Mobilization of bone marrow-derived stem cells after myocardial infarction and left ventricular function

AIMS

Recent data suggest that the administration of bone marrow-derived stem cells (BMSC) might improve myocardial perfusion and left ventricular (LV) function after acute myocardial infarction (AMI). The aim of this study was to assess spontaneous mobilization of BMSC expressing the haematopoietic and endothelial progenitor cell-associated antigen CD34+ after AMI and its relation to post-infarction remodelling.

METHODS AND RESULTS

Peripheral blood concentration of CD34+ BMSC was measured by flow cytometry in 54 patients with AMI, 26 patients with chronic stable angina (CSA), and 43 normal healthy subjects. In patients with AMI, LV function was measured by 2D-echocardiography. Eighteen AMI patients were reassessed at 1 year. BMSC concentration was higher in patients with AMI (mean peak value: 7.04+/-6.27 cells/microL), than in patients with CSA (3.80+/-2.12 cells/microL, P=0.036) and in healthy controls (1.87+/-1.52 cells/microL, P<0.001). At multivariable analysis statin use (P<0.001), primary percutaneous intervention (P=0.048) and anterior AMI (P=0.05) were the only independent predictors of increased BMSC mobilization after AMI. In the 28 patients without subsequent acute coronary events reassessed at 1 year follow-up, CD34+ cell concentration was an independent predictor of global and regional improvement of LV function (r=0.52, P=0.004 and r=-0.41, P=0.03, respectively).

CONCLUSION

AMI is followed by enhanced spontaneous mobilization of BMSC, in particular, in patients on statin therapy and following a primary percutaneous intervention. More importantly persistent spontaneous mobilization of BMSC might contribute to determine a more favourable post-AMI remodelling.

Impact of Glycemic Variability on Chromatin Remodeling, Oxidative Stress, and Endothelial Dysfunction in Patients With Type 2 Diabetes and With Target HbA1c Levels

Intensive glycemic control (IGC) targeting HbA_1c fails to show an unequivocal reduction of macrovascular complications in type 2 diabetes (T2D); however, the underlying mechanisms remain elusive. Epigenetic changes are emerging as important mediators of cardiovascular damage and may play a role in this setting. This study investigated whether epigenetic regulation of the adaptor protein p66^Shc, a key driver of mitochondrial oxidative stress, contributes to persistent vascular dysfunction in patients with T2D despite IGC. Thirty-nine patients with uncontrolled T2D (HbA_1c >7.5%) and 24 age- and sex-matched healthy control subjects were consecutively enrolled. IGC was implemented for 6 months in patients with T2D to achieve a target HbA_1c of ≤7.0%. Brachial artery flow-mediated dilation (FMD), urinary 8-isoprostaglandin F_2α (8-isoPGF_2α), and epigenetic regulation of p66^Shc were assessed at baseline and follow-up. Continuous glucose monitoring was performed to determine the mean amplitude of glycemic excursion (MAGE) and postprandial incremental area under the curve (AUCpp). At baseline, patients with T2D showed impaired FMD, increased urinary 8-isoPGF_2α, and p66^Shc upregulation in circulating monocytes compared with control subjects. FMD, 8-isoPGF_2α, and p66^Shc expression were not affected by IGC. DNA hypomethylation and histone 3 acetylation were found on the p66^Shc promoter of patients with T2D, and IGC did not change such adverse epigenetic remodeling. Persistent downregulation of methyltransferase DNMT3b and deacetylase SIRT1 may explain the observed p66^Shc-related epigenetic changes. MAGE and AUCpp but not HbA_1c were independently associated with the altered epigenetic profile on the p66^Shc promoter. Hence, glucose fluctuations contribute to chromatin remodeling and may explain persistent vascular dysfunction in patients with T2D with target HbA_1c levels.

Adverse epigenetic signatures by histone methyltransferase Set7 contribute to vascular dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

Cellular studies showed that histone methyltransferase Set7 mediates high glucose-induced inflammation via epigenetic regulation of the transcription factor NF-kB. However, the link between Set7 and vascular dysfunction in patients with diabetes mellitus remains unknown. This study was designed to investigate whether Set7 contributes to vascular dysfunction in patients with type 2 diabetes mellitus (T2DM).

