Comprehensive mitral valve prolapse assessment by cardiovascular MRI.

Mitral valve (MV) prolapse (MVP) is a not fully understood common MV disorder. The development of sophisticated cardiovascular magnetic resonance imaging (CMRI) sequences over the last decades has allowed a more detailed assessment and provided better understanding of the pathophysiology of MVP to guide management, interventions, and risk stratification of patients affected. This review provides an overview of the most recent insights about this multifaceted pathology, particularly regarding the emerging concepts of mitral annular disjunction (MAD), and risk of arrhythmia and sudden death associated with myocardial fibrosis. We describe the emerging role of CMRI in both diagnosis and, more importantly, risk assessment of this disease, aiming to provide a comprehensive protocol for the assessment of MVP, which could represent a practical guide to clinicians and MRI practitioners working in the field.

Galectin-9 suppresses B cell receptor signaling and is regulated by I-branching of N-glycans.

Leukocytes are coated with a layer of heterogeneous carbohydrates (glycans) that modulate immune function, in part by governing specific interactions with glycan-binding proteins (lectins). Although nearly all membrane proteins bear glycans, the identity and function of most of these sugars on leukocytes remain unexplored. Here, we characterize the N-glycan repertoire (N-glycome) of human tonsillar B cells. We observe that naive and memory B cells express an N-glycan repertoire conferring strong binding to the immunoregulatory lectin galectin-9 (Gal-9). Germinal center B cells, by contrast, show sharply diminished binding to Gal-9 due to upregulation of I-branched N-glycans, catalyzed by the ß1,6-N-acetylglucosaminyltransferase GCNT2. Functionally, we find that Gal-9 is autologously produced by naive B cells, binds CD45, suppresses calcium signaling via a Lyn-CD22-SHP-1 dependent mechanism, and blunts B cell activation. Thus, our findings suggest Gal-9 intrinsically regulates B cell activation and may differentially modulate BCR signaling at steady state and within germinal centers.

IL-6 is associated to IGF-1Ec upregulation and Ec peptide secretion, from prostate tumors.

BACKGROUND: Ec peptide (PEc), resulting from the proteolytic cleavage of the IGF-1Ec isoform, is involved in prostate cancer progression and metastasis, whereas in muscle tissue, it is associated with the mobilization of satellite cells prior to repair. Our aim is to determine the physiological conditions associated to the IGF-1Ec upregulation and PEc secretion in prostate tumors, as well as, the effect of tumor PEc on tumor repair. METHODS: IGF-1 (mature and isoforms) expression was examined by qRT-PCR, both in prostate cancer cells co-incubated with cells of the immune response (IR) and in tumors. PEc secretion was determined by Multiple Reaction Monitoring. The effect of PEc, on mesenchymal stem cell (MSC) mobilization and repair, was examined using migration and invasion assays, FISH and immunohistochemistry (IHC). The JAK/STAT signaling pathway leading to the IGF1-Ec expression was examined by western blot analysis. Determination of the expression and localization of IL-6 and IGF-1Ec in prostate tumors was examined by qRT-PCR and by IHC. RESULTS: We documented that IL-6 secreted by IR cells activates the JAK2 and STAT3 pathway through IL-6 receptor in cancer cells, leading to the IGF-1Ec upregulation and PEc secretion, as well as to the IL-6 expression and secretion. The resulting PEc, apart from its oncogenic role, also mobilizes MSCs towards the tumor, thus promoting tumor repair. CONCLUSIONS: IL-6 leads to the PEc secretion from prostate cancer cells. Apart from its oncogenic role, PEc is also involved in the mobilization of MSCs resulting in tumor repair.

From the BMI paradox to the obesity paradox: the obesity-mortality association in coronary heart disease.

Despite a strong association between body weight and mortality in the general population, clinical evidence suggests better clinical outcome of overweight or obese individuals with established coronary heart disease. This finding has been termed the 'obesity paradox', but its existence remains a point of debate, because it is mostly observed when body mass index (BMI) is used to define obesity. Inherent limitations of BMI as an index of adiposity, as well as methodological biases and the presence of confounding factors, may account for the observed findings of clinical studies. In this review, our aim is to present the data that support the presence of a BMI paradox in coronary heart disease and then explore whether next to a BMI paradox a true obesity paradox exists as well. We conclude by attempting to link the obesity paradox notion to available translational research data supporting a 'healthy', protective adipose tissue phenotype. © 2016 World Obesity.

