Measurement of the Positive Muon Anomalous Magnetic Moment to 0.20 ppm

We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω[over ˜]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ω[over ˜]_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.

Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ω[over ˜]_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ω[over ˜]_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.

1177 The additive prognostic value of end-systolic pressure-volume relation by CMR in patients with with known or suspected coronary artery disease

Background

The variation between rest and peak stress end-systolic pressure-volume relation is an afterload-independent index of left ventricular contractility. This index is easily obtained during routine stress echocardiography but can be derived also during a stress cardiovascular magnetic resonance (CMR) exam, that is the gold standard for the quantification of biventricular volumes.

Purpose

The aim of this study was to assess for the first time the prognostic value ofdelta rest-stress ESPVR (DESPVR) by dipyridamole stress-CMR in patients with known or suspected coronary artery disease (CAD).

Methods

One hundred and sixty-six consecutive patients (37 females, main age 61.96 ± 10.05 years) who underwent dipyridamole stress-CMR in a high volume CMR Laboratory were considered. Abnormal wall motion and perfusion at rest and after dipyridamole were analysed. Macroscopic myocardial fibrosis was detected by the late gadolinium enhancement (LGE) technique. The ESPVR was evaluated at rest and peak stress from raw measurement of systolic arterial pressure by cuff sphygmomanometer and end-systolic volume by biplane Simpson method.

Results

An abnormal stress CMR was found in 39 (23.5%) patients; 24 patients had a reversible stress perfusion defect in at least one myocardial segment and 15 a reversible stress perfusion defect plus worsening of stress wall motion in comparison with rest. Myocardial fibrosis was detected in 69 patients (41.6%). A DESPVR < 0.009 was detected in 74 patients (44.6%).

During a median follow up of 55.51 months (IQ range 33.20 months), 54 patients (32.5%) experienced major cardiac events: 5 deaths, 2 ventricular arrhythmias, 18 coronary syndromes, and 29 heart failure hospitalization.Reversible perfusion deficit, DESPVR < 0.009, diabetes and family history were significant univariate prognosticators. In the multivariate analysisthe independent predictive factors were reversible perfusion deficit (hazard ratio-HR = 2.17, P = 0.010), DESPVR < 0.009 (HR = 1.92, P = 0.028) and diabetes (HR = 2.42, P = 0.004). The Kaplan–Meier curve for DESPVR is shown in Figure 1. The log-rank test revealed a significant difference (P = 0.003).

Conclusions

DESPRV assessed by CMR provides a prognostic stratification in patients with known or suspected coronary artery disease, in addition to that supplied by reversible perfusion deficit and diabetes.

Abstract 1177 Figure 1

The Use of First Generation versus Second Generation Antipsychotics as Add-on or as Switch Treatment and its Effect on QTc Interval: The Italian Experience in a Real-World Setting

Some psychotropic drugs are connected with prolongation of the QT interval, torsade de pointes and sudden death. Recent data suggest that with regard to this adverse effect, the atypical antipsychotic drugs are no safer than the older drugs. The purpose of this study is to evaluate the different use of first generation versus second generation antipsychotics as add-on (Group I) or switch treatment (Group II) and its effect on QTc interval in a sample of schizophrenic and bipolar inpatients without medical illness. All patients had been evaluated twice by using ECG: on admission and after two weeks of hospitalization. Exclusions criteria were: abnormalities in levels of potassium, magnesium and calcium, cardiovascular and metabolic diseases, alcohol or drug abuse. We found a significant (p < 0.01) greater use of first generation antipsychotic in Group I (73.80%) than in the Group II (33.33%). Also Group I showed a significant increase (p < 0.0001) in total chlorpromazine equivalent (476. 78 ± 448.80 mg/day vs 845.48 ± 491.64 mg/day) and in QTc interval (369.14 ± 33.75 ms vs 387.09 ± 31.97 ms), while we did not find any statistical difference in Group II during hospitalization. Our results, in spite of the small sample size, indicate that antipsychotic add-on can increase QTc interval more than switching to other antipsychotic in psychiatric patients without other risk factors.

Intermittent warm blood cardioplegia induces the expression of heat shock protein-72 by ischemic myocardial preconditioning

OBJECTIVE

Recent studies have demonstrated that the induction of heat shock protein-72 (HSP72) by different stimuli preserves the heart function after cardioplegic arrest. Based on these findings, we investigated whether intermittent warm blood cardioplegia would induce changes in the myocardial expression of HSP72.