METHODS AND RESULTS

Set7-driven epigenetic changes on NF-kB p65 promoter and expression of NF-kB-dependent genes, cyclooxygenase 2 and inducible endothelial nitric oxide synthase, were assessed in peripheral blood mononuclear cells isolated from 68 subjects (44 patients with T2DM and 24 age-matched controls). Brachial artery flow-mediated dilation, 24-hour urinary levels of 8-isoprostaglandin F2α, and plasma adhesion molecules, intercellular cell adhesion molecule-1 and monocyte chemoattractant protein-1, were also determined. Experiments in human aortic endothelial cells exposed to high glucose were performed to elucidate the mechanisms of Set7-driven inflammation and oxidative stress. Set7 expression increased in peripheral blood mononuclear cells from patients with T2DM when compared with controls. Patients with T2DM showed Set7-dependent monomethylation of lysine 4 of histone 3 on NF-kB p65 promoter. This epigenetic signature was associated with upregulation of NF-kB, subsequent transcription of oxidant/inflammatory genes, and increased plasma levels of intercellular cell adhesion molecule-1 and monocyte chemoattractant protein-1. Interestingly, we found that Set7 expression significantly correlated with oxidative marker 8-isoprostaglandin F2α (r=0.38; P=0.01) and flow-mediated dilation (r=-0.34; P=0.04). In human aortic endothelial cells, silencing of Set7 prevented monomethylation of lysine 4 of histone 3 and abolished NF-kB-dependent oxidant and inflammatory signaling.

CONCLUSIONS

Set7-induced epigenetic changes contribute to vascular dysfunction in patients with T2DM. Targeting this chromatin-modifying enzyme may represent a novel therapeutic approach to prevent atherosclerotic vascular disease in this setting.

Relation between stress-induced myocardial perfusion defects on cardiovascular magnetic resonance and coronary microvascular dysfunction in patients with cardiac syndrome X

OBJECTIVES

The purpose of this study was to investigate whether a direct relation can be demonstrated between myocardial perfusion defects detected during dobutamine stress test (DST) by cardiovascular magnetic resonance (CMR) and impairment of coronary microvascular dilatory function in patients with cardiac syndrome X (CSX).

BACKGROUND

Despite the fact that coronary microvascular dysfunction has been shown in most patients with CSX, the ischemic origin of CSX remains debated. No previous study assessed whether a strict relation exists between abnormalities in myocardial perfusion and coronary microvascular dysfunction in CSX patients.

METHODS

Eighteen CSX patients (mean age 58 +/- 7 years, 7 men) and 10 healthy control subjects (mean age 54 +/- 8 years, 4 men) underwent myocardial perfusion study by gadolinium-enhanced CMR at rest and at peak DST (maximal dose 40 microg/kg/min). Coronary flow response (CFR) to adenosine (140 microg/kg/min in 90 s) in the left anterior descending (LAD) coronary artery was assessed by high-resolution transthoracic echo-Doppler and expressed as the ratio between coronary flow velocity at peak adenosine and at rest.

RESULTS

At peak DST, reversible perfusion defects on CMR were found in 10 CSX patients (56%) but in none of the control subjects (p = 0.004). The CFR to adenosine in the LAD coronary artery was lower in CSX patients than in control subjects (2.03 +/- 0.63 vs. 3.29 +/- 1.0, p = 0.0004). The CSX patients with DST-induced myocardial perfusion defects in the LAD territory on CMR had a lower CFR to adenosine compared with those without perfusion defects in the LAD territory (1.69 +/- 0.5 vs. 2.31 +/- 0.6, p = 0.01). A significant correlation was found in CSX patients between CFR to adenosine and a DST perfusion defect score on CMR in the LAD territory (r = -0.45, p = 0.019).

CONCLUSIONS

Our data concurrently show DST-induced myocardial perfusion defects on CMR and reduced CFR in the LAD coronary artery territory in CSX patients, thus giving strong evidence that a dysfunction of coronary microcirculation resulting in myocardial perfusion abnormalities is present in these patients.

Incremental prognostic value of serum levels of troponin T and C-reactive protein on admission in patients with unstable angina pectoris

Management of unstable angina is largely determined by symptoms, yet some symptomatic patients stabilize, whereas others develop myocardial infarction after waning of symptoms. Therefore, markers of short-term risk, available on admission, are needed. The value of 4 prognostic indicators available on admission (pain in the last 24 hours, electrocardiogram [ECG], troponin T, and C-reactive protein [CRP]), and of Holter monitoring available during the subsequent 24 hours was analyzed in 102 patients with Braunwald class IIIB unstable angina hospitalized in 4 centers. The patients were divided into 3 groups: group 1, 27 with pain during the last 24 hours and ischemic electrocardiographic changes; group 2, 45 with pain or electrocardiographic changes; group 3, 30 with neither pain nor electrocardiographic changes. Troponin T, CRP, ECG on admission, and Holter monitoring were analyzed blindly in the core laboratory. Fifteen patients developed myocardial infarction: 22% in group 1, 13% in group 2, and 10% in group 3. Twenty-eight patients underwent revascularization: 37% in group 1, 35% in group 2, and 7% in group 2 (p <0.01 between groups 1 or 2 vs group 3). Myocardial infarction was more frequent in patients with elevated troponin T (50% vs 9%, p=0.001) and elevated CRP (24% vs 4%, p= 0.01). Positive troponin T or CRP identified all myocardial infarctions in group 3. Only 1 of 46 patients with negative troponin T and CRP developed myocardial infarction. Among the indicators available on admission, multivariate analysis showed that troponin T (p=0.02) and CRP (p=0.04) were independently associated with myocardial infarction. Troponin T had the highest specificity (92%), and CRP the highest sensitivity (87%). Positive results on Holter monitoring were also associated with myocardial infarction (p=0.003), but when added to troponin T and CRP, increased specificity and positive predictive value by only 3%. Thus, in patients with class IIIB unstable angina, among data potentially available on admission, serum levels of troponin T and CRP have a significantly greater prognostic accuracy than symptoms and ECGs. Holter monitoring, available 24 hours later, adds no significant information.

