechanisms involved in the generation of angina pectoris. Possible mechanisms for the more common manifestation of injurious reductions in coronary flow; namely, silent ischemia, are also explored. A new theory for the mechanism of silent ischemia is proposed. Finally, the prognostic importance of silent ischemia and potential future directions for research are discussed.

Atheromatous plaque reflects serum total cholesterol levels: a comparative morphologic study of endarterectomy coronary atherosclerotic plaques removed from patients from the southern part of India and Caucasians from Ottawa, Canada

BACKGROUND

Natives of South India have a very high incidence of coronary artery disease, despite low calorie and fat intake.

HYPOTHESIS

This study was undertaken to determine whether morphologic features of atheromatous plaque reflect the serum total cholesterol.

METHODS

Fifty-three endarterectomy specimens from patients (mean age 47 +/- 9 years, mean cholesterol 203 +/- 47 mg/dl) obtained from one cardiac surgeon working in a single institution in South India were evaluated. Morphologic findings were compared with 40 endoarterectomy specimens obtained from age-matched Caucasians from Ottawa, Canada, with a reported mean cholesterol of 262 +/- 47 mg/dl. Morphometric measurements of the vessel size, percent stenosis, and the various components of the atherosclerotic plaque were determined by computerized planimetry.

RESULTS

The vessel size was smaller in the Indian than in the Canadian population (4.6 +/- 2.9 vs. 5.6 +/- 3.0 mm2, p = 0.07), the plaque area was less (4.3 +/- 2.3 vs. 5.3 +/- 2.8 mm2, p = 0.055) and the calculated percent stenosis was significantly less (93 vs. 96%, p = 0.028). Of all the parameters evaluated, only necrotic core in the Indian population (7.1 +/- 10.9% vs. Canadian 16.7 +/- 19.7%, p < 0.001) and proteoglycan deposition (7.9 +/- 11.2% vs. Canadian 3.7 +/- 5.3%, p < 0.023) were significantly different. Despite the Indians having low total cholesterol, there was greater diffuse double and triple-vessel disease and at a younger age than in the Caucasians.

CONCLUSIONS

From our data, it appears that the mechanism of development of atherosclerotic disease in the Indians may be different because they have smaller vessels, smaller necrotic core, and greater proteoglycan deposition. Other etiologies, especially those related to a high carbohydrate diet (which is typical for South Indians), should be considered.

Angiographic and clinical implications of combined ST-segment elevation in anterior and inferior leads in acute myocardial infarction

BACKGROUND

The clinical and angiographic findings of patients suffered from acute myocardial infarction (MI) and presented with combined ST elevation in both anterior and inferior leads remain unclear.

HYPOTHESIS

These patients might have >/= 1 coronary arteries occluded.

METHODS

From January 2002 to December 2006, 49 consecutive patients were found to have ST elevation in both anterior and inferior leads during myocardial infarction. Patients who had left circumflex artery occlusion (acute or chronic) were excluded. These patients were divided into 4 types according to the infarct-related artery (IRA) and status of the contralateral vessel patency: left anterior descending artery (LAD) as the IRA with a patent right coronary artery (RCA) (type 1A, n = 25); LAD as IRA with an occluded RCA (type 1B, n = 1); RCA as IRA with a patent LAD (type 2A, n = 19); and RCA as IRA with an occluded LAD (type 2B, n = 4).

RESULTS

Single vessel occlusion (type A angiographic pattern) was found in 90% of patients. Type 1A patients had a larger infarct size than that of 2A. ST elevation in V(2) >/= V(3) identified RCA as the IRA with a high specificity (92%) and sensitivity (74%). Type 2B patients (2-vessel occlusion) had a larger infarct size than that of 2A; however, no electrocardiogram (ECG) criteria could reliably differentiate them.

CONCLUSION

In a real world situation, single vessel occlusion is found in the majority of cases of combined ST elevation in anterior and inferior leads. ST elevation in V(2) >/= V(3) distinguishes RCA against LAD as the IRA with high accuracy.