Effects of atorvastatin on endothelial function and the expression of proinflammatory cytokines and adhesion molecules in young subjects with successfully repaired coarctation of aorta.

OBJECTIVE: To investigate the effects of atorvastatin on endothelial function and low-grade systemic inflammation in subjects with successful surgery for aortic coarctation repair (SCR). DESIGN: Open-label study. SETTING: Outpatients visiting the adult congenital heart disease department of our hospital. PATIENTS: 34 young people with SCR. INTERVENTIONS: Patients with SCR received atorvastatin 10 mg/day (n=17) or no treatment (n=17) for 4 weeks. At baseline and at 4 weeks, endothelial function was assessed by flow-mediated dilatation (FMD) of the right brachial artery, and blood samples were obtained. Serum levels of interleukin (IL) 1b, IL-6 and soluble vascular cell adhesion molecule-1 (sVCAM-1) were determined by ELISA. MAIN OUTCOME MEASURES: Effects of treatment on FMD and serum levels of IL-1b, IL-6 and sVCAM-1. RESULTS: FMD in the atorvastatin group was significantly improved after 4 weeks (from 6.46±0.95% to 11.24±1.38%, p<0.01), while remaining unchanged in the control group (from 6.74±0.58% to 6.95±0.53%, p=NS). Even though atorvastatin had no effect on serum IL-6 levels (0.62 (0.37-0.88) pg/ml to 0.53 (0.28-0.73) pg/ml, p=NS), it significantly reduced circulating levels of IL-1b (from 1.17 (0.92-1.77) pg/ml to 1.02 (0.75-1.55) pg/ml, p<0.05) and sVCAM-1 (from 883.4 (660.3-1093.1) ng/ml to 801.4 (566.7-1030.2) ng/ml, p<0.05). No changes were seen in serum levels of IL-6, IL-1b and sVCAM-1 in the control group after 4 weeks compared with baseline (p=NS for all). CONCLUSIONS: Atorvastatin treatment for 4 weeks in subjects with SCR significantly improved endothelial function and suppressed systemic inflammatory status by decreasing circulating levels of IL-1b and sVCAM-1.

Exercise duration as a determinant of vascular function and antioxidant balance in patients with coronary artery disease.

BACKGROUND: Exercise improves the clinical outcome of patients with coronary artery disease (CAD); however, the ideal exercise duration for each patient remains unclear. OBJECTIVE: To investigate the effects of exercise duration on arterial elastic properties and antioxidant/pro-oxidant mechanisms in patients with CAD. DESIGN, SETTING, PATIENTS, INTERVENTIONS: Sixty male patients with CAD were randomised into two groups, and underwent exercise for 30 min or 60 min in a crossover design with 2 weeks' wash-out period. In all participants aortic and radial blood pressures (BP) and arterial elastic properties (augmentation index (AIx)/pulse wave velocity (PWV)) were determined at baseline and 24 h after exercise. Plasma malonyldialdehyde (MDA) and superoxide dismutase (SOD)1 and SOD2 levels were also measured. RESULTS: Exercise had no effect on aortic and radial BP (p=NS for all). Walking for 30 min improved AIx (from 33.79 ± 0.91% to 31.73 ± 0.86%, p<0.001) and PWV (from 9.26 ± 0.95 m/s to 9.06 ± 0.21 m/s, p<0.001), while exercise for 60 min had adverse effects on vascular stiffness (for AIx: from 33.37 ± 0.93% to 33.73 ± 1.05%, p=NS and for PWV: from 9.25 ± 0.19 m/s to 9.37 ± 0.21 m/s, p < 0.05 mainly in older patients). Exercise for 60 min was associated with a significant 20% increase in MDA levels (p<0.05). Exercise had no effects on SOD1 levels, however it significantly increased SOD2 levels after 30 min (from 2.26 ± 0.22 ng/mL to 2.36 ± 0.18 ng/mL, p < 0.05) but not after 60 min (p=NS). Conclusion Shorter exercise duration was associated with favourable antioxidant and vascular effects, while longer exercise blunted these beneficial effects and was accompanied by adverse effects on vascular function, mainly in older coronary patients. Further studies are required to explore the hypothesis that a more individualised approach to the selection of the appropriate exercise programme should be considered for patients with CAD.