Chromosome 18q allelic loss and prognosis in stage II and III colon cancer

The prognostic significance of chromosome 18q allelic loss was evaluated in a series of 118 patients with curatively resected TNM stage II or stage III colon cancer. Chromosome 18q status was determined on frozen tumour samples, using microsatellite markers and the polymerase chain reaction (PCR). Mean follow-up in surviving patients was 75.9 months. Chromosome 18q allelic loss was significantly related to tumour site, extramural venous invasion, flow cytometric nuclear DNA content and p53 protein expression. Patients whose tumour had no evidence of chromosome 18q allelic loss showed a better disease-free and overall survival than patients whose tumour demonstrated 18q allelic loss. When patients were stratified by tumour stage, a significant survival advantage for patients whose tumour had no allelic loss on chromosome 18q was observed in stage II as well as in stage III disease. In particular, patients with stage II disease whose tumour had no chromosome 18q allelic loss demonstrated an excellent clinical outcome, with a 5-year disease-free survival rate of 96%. In contrast, the 5-year disease-free survival rate of patients with stage II disease and chromosome 18q allelic loss was only 54%. In multivariate analysis, status of chromosome 18q was the only significant independent prognostic factor for both disease-free and overall survival. These results indicate that assessment of chromosome 18q status provides relevant prognostic information in colon cancer and might be employed in the selection of patients for adjuvant therapy.

Atenolol versus amlodipine versus isosorbide-5-mononitrate on anginal symptoms in syndrome X

The effects of a beta blocker (atenolol), a calcium antagonist (amlodipine), and a nitrate (isosorbide-5-mononitrate) on anginal symptoms in 10 patients with syndrome X were assessed in a crossover, double-blind, randomized trial. Only atenolol was found to significantly improve chest pain episodes, suggesting that it should be the preferred drug when starting pharmacologic treatment of patients with syndrome X.

Plasma protein acute-phase response in unstable angina is not induced by ischemic injury

BACKGROUND

Elevated levels of C-reactive protein (CRP) are associated with an unfavorable clinical outcome in patients with unstable angina. To determine whether ischemia-reperfusion injury causes this acute-phase response, we studied the temporal relation between plasma levels of CRP and ischemic episodes in 48 patients with unstable angina and 20 control patients with active variant angina, in which severe myocardial ischemia is caused by occlusive coronary artery spasm.

METHODS AND RESULTS

Blood samples were taken on admission and subsequently at 24, 48, 72, and 96 hours. All patients underwent Holter monitoring for the first 24 hours and remained in the coronary care unit under ECG monitoring until completion of the study. On admission, CRP was significantly higher in unstable angina than in variant angina patients (P < .001). In unstable angina, 70 ischemic episodes (1.5 +/- 2 per patient) and in variant angina 192 ischemic episodes (9.6 +/- 10.7 per patient) were observed during Holter monitoring (P < .001), for a total ischemic burden of 14.8 +/- 30.2 and 44.4 +/- 57.2 minutes per patient, respectively (P < .001). The plasma concentration of CRP did not increase in either group during the 96 hours of study, even in patients who had episodes of ischemia lasting > 10 minutes.

CONCLUSIONS

The normal levels of CRP in variant angina, despite a significantly larger number of ischemic episodes and greater total ischemic burden, and the failure of CRP values to increase in unstable angina indicate that transient myocardial ischemia, within the range of duration observed, does not itself stimulate an appreciable acute-phase response.

Cardiac syndrome X: a critical overview and future perspectives

The classic definition of cardiac syndrome X (CSX) seems inadequate both for clinical and research purposes and should be replaced with one aimed at including a sufficiently homogeneous group of patients with the common plausible pathophysiological mechanism of coronary microvascular dysfunction. More specifically, CSX should be defined as a form of stable effort angina, which, according to careful diagnostic investigation, can reasonably be attributed to abnormalities in the coronary microvascular circulation.

Abnormal cardiac adrenergic nerve function in patients with syndrome X detected by [123I]metaiodobenzylguanidine myocardial scintigraphy

BACKGROUND

Previous studies have suggested that an abnormal cardiac adrenergic tone may have a pathophysiological role in syndrome X (effort angina, positive exercise testing, angiographically normal coronary arteries).

