Blood cells characteristics as determinants of acute myocardial infarction.

BACKGROUND: The aim of this study is to analyse the relation between red blood cells, platelets morphology and acute myocardial infarction (AMI), and to assess whether they could supplement the role of traditional cardiac biomarkers in the early identification of patients with AMI. METHODS: All consecutive patients admitted to our emergency department between the 1st January and the 31st August 2009 due to chest pain of suspected cardiac origin were included in the study. All the patients underwent physical examination, a 12-lead ECG, blood sampling for determination of cardiac troponin I and a complete blood count. RESULTS: A percentage of 6.7% of the 1971 patients had a confirmed diagnosis of AMI. Mean corpuscular volume (MCV), red blood cells distribution width (RDW) and platelets count (Plt) did not differ between patients with and without AMI. However, the mean platelet volume (MPV) was significantly higher in AMI patients (7.9 vs. 7.7 fL; p=0.0457). After stratification for gender, men with AMI displayed a lower RDW (p=0.0464) and a higher MPV (p=0.0062) as compared with those without AMI. The MCV and Plt were not significantly different. Women with AMI had a higher RDW (p=0.0079) as compared with those without AMI, while the MCV, Plt and MPV were not significantly different. CONCLUSIONS: Our study partially confirms previous data on the association between MPV or RDW and AMI. The inclusion of these parameters along with other conventional cardiac biomarkers might be a valuable perspective when evaluating patients with suspected AMI, although gender differences should be taken in account.

Survival benefits of different antiadrenergic interventions in pressure overload left ventricular hypertrophy/failure.

We observed previously that in rats with aortic banding (Bd), development of left ventricular (LV) hypertrophy is opposed by beta-blockade, whereas interventions interfering with alpha-adrenoceptor function also inhibit interstitial fibrosis. To assess whether these differential structural effects do translate into different effects on LV function and on heart failure mortality, Bd or sham Bd 8-week-old rats were randomized to vehicle treatment (Vh), chemical sympathectomy ([Sx] 6-hydroxydopamine, 150 mg/kg IP twice a week), beta-adrenoceptor blockade (propranolol [Pro], 40 mg/kg per day PO), or alpha-adrenoceptor blockade (doxazosin [Dox], 5 mg/kg per day PO). After monitoring survival for 10 weeks, the survivors were anesthetized to undergo echocardiography and intraarterial blood pressure measurement. Bd-Vh rats showed increased LV and lung weights, as well as LV dilation, depressed endocardial and midwall fractional shortening and a restrictive transmitral diastolic flow velocity pattern. Compared with Bd-Vh rats, all of the actively treated Bd rats showed less LV hypertrophy, LV dilation, and lung congestion but no less depression of midwall fractional shortening. In contrast, Sx and Dox but not Pro treatment were also associated with lesser degrees of diastolic dysfunction and, even more importantly, with a striking increase in survival (sham banded rats, 100%; Bd-Vh, 40%; Bd-Pro, 51%; Bd-Sx, 83%; and Bd-Dox, 82%). Although Pro, Sx, and Dox provide similar midterm protection from development of LV hypertrophy and dysfunction and from circulatory congestion, only Sx and Dox favorably affected mortality. These findings indicate that in the aortic banding rat model, alpha-adrenoceptors are importantly involved in the pathogenesis of cardiovascular deterioration and disease progression.

Sympathectomy or doxazosin, but not propranolol, blunt myocardial interstitial fibrosis in pressure-overload hypertrophy.

The adaptive changes that develop in the pressure-overloaded left ventricular (LV) myocardium include cardiomyocyte hypertrophy and interstitial fibrosis. Although the former is known to depend to a sizeable extent on sympathetic (over)activity, little information exists whether the same applies to the latter, ie, whether excess catecholamine exposure contributes to the imbalance between collagen deposition by fibroblasts and degradation by matrix metalloproteases (MMPs), eventually leading to LV collagen accumulation. Sprague-Dawley rats were subjected to abdominal aortic banding (B) or sham operation (S) and treated with beta-blockade (Bb, oral propranolol, 40 mg/kg per day), chemical sympathectomy (Sx, 6-hydroxydopamine, 150 mg/kg intraperitoneal twice per week) or vehicle (Vh). Ten weeks later, systolic blood pressure, LV weight, collagen abundance (computer-aided histology), zymographic matrix metalloproteinase (MMP)-2 activity and its specific tissue inhibitor concentration (TIMP-2) were measured. Both sympathectomy and beta-blockade failed to attenuate the banding-induced blood pressure elevation but significantly attenuated the attendant LV hypertrophy. As expected, pressure-overload hypertrophy was associated with interstitial fibrosis (collagen: 4.37+/-1.23% BVh versus 1.23+/-0.44% SVh, P<0.05), which was abolished by sympathectomy (2.55+/-1.31%, P=not significant versus SSx) but left unchanged by beta-blockade (4.11+/-1.23%, P<0.05 versus both SBb and BSx). beta-blockade, but not sympathectomy, was also associated with an increased TIMP-2/MMP-2 ratio (P<0.05), indicating reduced interstitial collagenolytic activity. In separate groups of banded and sham-operated rats, treatment with the alpha-receptor blocker doxazosin (10 mg/kg per day) displayed similar antifibrotic and biochemical effects as sympathectomy. Thus in the course of experimental pressure overload, the sympathetic nervous system plays a major pro-fibrotic role, which is mediated via alpha-adrenergic but not beta-adrenergic receptors.