METHODS

Forty patients scheduled for aortocoronary bypass were randomly assigned to receive either cold or warm intermittent blood cardioplegia. In all patients HSP72 and HSP72 mRNA were assayed in biopsies from the right atrium at baseline, and during the reperfusion period. Plasma CK-MB and troponin-T, and myocardial oxygen extraction and lactate release were also measured.

RESULTS

In both groups, myocardial expression of HSP72 increased throughout the reperfusion period, but the values of HSP72 band lengths were significantly higher in the warm group. Correspondingly, HSP72 mRNA levels increased progressively in both groups, with significant difference between groups observed in biopsies at the reperfusion. Warm blood cardioplegia was associated with lower levels of CK-MB and troponin-T. Myocardial oxygen extraction and lactate release were higher during intermittent warm cardioplegia, indicating a more profound ischemic anaerobic metabolism in the warm group.

CONCLUSIONS

Intermittent warm blood cardioplegia induces an increased expression of HSP72 and it is associated with a better myocardial protection, by a mechanism involving a variant of the classical ischemic preconditioning model.

Simvastatin attenuates leucocyte-endothelial interactions after coronary revascularisation with cardiopulmonary bypass

OBJECTIVE

To investigate the effects of preoperative simvastatin treatment on leucocyte-endothelial interactions following coronary artery bypass surgery with cardiopulmonary bypass.

DESIGN

Double blind crossover study. Experiments on polymorphonuclear cells (neutrophils) were done at the end of cardiopulmonary bypass and one hour postoperatively. Endothelial P-selectin expression and neutrophil/endothelial adhesion were evaluated under either normoxic or hypoxic conditions.

SETTING

University hospital (tertiary referral centre).

PATIENTS

Three groups of patients undergoing coronary bypass surgery: 20 patients taking simvastatin for cholesterol control, 16 patients not responsive to simvastatin, and 20 controls.

MAIN OUTCOME MEASURES

Expression of neutrophil CD11b and endothelial P-selectin; adhesion of neutrophils to endothelium.

RESULTS

Cardiopulmonary bypass resulted in a significant increase in neutrophil CD11b expression in all groups. Similarly, the exposure of saphenous vein to hypoxia/reoxygenation induced an augmentation of endothelial P-selectin. However, both neutrophil CD11b expression and endothelial P-selectin exocytosis were less in the simvastatin groups than in the controls. Cardiopulmonary bypass and controlled hypoxia/reoxygenation stimulated neutrophil/endothelial adhesion, but the number of adhering cells was less in the simvastatin groups than in the controls, irrespective of the cholesterol concentration. Treatment of endothelial cells with L-NAME completely reversed the effects of simvastatin.

CONCLUSIONS

Pretreatment with simvastatin reduces neutrophil adhesion to the venous endothelium in patients undergoing coronary surgery, irrespective of its efficacy at lowering cholesterol concentration.

[Statins: from hypocholesteremic drugs to antiatherogenic agents]

Statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) are widely used for the treatment of hypercholesterolemia. They reduce LDL levels more than other lipid-lowering drugs. Moreover, they are effective in raising HDL and even in reducing triglyceride levels. Statins have an excellent tolerability and safety. Clinical trials in patients with and without ischemic heart disease and with and without high cholesterol levels have demonstrated that statins significantly reduce the relative risk of major coronary events and of total mortality. Other mechanisms independent of LDL lowering may play an important role in the clinical benefits conferred by these drugs and may broaden their therapeutic indications from lipid-lowering to antiatherogenic agents.

Left main coronary artery aneurysm: a case report and review of the literature

Left main coronary artery aneurysm is an uncommon feature of coronary artery disease in adults. We describe the case of a large aneurysm in a 58-year-old patient undergoing cardiac catheterization for effort angina and inducible myocardial ischemia. Specific considerations about the underlying causes and therapeutic options are discussed.