METHODS AND RESULTS

To evaluate cardiac adrenergic nerve function, we performed [123I]metaiodobenzylguanidine (MIBG) myocardial scintigraphy in 12 patients with syndrome X and 10 control subjects. Cardiac MIBG uptake was assessed by the heart/mediastinum (H/M) ratio and by an MIBG uptake defect score (higher values=lower uptake). In syndrome X patients, we also correlated MIBG scintigraphic findings with stress myocardial perfusion as assessed by 201Tl scintigraphy. An inferior MIBG defect was observed in only 1 control subject, whereas 9 patients (P<.01) showed MIBG defects. The heart was totally or almost totally invisible on MIBG images in 5 patients, and predominantly regional defects were observed in 4. The H/M ratio was lower (1.70+/-0.6 versus 2.2+/-0.3, P=.03) and MIBG uptake defect score higher (35+/-31 versus 4+/-2, P=.003) in syndrome X patients. Reversible stress thallium perfusion defects were found in 62% of patients with MIBG defects but in no patient with normal MIBG uptake. MIBG defects persisted unchanged in 7 patients at a 5+/-3-month follow-up study.

CONCLUSIONS

In this study, obvious defects in global and/or regional cardiac MIBG uptake, indicating an abnormal cardiac adrenergic nerve function, were detected in 75% of patients with syndrome X. These findings strongly support the cardiac origin of chest pain in syndrome X, although the mechanisms and the pathophysiological meaning of the abnormal cardiac MIBG uptake in these patients deserve further investigation.

Prognostic role of heart rate variability in patients with a recent acute myocardial infarction

A low heart rate variability (HRV) has been shown to be a powerful predictor of cardiac events in patients surviving an acute myocardial infarction (MI), but it is not clear yet which among the HRV parameters has the best predictive value. Time domain and frequency domain HRV was assessed on 24-hour predischarge Holter recording of 239 patients with a recent MI. Patients were followed up for 6 to 54 months (median 28), during which 26 deaths (11%) occurred, 19 of which were cardiac in origin and 12 were sudden. Most HRVs did not show any difference between patients with or without mortality end points, but the average low-frequency and low-frequency/high-frequency ratio was lower in patients with events. However, when dichotomized according to cut points that maximized the risk of sudden death, several HRVs were significantly predictive of clinical end points. Overall, the mean of the standard deviations of all RR intervals for all 5-minute segments and the standard deviation of the mean RR intervals for all 5-minute segments were the time domain variables most significantly associated with mortality end points, whereas very low frequency was the most predictive frequency domain variable. Compared with the best time domain variables, very low frequency showed a better sensitivity (0.27 to 0.42 vs 0.19 to 0.33) for end points with only a small loss in specificity (0.92 vs 0.96). On multivariate Cox proportional analysis, a left ventricular ejection fraction <40% and a number of ventricular premature beats > or = 10/hour were the most powerful independent predictors for all end points, whereas no HRV was independently associated with the events. A low frequency/high frequency ratio < 1.05 only had a borderline association with sudden death (RR = 2.86, p = 0.076). Our data show a strong association between HRV and mortality in patients surviving a recent MI, with a slight better sensitivity of frequency domain analysis. In our study, however, HRV did not add independent prognostic information to more classic prognostic variables (e.g., left ventricular function and ventricular arrhythmias).

Autonomic changes associated with spontaneous coronary spasm in patients with variant angina

OBJECTIVES

This study sought to investigate whether changes in nervous autonomic tone may have a role in the mechanisms triggering spontaneous coronary spasm in variant angina.

BACKGROUND

Previous studies have suggested that both sympathetic and vagal activation may act as a trigger of epicardial artery spasm in patients with variant angina, but the actual role of autonomic changes in spontaneous coronary spasm remains unknown.

METHODS

We analyzed the changes in heart rate variability associated with episodes of ST segment elevation detected on Holter monitoring in 23 patients with variant angina (18 men, 5 women; mean [+/-SD] age 59 +/- 12 years). For study purposes, episodes of transmural ischemia lasting > or = 3 min and without any ST segment changes in the previous 40 min were selected for analysis. Heart rate variability indexes were calculated at 2-min intervals, at 30,15,5 and 1 min before ST elevation and at peak ST segment elevation. Ninety-three of 239 total ischemic episodes (39%) fulfilled the inclusion criteria.

RESULTS

The results showed that 1) high frequency (HF) (0.04 to 0.15 Hz), a heart rate variability index specific for vagal activity, decreased in the 2 min preceding ST segment elevation (p < 0.001) and returned to basal levels at peak ST segment elevation; 2) heart rate and low frequency (0.04 to 0.15 Hz), which are partially correlated with sympathetic activity, showed a significant increase at peak ST segment elevation (p < 0.001 for both); 3) the pattern of the HF reduction before ST segment elevation was consistently confirmed in several subgroups of ischemic episodes, including those of patients with or without coronary stenoses, those of patients with anterior or inferior ST segment elevation, those occurring during daily or nightly hours and silent episodes. There were no significant variations in heart rate variability in control periods selected from Holter tapes of patients and before ST segment elevation induced by balloon inflation in 20 patients undergoing coronary angioplasty.