Adiponectin: from obesity to cardiovascular disease.

Adiponectin is an adipokine whose biosynthesis is deranged in obesity and diabetes mellitus, predisposing to atherosclerosis. Evidence suggests that adiponectin has anti-atherogenic properties by improving endothelial function and having anti-inflammatory effects in the vascular wall. In addition, adiponectin modifies vascular intracellular redox signalling and exerts indirect antioxidant effects on human myocardium. However, its clinical role in cardiovascular disease is obscure. Adiponectin's positive prognostic value in coronary artery disease had been widely supported over the last years, but this view has been questioned recently. High adiponectin levels are paradoxically associated with poorer prognosis in heart failure syndrome. These controversial findings seem surprising as adiponectin has been viewed overall as an anti-atherogenic molecule. Therefore, any certain conclusion about adiponectin's role in cardiovascular disease seems premature. Despite the rapidly accumulating literature on this adipokine, it is still unclear whether adiponectin is a key mediator or a bystander in cardiovascular disease. It is still uncertain whether adiponectin levels have any clinical significance for risk stratification in cardiovascular disease or they just reflect the activation of complex and opposing underlying mechanisms. Circulating adiponectin levels should be interpreted with caution, as they may have completely different prognostic value, depending on the underlying disease state.

A fatal case of cutaneous zygomycosis in a patient with severe metabolic acidosis.

We present a case of cutaneous zygomycosis in a patient with an ureteroileostomy and severe metabolic acidosis, but without diabetes. The patient died despite multiple aggressive surgical interventions and antifungal therapy with liposomal amphotericin B. Ureteroileostomy-related acidosis can be a predisposing factor for zygomycosis. Metabolic acidosis can have a role in the severity of cutaneous disease.

Synchronous primary cancers in a woman with scleroderma: a case report.

BACKGROUND: Scleroderma is a chronic, multisystem, autoimmune disease. Previous studies have shown an increased risk of malignancy in scleroderma; the most common cancers were lung cancer and breast cancer. CASE: The patient, a 43-year-old nulliparous premenopausal Greek woman with scleroderma, presented with a history of abdominal pain and atypical vaginal bleeding. She underwent total hysterectomy with bilateral salpingo-oophorectomy, total omentectomy, appendectomy and pelvic lymph node dissection. The histopathology revealed synchronous primary cancers of the endometrium and left ovary. She underwent postoperative chemotherapy and remains well without evidence of disease 25 months after surgery. CONCLUSION: Synchronous primary cancers of the endometrium and ovary are relatively uncommon in the general population. Only a few cases of cancer of the female genital tract in women with scleroderma have been reported in the English literature.

Cardiac hypertrophy and how it may break an athlete's heart--the Cypriot case.

AIMS: This is a case report of an athlete whose professional football career was transiently terminated because of the presumed diagnosis of hypertrophic cardiomyopathy. METHODS AND RESULTS: The diagnosis was based on electrocardiographic repolarisation changes. The ECGs, treadmill exercise tests (Bruce protocol) and echo examinations at the time of his active training and several years after termination of his professional career are discussed. No hypertrophic cardiomyopathy was documented by ultrasound examination. CONCLUSIONS: The distinction between physiological athlete's heart and pathological conditions has critical implications for professional athletes. Criteria and guidelines for screening of athletes in competitive sports are recommended.

Comparative analysis of enzymatically digested kappa-carrageenans, using liquid chromatography on ion-exchange and porous graphitic carbon columns coupled to an evaporative light scattering detector.

Enzymatically digested kappa (A-G4S)-carrageenans, apart from their biological activities in plants, could be used as 'model' molecules to elucidate potential problems in nuclear magnetic resonance spectroscopy of carrageenans. Thus, oligosaccharides obtained from kappa-carrageenan by enzymatic digestion using kappa-carrageenase have been separated on silica and polymeric based ion-exchange and porous graphitic carbon (PGC) columns, coupled to an evaporative light scattering detector. Oligomers were separated on ion-exchange columns using a gradient of ammonium acetate as a developing ion, while analysis on PGC column presented an additional adjacent peak next to each main one, using a gradient of ammonium acetate in water/acetonitrile as a mobile phase. The phenomenon can be attributed to different retention mechanisms that govern the PGC surface. Furthermore, it has been demonstrated that acetonitrile can regulate the selectivity between the peaks raising hopes for preparative chromatography.

