Rest perfusion abnormalities in hypertrophic cardiomyopathy: correlation with myocardial fibrosis and risk factors for sudden cardiac death.

AIM: To measure the prevalence of abnormal rest perfusion in a population of consecutive patients with known hypertrophic cardiomyopathy (HCM) referred for cardiovascular MRI (CMR), and to assess any associations between abnormal rest perfusion and the presence, pattern, and severity of myocardial scar and the presence of risk factors for sudden death. MATERIALS AND METHODS: Eighty consecutive patients with known HCM referred for CMR underwent functional imaging, rest first-pass perfusion, and late gadolinium enhancement (LGE). RESULTS: Thirty percent of the patients had abnormal rest perfusion, all of them corresponding to areas of mid-myocardial LGE and to a higher degree of segmental hypertrophy. Rest perfusion abnormalities correlated with more extensive and confluent LGE. The subgroup of patients with myocardial fibrosis and rest perfusion abnormalities (fibrosis+/perfusion+) had more than twice the incidence of episodes of non-sustained ventricular tachycardia on Holter monitoring in comparison to patients with myocardial fibrosis and normal rest perfusion (fibrosis+/perfusion-) and patients with no fibrosis and normal rest perfusion (fibrosis-/perfusion-). CONCLUSIONS: First-pass perfusion CMR identifies abnormal rest perfusion in a significant proportion of patients with HCM. These abnormalities are associated with the presence and distribution of myocardial scar and the degree of hypertrophy. Rest perfusion abnormalities identify patients with increased incidence of episodes of non-sustained ventricular tachycardia on Holter monitoring, independently from the presence of myocardial fibrosis.

Metalloproteinases 2 and 9 are increased in plasma of patients with heart failure.

BACKGROUND: Progression of heart failure is associated with interstitial changes in the heart and in areas distant from the heart. Enhanced expression of metalloproteinases 2 and 9 and of metalloproteinases tissue inhibitors 1 and 2 have been found in ventricular tissue of patients with heart failure. Our aim was to determine whether increased activity of metalloproteinase-2, metalloproteinase-9 and of metalloproteinases tissue inhibitor-1 and metalloproteinases tissue inhibitor-2 were also present in plasma of patients with heart failure. DESIGN: Levels of metalloproteinase-2, metalloproteinase-9 and of metalloproteinase tissue inhibitor-1 and metalloproteinases tissue inhibitor-2 were measured in venous blood of 51 patients with heart failure, and were compared with levels of 52 control subjects. Samples collected from patients and control subjects were assayed for gelatinolytic activity (zymography) and for protein levels. RESULTS: Compared with the control subjects, the patients with heart failure had a significant increase in activity levels (mean +/- SE, ng mL(-1)) of prometalloproteinase-9 (95.1+/-11.2 and 38.9+/-4.5*), activ. metalloproteinase-9 (18.4+/-2.5 and 10.9+/-1.3*), and of prometalloproteinase-2 (571.4+/-26.1 and 456.8+/-21.1*) (respectively: patients and control subjects; *P<0.05). Metalloproteinases tissue inhibitor-1, but not metalloproteinases tissue inhibitor-2 protein values were higher in the patients. Among the patients, clinical status and New York Heart Association (NYHA) class did not correlate with the metalloproteinase concentrations. Positive correlations with left ventricular volumes, and negative correlations with lipid values were obtained for prometalloproteinase-2; positive correlations with total number of white cells and neutrophils were obtained for prometalloproteinase-9; and positive correlations with lactate dehydrogenase, serum fibrinogen, aspartate transaminases were found for activ. metalloproteinase-9. CONCLUSIONS: Regardless of the clinical phase of heart failure, elevated levels of activity and of circulating metalloproteinase protein levels suggest the presence of persistent extracellular remodeling in patients with heart failure.

High doses of atorvastatin do not affect activity of prothrombinase in patients with acute coronary syndromes.

Membrane-dependent coagulation processes play a key role in acute coronary syndromes (ACS), where the generation of thrombin depends on the complex of activated factors X and V (prothrombinase complex) assembled on activated platelets. The aim of the present study was to evaluate prothrombinase activity in patients with ACS and to examine the effect of treatment with 80 mg/day atorvastatin on prothrombinase activity. Blood samples were obtained at admission from 22 patients with ACS, and then again at 2 weeks and at 16 weeks after double-blind randomization to either placebo or atorvastatin. Prothrombinase activity was evaluated by measuring the generation of thrombin by in vitro reconstructed thrombi, and also by measuring plasma levels of prothrombin fragment F1 + 2. Twenty age-matched subjects with stable angina and 11 without coronary disease were used as controls. At admission, prothrombinase activity and F1 + 2 were significantly higher in ACS patients than in controls. Prothrombinase activity was still high at 2 weeks while it returned to normal levels at 16 weeks. F1 + 2 remained high both at 2 and at 16 weeks. Our data indicate that prothrombinase activity is high in patients with ACS, and that it is not affected by high-dose atorvastatin.

Maximal endothelial tissue plasminogen activator release is not impaired in patients with acute coronary syndromes before heparin treatment.