CONCLUSIONS

Our data show that changes in autonomic tone are likely to contribute to trigger or predispose to epicardial spasm. In particular, although not excluding an active role for adrenergic mechanisms, our data suggest that a vagal withdrawal may often be a component of the mechanisms leading to spontaneous coronary vasospasm.

Assessment and pathophysiology of microvascular disease: recent progress and clinical implications

The development of novel, non-invasive techniques and standardization of protocols to assess microvascular dysfunction have elucidated the key role of microvascular changes in the evolution of cardiovascular (CV) damage, and their capacity to predict an increased risk of adverse events. These technical advances parallel with the development of novel biological assays that enabled the ex vivo identification of pathways promoting microvascular dysfunction, providing novel potential treatment targets for preventing cerebral-CV disease. In this article, we provide an update of diagnostic testing strategies to detect and characterize microvascular dysfunction and suggestions on how to standardize and maximize the information obtained from each microvascular assay. We examine emerging data highlighting the significance of microvascular dysfunction in the development CV disease manifestations. Finally, we summarize the pathophysiology of microvascular dysfunction emphasizing the role of oxidative stress and its regulation by epigenetic mechanisms, which might represent potential targets for novel interventions beyond conventional approaches, representing a new frontier in CV disease reduction.

Carotid Artery Stenting

BACKGROUND AND PURPOSE

The prevention of stroke and the correct treatment of carotid artery stenosis represent today a major debate in cardiovascular medicine. Beside carotid endarterectomy, carotid angioplasty and stenting is becoming more widely performed for the treatment of severe carotid obstructive disease, and is now accepted as a less invasive technique that may provide an alternative for selected patients, particularly those with significant comorbidities. An Italian multidisciplinary task force, in which converged the most representative scientific societies involved in carotid treatment, was created to provide neurologists, radiologist, cardiologists, vascular surgeons, and all those involved in prevention and treatment of carotid disease with a simple, clear and updated evidence-based consensus document.

SUMMARY OF REVIEW

This First Consensus Document of the ICCS (Italian Consensus Carotid Stenting)/SPREAD group addressed the main issues related to methodology, definition of symptomatic and asymptomatic carotid stenosis, indication and procedures for carotid artery stenting, including the use of devices for preventing procedural embolic complications. Special attention was paid to credentials and competency for physicians qualifications to perform vascular angioplasty and stent placement, including training, acceptable complication rates and certification.

CONCLUSIONS

As any guideline or consensus statement, also this document is valid as long as the evidence on which it is based remains up-to-date. In such a fast-evolving field of medicine as the management of carotid stenosis, it is mandatory to stimulate a continuous and fruitful discussion among all the professionals involved in this very evolutionary field.

CagA antigen of Helicobacter pylori and coronary instability: insight from a clinico-pathological study and a meta-analysis of 4241 cases

BACKGROUND

Cytotoxin-associated gene-A (CagA) antigen is expressed by some virulent strains of Helicobacter pylori (H. pylori). The role of CagA antigen in coronary instability is unknown. We performed a clinico-pathological study and a meta-analysis in the attempt to shed new light on this complex issue.

METHODS

In the clinico-pathological study, 38 patients with unstable angina (UA), 25 patients with stable angina (SA), 21 patients with normal coronary arteries (NCA) and 50 age and sex matched healthy volunteers were enrolled. Serology for CagA was assessed in all patients. Specimens of atherosclerotic plaques were obtained from all patients by directional coronary atherectomy, and prepared for immunohistochemistry using anti-CagA monoclonal antibodies. The meta-analysis includes 9 studies assessing the association between seropositivity to CagA strains and acute coronary events.

RESULTS

The titre of anti-CagA antibodies was significantly higher in patients with unstable angina (161+/-90 RU/ml) compared to those with stable angina (83+/-59 RU/ml p<0.02), NCA (47.3+/-29 RU/ml p<0.01) and healthy controls (73+/-69 p<0.02). Anti-CagA antibodies recognized antigens localized inside coronary atherosclerotic plaques in all specimens from both stable and unstable patients. In the meta-analysis, seropositivity to CagA was significantly associated with the occurrence of acute coronary events with an odds ratio (OR) of 1.34 (95% CI, 1.15-1.58, p=0.0003).

CONCLUSIONS

Taken together these findings suggest that in a subset of patients with unstable angina, an intense immune response against CagA-positive H. pylori strains might be critical to precipitate coronary instability mediated by antigen mimicry between CagA antigen and a protein contained in coronary atherosclerotic plaques.