Comparison of risk profiles between survivors and victims of sudden cardiac death from an acute coronary event

AIM

This study was designed to compare the risk profiles of sudden cardiac death (SCD) victims and survivors of an acute coronary event.

METHOD

A case-control study included consecutive victims of SCD (n=425) verified to be due to an acute coronary event at medicolegal autopsy and consecutive patients surviving an acute myocardial infarction (AMI) (n=644).

RESULTS

Family history of SCD (odds ratio (OR) 1.5, 95% confidence interval (CI) 1.0-2.2, P=0.03), male gender (OR 1.8, 95% CI 1.3-2.4, P<0.001), current smoking (OR 2.0, 95% CI 1.5-2.6, P<0.001), cardiac hypertrophy (OR 3.0, 95% CI 2.3-3.9, P<0.001) and three-vessel coronary artery disease (CAD) (OR 5.4, 95% CI 3.6-8.2, P<0.001) were more common among the victims of SCD as compared to survivors of AMI. There was a cumulative increase of risk of being a SCD victim versus AMI survivor when more than one risk factor was present, with the OR rising to 44.3 (95% CI 8.0-246.7) in a current male smoker with a family history of SCD and cardiac hypertrophy.

CONCLUSIONS

There are specific features that differentiate the victims of SCD from survivors of an acute coronary event. Clustering of several variables, such as family history of SCD, smoking, cardiac hypertrophy and three-vessel CAD are alarm signals of a very high risk of SCD.

Non-invasive assessment of vulnerable plaque

BACKGROUND

Sudden cardiac death or unheralded acute coronary syndromes are common initial manifestations of coronary atherosclerosis and most such events occur at sites of non-flow limiting coronary atherosclerosis.

OBJECTIVE

Non-invasive detection of high-risk plaques might provide a means to improve risk stratification in primary and secondary prevention settings.

METHODS

This review is focused on the potential of multidetector computed tomography coronary angiography (MDCT-CA) to provide the opportunity to identify different aspects of plaque vulnerability throughout the coronary tree in an accurate, fast, safe and non-invasive manner.

CONCLUSION

Coronary artery calcium scoring, on top of established risk stratification, could potentially be a cost-effective strategy for primary prevention. MDCT-CA allows a non-invasive evaluation of several features commonly seen in vulnerable plaques and has demonstrated an independent prognostic value on a patient basis. The value of the technique itself might result, potentially, in a better estimation of the relative risk of an invidual plaque to rupture.

Is cold the new hot in sudden unexpected death in epilepsy? Effect of low temperature on heart rate of rats with epilepsy

Sudden unexpected death in epilepsy (SUDEP) is the commonest cause of seizure-related mortality in people with refractory epilepsy. Several risk factors for SUDEP are described; however, the importance of including low temperatures as risk factor for SUDEP was never explored. Based on this, the aim of this study was to evaluate the heart rate of rats with epilepsy during low temperature exposure. Our results showed that low temperature clearly increased the heart rate of rats with epilepsy. Taken together, we concluded that exposure to low temperatures could be considered important risk factors from cardiovascular abnormalities and hence sudden cardiac death in epilepsy.

Distribution and frequency of thin-capped fibroatheromas and ruptured plaques in the entire culprit coronary artery in patients with acute coronary syndrome as determined by optical coherence tomography

The aim of this study was to investigate the distribution and frequency of thin-capped fibroatheromas (TCFAs) within the entire length of culprit coronary arteries in patients with acute coronary syndrome. Our population was drawn from 43 consecutive patients with acute coronary syndrome (with or without ST-segment elevation) who underwent optical coherence tomography to visualize the entire culprit coronary artery using a nonocclusive optical coherence tomographic technique. Patients were categorized divided into a TCFA group or a no-TCFA group on the basis of the optical coherence tomographic findings. There were no differences in baseline characteristics or angiographic findings between the 2 groups. High-sensitive C-reactive protein in the TCFA group was significantly higher than in the no-TCFA group (median 3.3 mg/L, interquartile 3.1, vs 1.7 mg/L, interquartile 2.2, p = 0.03). Plaque rupture was found in 28 patients (65%) and multiple plaque ruptures in 5 patients (12%). Optical coherence tomogram revealed 21 TCFAs in 18 patients (42%). Multiple TCFAs were found in the same vessel in 3 patients (7%). The distribution of TCFAs in the right coronary arteries of our subject population was relatively even (proximal 2 [12%], mid 5 [29%], distal 3 [18%], p = 0.42), whereas TCFAs in the left anterior descending artery were common in proximal sites (proximal 6 [27%], mid 2 [9%], distal 0, p = 0.018). In conclusion, the use of optical coherence tomography to look for TCFAs and identify their distribution when combined with C-reactive protein may contribute to forming a strategy for preventing impending coronary events.