Early and long-term results of stenting of diffuse coronary artery disease

Diffuse coronary artery disease (CAD) is considered unfavorable for interventional procedures; however, the results of stenting of diffuse CAD have not been completely characterized. We performed stenting in 100 consecutive patients with diffuse CAD, defined as significant stenosis >20 mm (n = 59 patients), multiple significant stenoses in the same artery (n = 23 patients), or significant narrowing involving the whole length of the coronary artery (n = 18 patients). Angiographic success was achieved in 103 arteries (100%) and clinical success was obtained in all 100 patients. There were no deaths; no patient had stent closure, acute myocardial infarction, or required emergency coronary artery bypass surgery. All 100 patients had >6 months follow-up (mean 18 +/- 7 months, range 7 to 31); 77 (77%) remained asymptomatic, and 5 (5%) had acute myocardial infarction, of whom 2 died (2%). In-stent restenosis was observed in 12 patients (12%) and repeat angioplasty was performed in 10. Including those patients who underwent repeat angioplasty, 89 (89%) maintained clinical improvement and 95 (95%) were alive and free of bypass surgery during follow-up. Life-table analysis showed 86% freedom from death, myocardial infarction, and target lesion revascularization at 28 months. Thus, selected patients with diffuse CAD may be treated with satisfactory acute and long-term results by stent implantation.

Intravascular physiologic evaluation of the left anterior small thoracotomy operation: a novel approach to left anterior descending artery revascularization

BACKGROUND

Efficacy and long-term patency rate of the left internal mammary artery (LIMA) conduits for revascularization of the left anterior descending coronary artery (LAD) has been demonstrated, with improved results as compared to the saphenous vein graft operation. Novel approaches to LAD revascularization including the use of the left anterior small thoracotomy (LAST) operation with persistence of the intercostal arteries compared to the traditional LIMA operation have not been reported. This study evaluated flow characteristics of LAST operation.

METHODS

Phasic blood flow velocity in the proximal and distal arterial conduit segments was measured in 30 patients by intravascular Doppler flow wire after surgical revascularization of the LAD: 15 patients were revascularized by conventional operation using the LIMA (Group A), and 15 patients were submitted to the LAST operation (Group B). All patients underwent coronary angiography and ventriculography at 116 +/- 111 days after operation. Only angiographically normal grafts with normal left ventricular wall motion and coronary arteries free from significant distal stenosis were included for coronary flow velocity and reserve measurements.

RESULTS

The diastolic/systolic velocity ratio in the proximal portion of the internal mammary artery was similar in the two groups (Group A 0.8 +/- 0.2 vs Group B 0.7 +/- 0.3, p = NS). Distal diastolic/systolic velocity ratio in Group A (1.7 +/- 0.1) was higher than Group B (0.9 +/- 0.3, p < 0.001). There were no differences in basal average peak velocity or coronary flow reserve between the proximal and distal segments for either groups.

CONCLUSIONS

Although proximal phasic coronary flow patterns between the two groups were similar, distal diastolic/systolic velocity ratio was higher in the LIMA than in the LAST. This difference may be related to the persistence of the intercostal artery in the LAST operation. These data confirm the continued patency and similar functional flow patterns compared to the conventional LIMA operation, supporting further investigation and application of this novel approach to LAD revascularization.

Apoptosis in recent myocardial infarction

PURPOSE

Apoptosis is considered a common pathological feature in acute myocardial infarction (MI) and heart failure; however its role in the later phases post MI has not been characterized. The goal of our study was to investigate by pathological examination human hearts at 20 to 30 days post MI and identify signs of ongoing cell apoptosis.

MATERIALS AND METHODS

Two hearts were collected at autopsy from patients who died 20 to 30 days from the onset of MI (Cases 1 and 2). Gross anatomy and light microscopy examination of the hearts was performed to define the infarcted area and the infarct-related artery. The in situ end-labeling of DNA fragmentation (TUNEL) was performed to identify apoptotic cells and the apoptotic rate (AR) was calculated.

RESULTS

There were no signs of acute necrosis in any of the specimens examined. A high number of myocardiocyte were positive at TUNEL examination in specimens obtained at sites of infarction, mean AR = 44%, but not in specimens derived from the same patients at regions remote from the MI, AR = 0.

CONCLUSIONS

High grade apoptosis is present at sites of infarction and not in regions remote from the infarcted area in the later phases post MI. These data support persistent myocardiocyte loss and identify a possible explanation of progressive left ventricular dysfunction in the subacute phases of MI.

[Platelet glycoprotein IIB-IIIA receptor inhibitors in patients with ischemic heart disease]

Glycoprotein IIb-IIIa receptor inhibitors are the newest anti-platelets drugs currently used in patients with coronary artery disease. We examined mechanisms of their action and different pharmacokinetic and pharmacodynamic characteristics of the four glycoprotein IIb-IIIa antagonists evaluated in randomized, controlled and multicenter trials. We reviewed results of these trials in the settings of percutaneous revascularizations procedures or unstable coronary syndromes. Platelet glycoprotein IIb-IIIa receptor inhibitors reduced incidence of cardiac death and myocardial infarction during the short- and midterm, and benefit was greater in: a) patients undergoing coronary angioplasty with or without stent implantation, particularly in the presence of unstable angina, diabetes or complex and diffuse coronary artery disease; b) as a direct therapy of unstable coronary syndromes, particularly in patients with refractory angina, diabetes and elevated Troponin; more recently they have been used as adjuvant therapy in acute myocardial infarction. Infusion of these drugs was not associated with higher rates of major bleedings.

