[The effect of the mean platelet volume on the short-term prognosis of acute myocardial infarct]. / Influencia del volumen plaquetario medio sobre el pronóstico a corto plazo del infarto agudo de miocardio.

INTRODUCTION AND OBJECTIVES: The increase of mean platelet volume in the late phase of myocardial infarction is an independent predictor for recurrent myocardial infarction and death, but the association between this finding and the short-term prognosis after acute myocardial infarction is unknown. The goals of this study were to assess the influence of mean platelet volume on the risk of death, recurrent ischemic events or cardiac heart failure during the in-hospital phase of myocardial infarction and to analyse the relationship between mean platelet volume and several demographic and clinical variables registered on admission. MATERIAL AND METHODS: A population of 1,082 patients with acute myocardial infarction were distributed in two groups according to the platelet volume measured on admission: group 1, mean platelet volume > 9 fl (n = 443) and group 2, mean platelet volume < or = 9 fl (n = 639). The difference between both groups on the end-point of this study were assessed by univariate and multivariate statistical methods. An univariate analysis was also applied to assess the relationship between platelet volume and the baseline variables. RESULTS: A mean platelet volume > 9 fl was associated with a significant increase of risk for the combined end-point considered (OR = 1.37; p = 0.026). By univariate analysis, an increased platelet volume was related to a higher risk of cardiac failure (OR = 1.46; p = 0.01) and a non-significant increase in the incidence of recurrent ischemic events (OR = 1.35; p = 0.07). In addition, a large platelet volume was also associated with a higher prevalence of prior myocardial infarction, arterial hypertension and diabetes mellitus. CONCLUSIONS: The results of this study suggest that the increase of mean platelet volume on admission is an independent risk factor for cardiac heart failure and is associated with a non significant higher rates of ischemic events during the recovery phase of acute myocardial infarction.

[Clinical characteristics and hospital mortality of acute myocardial infarction in elderly patients treated with thrombolytic agents]. / Características clínicas y mortalidad hospitalaria del infarto agudo de miocardio en ancianos tratados con fármacos trombolíticos.

OBJECTIVES: This study describes the clinical features of elderly patients with acute myocardial infarction treated with thrombolytics and the effect of such therapy on in-hospital mortality rates in these patients. METHODS AND RESULTS: A group of 463 consecutive patients older than 70 years with an acute myocardial infarction was studied. This population was divided into two groups: 157 patients who received thrombolytic therapy (group A) and 306 patients who did not (group B). Patients in group A were younger (77 vs 79 years; p = 0.01) and had a lower prevalence of females (32.5% vs 44.1%; p = 0.01), prior myocardial infarction (14% vs 28%; p = 0.0008), hypertension (38% vs 48%; p = 0.03), diabetes (17% vs 26%; p = 0.02), class Killip 3 at entry (3.5% vs 14%; p = 0.001), a higher frequency of Q wave MI (88% vs 50%; p = 0.0001), inferior location of MI (51% vs 32%; p = 0.00007) and Killip 1 (70% vs 57%; p = 0.01) compared to group B. No significant differences on the inhospital mortality between either group were observed (25.5% vs 24.8%; p = 0.88). However, the thrombolysis was associated with higher mortality in patients with left ventricular dysfunction at entry (41% vs 84%; p = 0.0008) and in those patients with a delay of more than four hours from the onset of symptoms to admission (19% versus 30%; p < 0.1). CONCLUSIONS: 1) In the elderly with acute myocardial infarction, thrombolytic therapy is administered to a lower risk population; 2) our findings do not confirm the benefits of chemical thrombolysis on cardiac mortality in the elderly, and 3) in selected subgroups (Killip > 2 at entry, symptoms delay > 4 hours) the risk/benefit ratio of thrombolytic therapy should be reevaluated. However, care needs to be taken in evaluating the data because this study was not blinded and the number of patients included was relatively small.

[Study of heart rate variability in acute myocardial infarction and its relationship with ventricular function and other clinical variables]. / Estudio de la variabilidad de la frecuencia cardíaca en el infarto agudo de miocardio y su relación con la función ventricular y otras variables clínicas.

BACKGROUND: The influence of ventricular function (VF) on prognosis in acute myocardial infarction (AMI) is well known. Heart rate variability (HRV), as a neurohumoral parameter could predict VF after discharge in AMI patients. Our goal is to investigate the possible relation among HRV, VF and another clinical variables in AMI. PATIENTS AND METHODS: We studied 37 patients with AMI after hospital discharge. Age, AMI type, location, enzymes, treatment (thrombolysis versus no thrombolysis) were evaluated. The left ventricular ejection fraction (LVEF) was assessed by radionuclide ventriculography in 27 subjects. Twenty nine subjects without cardiopathy were the control group. Twenty four hour electrocardiographic recordings were obtained and a proper software was used to measure HRV. This was evaluated with time domain measures: RR interval, standard deviation of the mean RR interval (SDNN), standard deviation of the average of the RR intervals measured every 5 minutes during 24 hours (SDANN) and number of two consecutive RR intervals with a variability > 50 ms (pNN50). We considered a decreased variability if SDANN was less than 100 ms. Two groups were established: 1) low heart rate variability (LHRV) if SDANN was less than 100 ms, and 2) normal heart rate variability (NHRV) if SDANN was larger than 100 ms. Continuous variables were examined by the t-test, chi square for discrete ones and linear regression analysis was used to assess the relation among variables. A p < 0.05 was considered significant. RESULTS: The percentage of infarcted patients in the group of LHRV is 75%, whereas it is 14% in the control group (p < 0.05). SDANN, SDNN and pNN50 values are significantly lower (p < 0.05) in the AMI than in the control group. LHRV was more frequent in patients with complicated AMI with congestive heart failure. LVEF was significantly lower (35% vs 56%) in the LHRV than in the NHRV group. No significant differences were found among: site, type infarct, treatment or ventricular ectopy in the Holter before discharge. There is good correlation (r = 0.635; p < 0.05) between LVEF and HRV measures. No correlation was found between HRV and age, or the enzymatic size of infarction. CONCLUSIONS: 1) LHRV is frequent in the late phase of AMI, and 2) LHRV can be an indirect index of left ventricular failure.

[Changes in exercise capacity and in induced ischemia with an oral dose of 5 isosorbide mononitrate in patients with stable angina pectoris]. / Modificaciones en la capacidad de ejercicio y en la isquemia inducida con una dosis oral de 5-mononitrato de isosorbide en pacientes con angina de pecho estable.

In order to establish the effects of 5-isosorbide mononitrate on: the exercise capacity, the onset period of angina and ischemia along with the degree and on whether the duration time was prolonged up to 5 hours after the oral administration of 20 mg of this drug, we compare this drug against a placebo in a group of 15 patients with stable angina pectoris developed by effort who performed an exercise test using a bicycle ergometer. After the administration of 20 mg of 5-isosorbide mononitrate it was observed that onset time of angina (p less than 0.001), the onset time of ST decrease (p less than 0.002) and total time of exercise attained were significantly superior to those found in patients with placebo administration. Moreover, for the same degree of EKG ischemia (ST decrease) showed a superior exercise time was registered (p less than 0.002) after the administration of 5-isosorbide mononitrate (5-IM). Our results show that an oral dosage of 20 mg of 5-IM given to patients with stable angina pectoris increased the capacity and exercise tolerance delaying significantly the onset time of angina, the onset time of EKG ischemia and its decree induced by the effort up to 5 hours after its administration.