Characterisation of iota-carrageenans oligosaccharides with high-performance liquid chromatography coupled with evaporative light scattering detection.

Enzymatically digested oligo-iota-carrageenans were separated with liquid chromatography, coupled to evaporative light scattering detection. As expected, compared to oligo-kappa-carrageenans, the additional sulphate group in the neocarrabiose unit of iota-carrageenans significantly modified the separation mechanisms on ion-exchange chromatography, porous graphitic carbon and ion-pair chromatography. The oligomers were then isolated and characterised off-line with electrospray ionisation mass spectrometry in positive-ion mode. The tetrasaccharide, hexasaccharide and octasaccharide that were identified were associated with protonated heptylamine molecules whose number depended on the number of sulphate groups.

Study of the attachment of Na+ on glucose and on some of its methylated derivatives.

The mechanism of attachment of Na(+) on glucose, methyl-alpha-D-glucose, methyl-beta-D-glucose, 3-O-methylglucose, tetra-O-methylglucose, and also on galactose and methyl-beta-D-galactose, was studied. For this we measured the ion yields for the complex [sugar-Na(+)] formed by ionisation by matrix-assisted laser desorption/ionisation (MALDI) and ionspray. These data were compared with the relative volatilities and hydrophobicities of the sugars, measured by evaporative light scattering and reversed-phase liquid chromatography, respectively. Some formation enthalpies for the complexes [sugar-Na(+)], starting from the sugar and the cation, were obtained by ab initio calculations. No simple correlations could be observed between the ion yields and the parameters studied, so that the cationisation mechanism of the sugars remains unclear.

Experience with predeposition of autologous blood in elective orthopaedic and plastic surgery: the role of oral iron medication.

The risk of transmission of transfusion-associated infections, mainly AIDS, led to the increased use of autologous transfusion by four methods: predeposition of autologous blood, haemodilution, intraoperative and postoperative blood salvage. We started a program of autologous predeposition at blood transfusion centre of Saint Andrews General Hospital of Patras in co-operation with orthopaedic and plastic surgery in 1992. To date, 617 autologous units have been collected from 257 patients undergoing various operations. Our protocol was as follows: the minimum Hb value before each donation was 12 g/dl, body weight over 50 kg, age 18-70 years and 8-10 day intervals between donations. The exclusion criteria were anaemia, evidence of blood loss, renal disease, chronic and acute inflammatory or malignant disorders, pregnancy and lactation. We chose 40 patients with haemoglobin values of 13-15 g/dl and ferritin levels > 50 ng/ml, who gave three autologous units. They were separated in two groups of twenty patients. Those in group 1 received 300 mg of elemental iron in three daily oral doses, while the others in group 2 received no iron medication. We studied haematologic variables, reticulocytes and ferritin levels in both groups before each autologous donation. We also studied the possible complications and their incidence in patients over 60 years old. According to our results, haematologic variables such as Hb, mean corpuscular Hb (MCH), mean corpuscular volume (MCV) and reticulocytes were not influenced by oral iron therapy. We observed a slight increase in MCV in both study groups which means the production of larger red blood cells. We also noticed a higher decrease of ferritin in patients with no iron therapy, but without a fall of ferritin levels under the normal values. We conclude that oral iron therapy in non-iron deficient patients undergoing a moderate program of three autologous units is not necessary. In addition, autologous blood donation is also feasible in patients over 60 years old without severe complications.

Thallium-201 for detection of myocardial viability: comparison of early postexercise reinjection and imaging with 4 and 18-24 hours redistribution imaging.

To evaluate the efficacy of an early 201Tl reinjection and imaging protocol for reducing the need for conventional 4-hour or optimal 24-hour redistribution imaging (RI) and detecting of myocardial viability, we compared the results of early postexercise Tl reinjection and imaging with those of 4- and 24-hour RI in 74 consecutive patients aged 55 +/- 9 years (mean +/- SD) who were assessed for myocardial ischemia. One millicurie of Tl was injected promptly after completion of the initial postexercise imaging (PEX) and three additional sets of images were acquired 1, 4 and 18-24 h later. A total of 2,368 segments were evaluated. On PEX, 390 (17%) segments showed defects, of which 287 (74%) showed enhanced Tl uptake at 1-hour RI; 89 (23%) did not change and 14 (4%) showed reverse redistribution. Of the 103 persistent defects, only 27 (7%) showed further fill-in of Tl; 62 (16%) segments showed reverse redistribution at 4-hour RI while at 18- to 24-hour RI 17 (4%) and 47 (12%) segments showed further fill-in of Tl and reverse redistribution, respectively. Finally, after analysis of 4- and 18- to 24-hour RI, the diagnosis changed from myocardial necrosis to ischemia in only 2 (3%) patients. In conclusion, these results suggest that by eliminating the need for an additional delayed set of images for detection of myocardial viability, this protocol reduces the total investigation procedure, is more convenient for the patient, increases patient turnover and expedites the decision-making process.