Gemcitabine-induced atrial fibrillation: a hitherto unreported manifestation of drug toxicity

BACKGROUND

Gemcitabine is an antimetabolic drug for solid tumors. Although its pharmacokinetics as well as its side-effects are well known, paroxysmal atrial fibrillation associated to the administration of this drug has not yet been described.

PATIENTS AND METHODS

We describe the case of a 78-year-old man with pancreatic adenocarcinoma who presented repeated paroxysmal atrial fibrillation episodes 18-24 hours after every gemcitabine infusion which resolved with antiarrhythmic drugs. This clinical history was positive for a remote brief episode of atrial fibrillation, which resolved spontaneously, and the patient had no predisposing factors for supraventricular arrhythmias (systemic hypertension, diabetes or coronary artery disease).

RESULTS

Cardiac work-up revealed only a mild mitral-valve prolapse and complete right bundle branch block. During the arrhythmia episodes no other precipitating factors were reported. The close temporal relationship of the arrhythmia to drug administration and the recurrence of arrhythmia upon rechallenge allowed to hypothesize an intrinsic pro-arrhythmic effect of gemcitabine or its metabolite 2',2'-difluorodeoxyuridine.

CONCLUSIONS

The occurrence of atrial fibrillation during the administration of gemcitabine may be considered as a cardiac arrhythmia drug-related toxicity. This side-effect of gemcitabine infusion is a previously unreported sign of drug toxicity; therefore, a high level of awareness to this problem is warranted when this drug is administered.

Vascular and haemostatic gene polymorphisms associated with non-fatal myocardial infarction: a critical review

The importance of genetics to the pathogenesis of myocardial infarction is suggested by the frequent familial clustering of premature disease. Yet, studies associating myocardial infarction with gene polymorphisms of vascular proteins (angiotensinogen, angiotensin converting enzyme, angiotensin II type 1 receptor, endothelial nitric oxide synthase) and haemostatic factors (fibrinogen, coagulation factors II, V, VII and XIII, plasminogen activator inhibitor-1, tissue-type plasminogen activator, platelet glycoproteins IIb/IIIa, Ia/IIa and Ib-IX-V, or methylenetetrahydrofolate reductase) have revealed conflicting results. This is hardly surprising, given: 1) the multigenic nature of myocardial infarction, whereby single polymorphisms are bound to play at best only a limited role in the global risk of disease; 2) the multiple pathogenetic mechanisms of infarction (e.g., atheromatous obstruction, plaque rupture, thrombosis, vasospasm), each of which is likely influenced by a number of genes and by several environmental factors. The simultaneous investigation of a set of polymorphisms--and of their interactions with environmental factors--in extremely homogeneous sets of patients should offer a better understanding of the contribution of specific genes to the risk of myocardial infarction.

[Remodelling of the radial artery graft 5 years after aortocoronary bypass intervention]

BACKGROUND

The radial artery (RA) is being employed as coronary artery bypass graft with good results, but when it is proximally anastomosed to the ascending aorta, undergoes substantial hemodynamic changes which could lead to significant graft intimal hyperplasia. The aim of this study was to investigate the evolution of RA graft morphology over time.

METHODS

We studied 20 patients with a perfectly patent RA graft at both 1 and 5 year angiography after coronary artery bypass graft.

RESULTS

Both RA graft and grafted coronary artery diameters, assessed by quantitative coronary angiography, significantly increased at 5 years, in comparison to 1 year angiography (2.08 +/- 0.45 vs 2.54 +/- 0.53 mm, +22%, p < 0.001 and 1.92 +/- 0.47 vs 2.18 +/- 0.41 mm, +13.3%, p < 0.001, respectively).

CONCLUSIONS

Hemodynamic changes following RA employment for coronary artery bypass graft stimulate a remodeling of RA graft itself and of the grafted coronary arteries. The progressive increase of diameters observed in RA grafts strongly argues against the development of flow-limiting graft intimal hyperplasia when RA is proximally anastomosed to the ascending aorta. Moreover, grafted coronary artery dilation suggests that hemorrheologic changes following coronary artery bypass graft could play a major role in the development of RA remodeling over time.