Preventing tomorrow's sudden cardiac death in epilepsy today: what should physicians know about this?

Approximately 1% of the population has epilepsy, the most common neurological disorder. Moreover, people with epilepsy are more likely to die prematurely than those without epilepsy, and the most common epilepsy-related category of death is sudden unexpected death in epilepsy (SUDEP). Information concerning risk factors for SUDEP is conflicting, but potential risk factors include: age, early onset of epilepsy, duration of epilepsy, uncontrolled seizures, seizure frequency, number of antiepileptic drugs and winter temperatures. Additionally, the cause of SUDEP is still unknown; however, the most commonly suggested mechanisms are cardiac abnormalities during and between seizures. This review discusses the epidemiology, risk factors, etiology, and preventative measures in the management of SUDEP.

Genetics of sudden cardiac arrest

Sudden cardiac arrest (SCA) due to ventricular arrhythmias is a major cause of mortality in western populations with up to 450,000 deaths in the United States each year. Although environmental factors clearly contribute to the determinants of SCA, familial aggregation studies and advances in the molecular genetics of inherited arrhythmias suggest that genetic factors confer susceptibility to SCA in the general population. Research in this area typically has focused on association of common genetic variants with intermediate phenotypes that predispose to SCA risk, such as QT interval, but few studies have examined genetic risk factors for SCA. We review the evidence for genetic susceptibility to SCA in the general population and focus on the studies published to date that have explored genetic risk factors.

Sudden cardiac death: prevalence, pathogenesis, and prevention

Sudden cardiac death (SCD), also known as sudden arrest, is a major health problem worldwide. It is usually defined as an unexpected death from a cardiac cause occurring within a short time in a person with or without preexisting heart disease. The pathogenesis of SCD is complex and multifaceted. A dynamic triggering factor usually interacts with an underlying heart disease, either genetically determined or acquired, and the final outcome is the development of lethal tachyarrhythmias or, less frequently, bradycardia. It has increasingly been highlighted that a reliable clinical and diagnostic approach might be effective to unmask the most important genetic and environmental factors, allowing the construction of a rational personalized medicine framework that can be applied in both the preclinical and clinical settings of SCD. The aim of the present article is to provide a concise overview of prevalence, pathogenesis, clinical presentation, and diagnostic approach to this challenging disorder.

Cardiac arrest with continuous mechanical chest compression during percutaneous coronary intervention

Mechanical chest compression may be necessary to make coronary intervention possible during resuscitation. We report our experience using the Lund University Cardiac Arrest System (LUCAS, Jolife, Lund, Sweden) which is a gas-driven sternal compression device that incorporates a suction cup for active decompression. During the last 13 months LUCAS has been used in our catheterisation laboratory to maintain adequate organ perfusion pressure in 13 patients with cardiac arrest or severe hypotension and bradycardia (male/female ratio 1.6, mean age 59+/-19). The mean compression time was 105+/-60min (range 45-240), and the mean systolic and diastolic blood pressure obtained was 81+/-23 and 34+/-21mmHg, respectively. Angiography and eventually percutanous coronary intervention was possible in all cases during ongoing automatic chest compression. Three patients survived the procedure, but no patients were discharged alive. In two cases we found inadequate flow in the anterior descending artery, and in one case the invasive measurements revealed inadequate coronary perfusion pressure. There were no excessive intra-thoracic or intra-abdominal injuries. We conclude that the LUCAS device is suitable during cardiac catheterisation and intervention, and the device ensures an adequate systemic blood pressure in most patients without life-threatening injuries.