Medullary-type poorly differentiated adenocarcinoma of the large bowel: a distinct clinicopathologic entity characterized by microsatellite instability and improved survival

PURPOSE

Recent studies suggest the existence of a distinct class of poorly differentiated large bowel adenocarcinomas, usually termed medullary-type adenocarcinomas (MTAs). The aim of the present study was to accurately define the clinical, histopathologic, biologic, and genetic features of this tumor type.

MATERIALS AND METHODS

Among 1,265 surgically resected sporadic colorectal carcinomas, 45 MTAs were identified on the basis of the following criteria: predominantly solid growth pattern (at least 70% of the tumor area) and lack of marked nuclear pleomorphism. The clinicopathologic, biologic, and genetic characteristics of MTAs were compared with those of a series of 457 common glandular colorectal adenocarcinomas.

RESULTS

The significantly different clinicopathologic features of MTAs were proximal location, large size, invasion into adjacent organs, expanding pattern of growth, low incidence of distant metastases, more frequent conspicuous peritumoral lymphocytic infiltration, and Crohn's-like lymphoid reaction. Furthermore, young patients with MTAs often demonstrated a family history highly suggestive of a hereditary background. Unlike glandular adenocarcinomas, the large majority of MTAs were DNA diploid by flow cytometric analysis (21 of 25, 84%) and p53 negative by immunohistochemistry (36 of 41, 87.8%). In addition, 18 of the 20 MTAs examined by DNA microsatellite analysis demonstrated widespread microsatellite instability (90% of cases). Patients with MTAs showed a better clinical outcome with respect to patients with common poorly differentiated adenocarcinomas (PDAs) (P <.0001) and well- or moderately differentiated adenocarcinomas (WMDAs) (P =.133). In particular, none of the 33 patients with completely resectable stage II and III MTAs developed tumor recurrence during the observation period. Conversely, 24.7% of patients with stage II and III WMDAs and 48.9% of patients with stage II and III PDAs, who had undergone curative surgical resection, died of recurrent disease (P =.01 and P <.0001, respectively).

CONCLUSION

All these data strongly indicate that MTAs represent a distinct pathologic entity, with specific histologic appearance and peculiar clinical and genetic features. These tumors need to be classified separately from other poorly differentiated colorectal carcinomas.

Thrombin-inhibiting perfluorocarbon nanoparticles provide a novel strategy for the treatment and magnetic resonance imaging of acute thrombosis

BACKGROUND

As a regulator of the penultimate step in the coagulation cascade, thrombin represents a principal target of direct and specific anticoagulants.

OBJECTIVE

A potent thrombin inhibitor complexed with a colloidal nanoparticle was devised as a first-in-class anticoagulant with prolonged and highly localized therapeutic impact conferred by its multivalent thrombin-absorbing particle surface.

METHODS

PPACK (Phe[D]-Pro-Arg-Chloromethylketone) was secured covalently to the surface of perfluorocarbon-core nanoparticle structures. PPACK and PPACK nanoparticle inhibition of thrombin were assessed in vitro via thrombin activity against a chromogenic substrate. In vivo antithrombotic activity of PPACK, heparin, non-functionalized nanoparticles and PPACK nanoparticles was assessed through intravenous (i.v.) administration prior to acute photochemical injury of the common carotid artery. Perfluorocarbon particle retention in extracted carotid arteries from injured mice was assessed via (19) F magnetic resonance spectroscopy (MRS) and imaging (MRI) at 11.7 T. Activated partial thromboplastin time (APTT) measurements determined the systemic effects of the PPACK nanoparticles at various times after injection.

RESULTS

 An optical assay verified that PPACK nanoparticles exceeded PPACK's intrinsic activity against thrombin. Application of an in vivo acute arterial thrombosis model demonstrated that PPACK nanoparticles outperformed both heparin (P=0.001) and uncomplexed PPACK (P = 0.0006) in inhibiting thrombosis. (19) F MRS confirmed that PPACK nanoparticles specifically bound to sites of acute thrombotic injury. APTT normalized within 20 min of PPACK nanoparticles injection.

CONCLUSIONS

 PPACK nanoparticles present thrombin-inhibiting surfaces at sites of acutely forming thrombi that continue to manifest local clot inhibition even as systemic effects rapidly diminish and thus represent a new platform for localized control of acute thrombosis.

Patients with acute myocardial infarction and non-obstructive coronary arteries: safety and prognostic relevance of invasive coronary provocative tests

Aims

Functional alterations of epicardial coronary arteries or coronary microcirculation represent a frequent cause of myocardial infarction and non-obstructive coronary arteries (MINOCA). We aimed at assessing the prognostic value of intracoronary provocative tests in patients presenting with MINOCA and in which other causes of MINOCA have been excluded.