Directional coronary atherectomy: from therapeutic device to research tool in coronary artery disease

Directional coronary atherectomy (DCA) was introduced as a new percutaneous revascularization modality in 1990, and was initially applied to large vessels without tortuosity or calcification, with overall results including a 95% procedural success, 94% clinical success and 4.6% major complications (urgent bypass surgery in 3.8%, Q wave myocardial infarction in 1.7%, and hospital mortality in 0.3% of patients). In addition to its established efficacy for eccentric lesions, newer applications emerged such as treatment of saphenous vein grafts, thrombus-associated lesions, aorto-ostial lesions, failed or suboptional coronary angioplasty results, bifurcation lesions and use as a part of multi-vessel intervention. Comparative studies with coronary angioplasty such as CAVEAT I and II and CCAT showed better success rates with DCA vs coronary angioplasty, but failed to demonstrate benefit in restenosis rates. OARS and BOAT studies helped define optimal atherectomy techniques, which led to better acute angiographic results and to the "debulking plus stenting" concept. A spin-off of those clinical applications has been the opportunity to study the histology of tissue excised by DCA in vivo in different clinical settings. Such studies, investigating plaque ulceration, thrombosis and inflammation are reviewed, with special emphasis on new insights into unstable angina; the future of atherectomy research is also outlined with a categorization of various possible protocols to be applied utilizing coronary atherectomy specimens from live patients.

Improvement of myocardial ischemia by subclavian stent implantation in patients with internal mammary grafts: a case report and review of the literature

In patients with coronary bypass which utilizes left (LIMA) or right internal mammary artery (RIMA), recurrent ischemia is often due to stenosis of the distal anastomoses of the grafts. However, occasionally, ischemia may be due to extracoronary causes, such as subclavian disease proximal to the internal mammary artery origins. This case report describes such clinical situation emphasizing the need for careful patient evaluation, and discusses therapeutic interventional options, in particular, safety and effectiveness of self expanding subclavian stent implantation. A review of the literature is also presented.

Coronary stenting in patients with situs viscerum inversus

Atherosclerotic coronary disease may develop even in patients with complex cardiovascular anomalies who reach adult life. Coronary revascularization (surgical or interventional) may present potential difficulties related to the unusual anatomy. We describe two cases of situs viscerum inversus who underwent cardiac catheterization and angiography as adults because of ingravescent angina. The study identified the cardiac relations and connections, and diagnosed severe coronary disease that was successfully treated with coronary angioplasty and stent implantation. The implications of performing such procedures in patients with similar cardiac anomalies are discussed.

Stenting of a stenotic radial artery coronary graft: a new therapeutic scenario in coronary artery disease

With the increasing application of arterial coronary revascularization, a number of patients may develop arterial graft obstructive disease. In addition, the predominantly muscular structure of the radial artery wall may predispose radial artery coronary grafts to spasm. For the first time, we describe a case of stenting of a stenotic free radial artery graft and discuss the technical and pathophysiological aspects of the procedure.

[The radial artery in coronary surgery: the midterm clinical and angiographic results and the variation in vasoreactivity over time]

OBJECTIVE

To evaluate the mid-term angiographic results of radial artery grafts used for myocardial revascularization.

METHODS

The first 68 consecutive surviving patients who received a radial artery graft proximally anastomosed to the aorta at our institution were restudied in a five-year follow-up (mean 59 +/- 6.5 months); 48 of these patients had already undergone an early angiographic examination. The response of the radial artery to the endovascular infusion of serotonin was evaluated one and five years after surgery and the mid-term status of the radial artery grafts was correlated with the degree of stenosis of the target vessel and with the Ca(++)-channel-blocker therapy.

RESULTS

The patency and perfect patency rates of the radial artery five years after the operation were 91.9 and 87.0% respectively. All radial artery grafts that were patent early after surgery remained patent at mid-term follow-up and in seven patients early parietal irregularities disappeared after five years. The early propensity to graft spasm after serotonin challenge decreased markedly at mid-term follow-up. The continued use of Ca(++)-antagonists after the first postoperative year did not affect the status of the radial artery graft, whereas the severity of target-vessel stenosis markedly influenced the angiographic results.

CONCLUSIONS

The mid-term angiographic results of RA grafts used for myocardial revascularization are excellent. A correct surgical indication is essential, whereas continued therapy with Ca(++)-antagonists after the first year does not influence the mid-term angiographic results.