Intravascular detection of inflamed atherosclerotic plaques using a fluorescent photosensitizer targeted to the scavenger receptor

Inflammation plays an important role in the pathophysiology of atherosclerotic disease. We have previously shown that the targeted photosensitizer chlorin (e(6)) conjugated with maleylated albumin (MA-ce6) is taken up by macrophages via the scavenger receptor with high selectivity. In a rabbit model of inflamed plaque in New Zealand white rabbits via balloon injury of the aorto-iliac arteries and high cholesterol diet we showed that the targeted conjugate showed specificity towards plaques compared to free ce6. We now show that an intravascular fiber-based spectrofluorimeter advanced along the -iliac vessel through blood detects 24-fold higher fluorescence in atherosclerotic vessels compared to control rabbits (p < 0.001 ANOVA). Within the same animals, signal derived from the injured iliac artery was 16-fold higher than the contralateral uninjured iliac (p < 0.001). Arteries were removed and selective accumulation of MA-ce6 in plaques was confirmed using: (1) surface spectrofluorimetry, (2) fluorescence extraction of ce6 from aortic segments, and (3) confocal microscopy. Immunohistochemical analysis of the specimens showed a significant correlation between MA-ce6 uptake and RAM-11 macrophage staining (R = 0.83, p < 0.001) and an inverse correlation between MA-ce6 uptake and smooth muscle cell staining (R = -0.74, p < 0.001). MA-ce6 may function as a molecular imaging agent to detect and/or photodynamically treat inflamed plaques.

Frequency and Distribution of Thin-Cap Fibroatheroma and Ruptured Plaques in Human Coronary Arteries

OBJECTIVES

Our purpose was to quantify the frequency and distribution of suspected vulnerable lesions, defined as thin-capped fibroatheroma (TCFA) and ruptured plaque, in human coronary artery autopsy specimens.

BACKGROUND

Most acute coronary events and sudden death are believed to arise from rupture of a TCFA followed by thrombosis. Although there is general agreement that clinical events are usually caused by focal lesions, there is considerable debate over the relative importance of focal versus systemic factors in the pathogenesis of atherosclerosis.

METHODS

We longitudinally sectioned coronary arteries from 50 whole hearts taken from patients (mean age 73 years, 64% men) dying of cardiovascular (n = 33), noncardiovascular (n = 13), and unknown (n = 4) causes. A total of 3,639 longitudinal segments of length 3 mm were sectioned from 148 arteries, accounting for 10.9 m of total tissue length. Specimens were classified on the basis of histology and computer-aided morphometry.

RESULTS

Twenty-three TCFA and 19 ruptured plaques were found (mean +/- SD: 0.46 +/- 0.95 and 0.38 +/- 0.70 per heart, respectively), and these lesions accounted for only 1.6% and 1.2%, respectively, of the total length of the coronary tree examined in patients dying of cardiovascular causes. The majority of TCFA and ruptured plaque localized in the proximal third of the major coronary arteries, and in 92% of cases these lesions clustered within 2 or fewer nonoverlapping 20-mm segments.

CONCLUSIONS

The suspected precursors of rupture-mediated thrombosis occur in a limited, focal distribution in the coronary arteries.

Hemodynamic factors and atheromatic plaque rupture in the coronary arteries: from vulnerable plaque to vulnerable coronary segment

Coronary plaque disruption with superimposed thrombosis is the underlying pathology in the acute coronary syndromes and sudden death. Coronary plaques are constantly stressed by a variety of mechanical and hemodynamic forces that may precipitate or 'trigger' disruption of vulnerable or, at extreme conditions, even stable plaques. This paper reviews the exciting new evidence on the hemodynamic factors that may play a role in this process and provides the rationale for the introduction of the concept of the vulnerable coronary segment in the study of acute coronary syndromes.