Early postexercise thallium-201 reinjection after sublingual nitroglycerin augmentation: effects on detection of myocardial ischemia and/or viability.

BACKGROUND: Thallium-201 (201Tl) reinjection after conventional redistribution imaging is a standard procedure, resulting in enhanced 201Tl redistribution which is compatible with viable myocardium. Although this method significantly improves identification of viable myocardium, it increases the investigation time by approximately 1 h. Thus, this technique is suboptimal from the standpoint of patient convenience, since its routine performance may be impractical in a high-volume nuclear medicine laboratory. HYPOTHESIS: This study was undertaken to evaluate the efficacy of an early 201Tl reinjection and imaging protocol in combination with sublingual nitroglycerin, to detect myocardial ischemia and/or viability, and to reduce the need for conventional (4 h) redistribution imaging. MATERIALS AND METHODS: In this study, 62 consecutive coronary patients, referred for the detection of possible myocardial ischemia and/or viability, were involved (mean age 55 years, range 41-70). Of those, 50 had previous angina attacks, with 42 having a history of previous myocardial infarction; 10 patients had coronary artery bypass grafting; and the remaining 2 had atypical chest pain. Immediately after the completion of the initial postexer-cise imaging, 0.3 mg sublingual nitroglycerin followed by the reinjection of 1 m Ci of 201Tl were administered, and two further sets of images were acquired 1 h and 4 h later. RESULTS: In each set of images, a total of 496 segments were analyzed. On postexercise imaging, 305 (61%) segments demonstrated defects of which 198 (65%) showed enhanced thallium uptake, 97 (32%) did not change, and 10 (3%) showed reverse redistribution on 1 h reinjection imaging (IRI). Of the 97 persistent defects, only 17 (6%) showed fill-in of 201Tl on 4 h redistribution imaging (CRI), while 12 (4%) segments showed reverse redistribution. On the other hand, after analyzing the 62 patients of the 1 h IRI, 17 (27%) remained unchanged while in only 1 patient (6%) of 17 the diagnosis changed from myocardial necrosis to ischemia after analysis of the 4 h CRI. CONCLUSION: These results indicate that early postexercise reinjection of 201Tl in combination with sublingual nitroglycerin followed by 1 h image acquisition may prove useful for a comprehensive and convenient assessment of myocardial ischemia and/or viability.

Familial discrete subaortic stenosis.

Discrete subaortic stenosis (DSS) accounts for 8 to 20% of all cases of congenital left ventricular outflow tract obstruction. There have been few scattered reports of left ventricular obstructive lesions occurring in immediate family members of patients with DSS. This is a report of four cases of DSS in one family: one brother with a fibrous ring, and two sisters and the son of one of the sisters with a fibrous membrane. The occurrence of multiple cases of DSS in this family suggests an autosomal dominant mode of inheritance.

Sinus node dysfunction in acute inferior myocardial infarction. Role of sinus node artery and clinical course in patients with one-vessel coronary artery disease.