Procoagulant and fibrinolytic disturbances are described in patients with acute coronary syndromes (ACS), but whether defective maximal tissue plasminogen activator (t-PA) release from the endothelium is also present is still controversial. Previous studies did not take into consideration the contribution of heparin, which strongly affects fibrinolysis. Accordingly, in this study, we measured maximal t-PA release in patients with ACS before, during, and after heparin treatment. Maximal t-PA release was measured by the venous occlusion test in 38 hospitalized patients with confirmed ACS (18 acute myocardial infarctions and 20 unstable anginas) before starting heparin, during heparin treatment, and 4 and 12 h after discontinuation. Plasma plasminogen activator inhibitor type 1 (PAI-1), D-dimer and prothrombin fragment F1 + 2 were also measured. Eighteen age-matched subjects with no evidence of coronary disease were used as controls. At admission, patients showed significantly higher plasma levels of t-PA, PAI-1, and F1 + 2 than controls. Before heparin, maximal t-PA release was similar in patients and controls. Heparin treatment was associated with a significant increase of plasma t-PA, while it did not affect maximal t-PA release. Coagulative and fibrinolytic disturbances are present in patients with ACS, but these do not include maximal t-PA release. Among our patients, maximal t-PA release appears stable over time and is not affected by heparin treatment.

N-acetyl-cysteine reduces neointimal thickening and procoagulant activity after balloon-induced injury in abdominal aortae of New Zealand white rabbits.

BACKGROUND: Procoagulant activity and oxidative stress generated by balloon injury to normal vessels promote the migration of medial smooth muscle cells and their proliferation in the intima. We hypothesised that administering levo N-acetyl-cysteine (NAC) i.v. at the time of injury, and s.c. before and after injury would reduce neointimal formation 4 weeks later and would regulate procoagulant activity in vessels with neointima undergoing ballooning a second time. METHODS AND RESULTS: at the time of injury rabbits received: NAC, unfractionated heparin (HEP) or both (NAC + HEP). Neointimal thickening at 28 days, calculated as the ratio between the intimal and medial area, was attenuated after NAC, HEP and NAC+HEP by 39%, 30% and 47% respectively when compared to untreated injured animals (CONTROLS) (p <0.05). At 28 days, bound thrombin activity and platelet adhesion 1 h after a repeated balloon injury decreased in animals receiving NAC, HEP and NAC+HEP bv 54%, 63% and 64% for thrombin activity (p <0.05 vs CONTROLS), and by 56%, 66% and 75% respectively for 111Indium-platelet deposition (p <0.05 vs CONTROLS). CONCLUSIONS: NAC in-vivo was effective in reducing neointimal thickening and procoagulant response after balloon injury.

Sulfonylurea treatment of type 2 diabetic patients does not reduce the vasodilator response to ischemia.

OBJECTIVE: Sulfonylureas block the activation of vascular potassium-dependent ATP channels and impair the vasodilating response to ischcmia in nondiabetic individuals, but it is not know whether this occurs in type 2 diabetic patients under chronic treatment with these drugs. Glimepiride, a new sulfonylurea, apparently has no cardiovascular interactions. The aim of our study was to compare the effect of the widely used compound glibenclamide, the pancreas-specific glimepiride, and diet treatment alone on brachial artery response to acute forearm ischemia. RESEARCH DESIGN AND METHODS: Brachial artery examination was performed by a high-resolution ultrasound technique on 20 type 2 diabetic patients aged mean +/- SD) 67 +/- 2 years and on 18 nondiabetic patients matched for age, hypertension, and dislipidemia. Diabetic subjects underwent three separate evaluations at the end of each 8-week treatment period, during which they received glibenclamide, glimepiride, or diet alone according to crossover design. Scans were obtained before and after 4.5 min of forearm ischemia. Postischemic vasodilation and hyperemia were expressed as percent variations in vessel diameter and blood flow. RESULTS: Postischemic vasodilation and hyperemia were, respectively, 5.42 +/- 0.90 and 331 +/- 38% during glibenclamide, 5.46 +/- 0.69 and 326 +/- 28% during glimepiride, and 5.17 +/- 0.64 and 357 +/- 35% during diet treatment (NS). These results were similar to those found in the nondiabetic patients (6.44 +/- 0.68 and 406 +/- 42%, NS). CONCLUSIONS: In type 2 diabetic patients, the vasodilating response to forearm ischemia was the same whether patients were treated with diet treatment alone or with glibenclamide or glimepiride at blood glucose-lowering equipotent closes.

Cerebral blood flow reserve in patients with syndrome X.

BACKGROUND: Patients with syndrome X frequently show disorders of oesophageal motility, bronchial reactivity or impaired vasodilator capacity of peripheral vascular beds. For these reasons, it has been suggested that syndrome X may represent a generalized abnormality of vascular and non-vascular smooth muscle function, rather than an isolated coronary problem. OBJECTIVE: To measure the cerebral blood flow and cerebrovascular vasodilator reserve in syndrome X patients and in controls. METHODS: We measured the cerebral blood flow and cerebrovascular reserve in 16 patients with syndrome X [11 women, aged 59.5 +/- 10.8 years (mean +/- SD)] and in 16 age-matched healthy volunteers. No patients had evidence of stenoses of carotid and vertebral arteries on Doppler sonography. Cerebral blood flow was measured by the 133Xe inhalation method, using the initial slope index as the cerebral blood flow index. After a baseline measurement, a second cerebral blood flow measurement was performed 20 min after administration of 10 mg/kg acetazolamide intravenously. Acetazolamide is known to be a potent cerebral vasodilator. The percentage increase in cerebral blood flow after acetazolamide administration was considered an index of cerebrovascular vasodilator reserve. RESULTS: Under basal conditions, both regional and global cerebral blood flow were nearly identical in the control group and in the patient group (initial slope index 50.2 +/- 3.8 versus 50.3 +/-6.2, NS). After acetazolamide administration, the cerebral blood flow increase was 29.0 +/- 14% in the patient group and 29.5 +/- 11% in the control group (NS). CONCLUSIONS: Our data show that cerebral blood flow and cerebrovascular vasodilator reserve were preserved in a series of patients with syndrome X. These results are not consistent with the hypothesis of a diffuse smooth muscle disorder.