Methods and results

We prospectively evaluated patients with a diagnosis of MINOCA, excluding patients with aetiologies other than suspected coronary vasomotor abnormalities. Immediately after coronary angiography, an invasive provocative test using acetylcholine or ergonovine was performed. The incidence of death from any cause, cardiac death, and recurrence of acute coronary syndrome (ACS) was assessed at follow-up. We also assessed angina status using Seattle Angina Questionnaires (SAQ). We enrolled 80 consecutive patients [mean age 63.0 ± 10.7 years, 40 (50%) male]. Provocative test was positive in 37 (46.2%) patients without any complication. Among patients with a positive test, epicardial spasm was detected in 24 (64.9%) patients and microvascular spasm in 13 (35.1%) patients. After a median follow-up of 36.0 (range 12.0-60.0) months, patients with a positive test had a significantly higher occurrence of death from any cause [12 (32.4%) vs. 2 (4.7%); P = 0.002], cardiac death [7 (18.9%) vs. 0 (0.0%); P = 0.005], and readmission for ACS [10 (27.0%) vs. 3 (7.0%); P = 0.015] as well as a worse angina status as assessed by SAQ [Seattle score: 88.0 (33.0-100.0) vs. 100.0 (44.0-100.0); P = 0.001] when compared with patients with a negative test.

Conclusions

We demonstrate that in patients presenting with MINOCA and suspected coronary vasomotor abnormalities, a positive provocative test for spasm is safe and identifies a high-risk subset of patients.

Relation of heart rate variability to serum levels of C-reactive protein in patients with unstable angina pectoris

Heart rate variability (HRV) and systemic markers of inflammation have prognostic value in patients with unstable angina pectoris (UAP). However, it is unknown whether any relation exists between HRV parameters and indexes of inflammation in this clinical context. We assessed HRV on 24-hour electrocardiographic Holter recordings, performed within 24 hours of admission, and measured C-reactive protein (CRP) serum levels by a high-sensitivity assay on admission, in 531 patients with UAP (65+/-10 years of age; 347 men) who were enrolled in the prospective multicenter study Stratificazione Prognostica dell'Angina Instabile (SPAI). A significant inverse correlation was found between CRP levels and all HRV parameters, with the highest r coefficient shown with SD of all RR intervals (r= -0.23; p<0.001) in the time domain and with very low-frequency amplitude (r= -0.22; p<0.001) in the frequency domain. When patients were categorized into 4 groups according to CRP quartile levels, statistically significant lower HRV values were observed in the upper CRP quartile. On separate multiple regression analyses, including the most important clinical and laboratory variables, SD of all RR intervals and very low-frequency amplitude were the most significant predictors of increasing CRP levels (p<0.001 for the 2 comparisons). In contrast, in models with SD of all RR intervals and very low-frequency amplitude as dependent variables, CRP was a strong predictor of impaired cardiac autonomic function (p<0.001 for the 2 comparisons). Thus, our data show that, in patients with UAP, high levels of serum CRP levels are significantly associated with decreased HRV, suggesting a possible pathophysiologic link between cardiac autonomic dysfunction and inflammatory activity.

Acute effects of nitrates on exercise testing in patients with syndrome X. Clinical and pathophysiological implications

BACKGROUND

Sublingual nitrates are much more effective in relieving angina pectoris in patients with coronary artery disease than in patients with syndrome X, but it is not known whether their effect on exercise tolerance is also different in these two groups of patients.

METHODS AND RESULTS

Treadmill exercise testing was performed before and after administration of sublingual isosorbide dinitrate (ISDN, 5 mg) in 18 patients with syndrome X (effort angina and normal coronaries, group X) and in 33 patients with documented coronary artery disease (group C). As a selection criterion, all patients had ST-segment depression > or = 1 mm on the control exercise test. Compared with the control test, the main differences in the two groups observed during the exercise test after administration of ISDN were (1) heart rate at 1-mm ST-segment depression was higher (126 +/- 25 versus 104 +/- 15 beats per minute [bpm], P < .01) in group C, whereas it was not different (125 +/- 15 versus 126 +/- 16 beats per minute) in group X; (2) the rate-pressure product at 1-mm ST-segment depression, the time to 1-mm ST-segment depression, and the exercise duration were significantly improved in group C (P < .01 for all) but were worsened in group X (18,047 +/- 4159 versus 20,535 +/- 4507 bpm . mm Hg, P = .014; 268 +/- 312 versus 429 +/- 214 seconds, P < .01; 494 +/- 279 versus 622 +/- 194 seconds, P = .013, respectively); (3) a normalization of the ECG (no ST-segment depression) was obtained in 10 patients (30%) of group C but in only 1 (5%) of group X (P < .01); (4) angina was prevented in 10 of 19 patients of group C but in no patient of group X (P < .01).

CONCLUSIONS

In patients presenting with anginal chest pain, the effects of sublingual nitrates on exercise testing appear to be clinically useful to distinguish patients with coronary artery stenoses from patients with syndrome X. Indeed, worsening of exercise tolerance is highly predictive of normal coronary arteries. Furthermore, the failure of nitrates to improve exercise tolerance in patients with syndrome X suggests that a deficiency in coronary prearteriolar nitric oxide production is unlikely to play a key role in the pathophysiology of the syndrome.