To determine the role of the sinus node artery and the clinical course in postmyocardial infarction sinus node dysfunction, 27 patients with acute inferior myocardial infarction and single-vessel coronary artery disease were studied. In 13 patients (group 1) the infarct-related coronary artery was occluded proximally and in 14 (group 2) distally to the site of origin of the sinus node artery. At electrophysiology, performed 10 +/- 3 days from the acute event, basal and intrinsic heart rate were lower in group 1 compared to group 2 patients (54 +/- 4.8 vs. 69 +/- 7 beats/min, p = 0.001, and 66 +/- 7 vs. 76 +/- 8 beats/min, p = 0.006, respectively) while basal and intrinsic corrected sinus node recovery times were prolonged in group 1 compared to group 2 patients (585 +/- 49.3 vs. 324 +/- 61.3 ms, p = 0.0001, and 601 +/- 39.1 vs. 335 +/- 73 ms, p = 0.0001). During a 6-month follow-up no episodes of dizziness, syncope or angina were reported. Moreover, at the end of follow-up resting heart rate (70 +/- 11 vs. 73 +/- 7 beats/min, nonsignificant), maximal exercise heart rate (166 +/- 19 vs. 170 +/- 23 beats/min, nonsignificant), and exercise time (491 +/- 120 vs. 480 +/- 155 s, nonsignificant) were similar between the two groups and no exercise-induced ischemic ST segment depression was observed. Sinus node dysfunction in patients with inferior myocardial infarction and one-vessel disease is related to the occlusion of the infarct-related coronary artery proximal to the site of origin of the sinus node artery and is not associated with increased cardiovascular morbidity in the first 6 months from the acute event.

Effects of high-frequency electromagnetic fields on human lymphocytes in vitro.

Human peripheral lymphocytes were incubated in the presence of high-frequency electromagnetic fields of 380, 900 and 1800 MHz. The measured endpoints were cell cycle progression and the frequencies of sister-chromatid exchanges. No differences between treated and control cultures could be found.

Captopril adjuvant therapy to beta-blockers and nitrates improves post-myocardial infarction left ventricular performance.

A growing body of data support the beneficial effects of angiotensin-converting enzyme inhibitors in the prevention of cardiac enlargement and improvement of left ventricular function in patients with acute myocardial infarction. However, very little information exists about the direct effect of increased afterload on cardiac performance in these patients and the possible favourable effects of angiotensin-converting enzyme inhibitors as adjunctive treatment to thrombolysis, beta-blockers and nitrates. We have, therefore, studied the effects of captopril as adjuvant therapy to thrombolysis, beta-blockers and nitrates (standard therapy) on left ventricular performance in 77 consecutive patients with uncomplicated Q-wave acute myocardial infarction, by the measurement of the pre-ejection period/left ventricular ejection time ratio before and after (0.25-0.50 mg) phenylephrine administration on the 4th and 30th post-infarction days. Patients were randomized on day 4 either to continue standard therapy alone (group 1, 35 patients) or to receive oral captopril therapy (12.5 mg t.i.d.) in addition to standard therapy (group 2, 42 patients) in a double-blind parallel study. Among the patients of group 1 there was a significant deterioration of left ventricular function after phenylephrine administration. This was shown by an increase of pre-ejection period/left ventricular ejection time ratio only in the subset of patients with ejection fraction < 40%, as measured by contrast ventriculography, on both the 4th and 30th post-infarction days changing from 0.435 +/- 0.070 to 0.528 +/- 0.101, P < 0.01 and from 0.404 +/- 0.098 to 0.515 +/- 0.092, P < 0.02, respectively. In contrast there were no significant changes in patients with ejection fraction > or = 40%. Among patients of group 2, phenylephrine administration induced a significant increase, only on the 4th day, in pre-ejection period/left ventricular ejection time ratio only in the subset of patients with ejection fraction < 40% changing from 0.410 +/- 0.107 to 0.535 +/- 0.102, P < 0.01. In the remaining patients with ejection fraction > or = 40% there were no significant changes on either the 4th or 30th post-infarction days. Furthermore, a significant improvement was observed after phenylephrine administration in the pre-ejection period/left ventricular ejection time ratio between the 4th and 30th post-infarction days, which changed from 0.535 +/- 0.102 on day 4 to 0.368 +/- 0.052 on day 30 (P < 0.004). Also, a four-way ANOVA detected a significant reduction of heart rate in patients with ejection fraction < 40% from day 4 to day 30. The results indicate that: (1) the response of pre-ejection period/left ventricular ejection time ratio after increasing afterload may be a useful non-invasive method for the detection of left ventricular dysfunction in myocardial infarction patients; and (2) captopril adjuvant therapy as compared to thrombolysis, beta-blockers and nitrates alone, after phenylephrine administration, improves the left ventricular performance response in asymptomatic Q-wave post-infarction patients and beneficially affects heart rate. This effect is most pronounced in patients with ejection fraction < 40% whereas those with ejection fraction > or = 40% do not obtain clear benefit.