Impairment of cardiac autonomic function in patients with Duchenne muscular dystrophy: relationship to myocardial and respiratory function

BACKGROUND

Previous studies reported an impairment of nervous autonomic activity in patients with Duchenne muscular dystrophy (DMD). However, the relationship of the autonomic dysfunction to the impairment of cardiac mechanical function and of respiratory failure is not completely understood.

METHODS

We evaluated cardiac autonomic function by time- and frequency-domain heart rate variability (HRV) analysis on 24-hour Holter recordings in 60 patients with DMD (16.8 +/- 4.8 years) and 28 healthy control patients (15.2 +/- 4.6 years, P = not significant). The circadian rhythm of R-R interval, low frequency, high frequency, and low-frequency/high-frequency ratio was also assessed. In all patients, left ventricular ejection fraction was measured by 2D echocardiography; respiratory function was assessed by spirometry.

RESULTS

All HRV parameters were lower in patients with DMD than in control subjects, with the percentage of differences between adjacent R-R intervals >50 ms (11.6% +/- 8.5% vs 27.3% +/- 14.1%, P =.00001) and high frequency (23.9 +/- 10.3 ms vs 36.1 +/- 12.2 ms, P =.0001) showing the strongest differences. A significant circadian rhythm of HRV variables was present in both groups, but it was considerably flattened in patients with DMD. There was no correlation between left ventricular ejection fraction and HRV indexes except for a weak correlation with high frequency (r = 0.30, P =.02) and with low-frequency to high-frequency ratio (r = -0.29, P <.03). Similarly modest correlations were found between forced vital capacity and high frequency (r = 0.4, P =.007) and low-frequency/high-frequency ratio (r = -0.32, P =.026). Multiple regression analysis did not show any independent predictive variable for the autonomic impairment.

CONCLUSIONS

Our data show a marked impairment of cardiac autonomic function in patients with DMD, which appears to mainly involve the parasympathetic branch and appears to have a multifactorial origin.

Electrical and autonomic cardiac function in patients with Dravet syndrome

Dravet syndrome (DS) is an epileptic encephalopathy related mainly to mutations in the SCN1A gene, encoding for neuronal sodium channels. Patients with DS have a high risk of sudden unexpected death in epilepsy (SUDEP). In this study we investigated whether patients with DS present abnormalities in electrical and autonomic cardiac function. To this aim we assessed ventricular repolarization and heart rate variability (HRV) on standard electrocardiography (ECG) and on 24-h ECG Holter monitoring, respectively, in 20 patients affected by DS (6.8 ± 4 years, 11 female). As age- and sex-matched control groups, we also studied 20 patients with other epileptic syndromes receiving antiepileptic drugs (ES/AED, 6.0 ± 5 years, 12 female), 20 patients with other epileptic syndromes without treatment (ES/no-AED, 6.7 ± 4 years, 10 female), and 20 healthy children (HC, 7.2 ± 5 years, 11 females). Data analysis showed that patients with DS had depressed HRV variables compared to both ES patients (ES/AED and ES/no-AED) and HC control group, whereas no significant differences in HRV variables were found between ES patients (with and without treatment) and HC. There was no significant difference between patients with DS and all the other control groups in RR intervals, QT, and QTc interval analysis. In conclusion, DS patients display an imbalance of cardiac autonomic function toward a relative predominance of adrenergic tone compared to both healthy children and patients with other forms of epilepsy, independent of antiepileptic therapy. Follow-up studies should clarify the clinical significance of this autonomic impairment and whether HRV analysis can be helpful in predicting the risk of sudden death in patients with DS.

Circadian variation of ventricular tachycardia in acute myocardial infarction

Circadian rhythms have been described both for acute myocardial infarction (AMI) and sudden death. In this study the diurnal distribution of ventricular tachycardia (VT) in patients with AMI was analyzed. Ninety-four AMI patients with greater than or equal to 1 VT on Holter electrocardiographic monitoring who were not taking antiarrhythmic drugs were studied. Forty-seven patients had a recent AMI (group A) and 47 an old AMI (group B). Chronobiologic analysis was made by single cosinor method. There were 157 VTs (mean 1.67 VTs/patient, range 1 to 10) in the 94 patients: 70 in group A and 87 in group B. A significant circadian rhythm of VT was found in the total population with acrophase at 2:29 P.M. The hourly distribution of VT showed a tendency to bimodality, which seemed due to a different time of peak VT occurrence in group A (significant rhythm with acrophase at 4:40 P.M.) and group B (significant rhythm with acrophase at 12:39 P.M.). Thus, the hourly VT frequency in patients with AMI has a significant circadian variation with the highest occurrence in the awake hours, similar to the rhythms described for AMI and sudden death.