[Appraisal of the state of the autonomic nervous system in hypertrophic cardiomyopathy by the analysis of heart rate variability]. / Aproximación al conocimiento del estado del sistema nervioso autónomo en la miocardiopatía hipertrófica mediante el análisis de la variabilidad de la frecuencia cardíaca.

INTRODUCTION: The analysis of heart rate variability has been accepted as a non-invasive method to evaluate the influence of the autonomic nervous system over the heart. Although heart rate variability has been used during the last decade in several illnesses the studies in hypertrophic cardiomyopathy are scarce. OBJECTIVES: We report the activity of the autonomic nervous system in patients with hypertrophic cardiomyopathy using the analysis of heart rate variability. PATIENTS AND METHODS: Heart rate variability was evaluate by the analyzing 24-h ambulatory electrocardiograms (Holter) in 20 patients with hypertrophic cardiomyopathy and in 15 controls. This method has been used to measure heart rate variability. Spectral analysis of the frequencies were calculated using fast Fourier transformation. Spectral heart rate variability was computed as high (0.15 to 0.40 Hz) low (0.04 to 0.15 Hz) and total (0.01 to 1.0 Hz). We compared the relation between low/high frequency as an index of the sympathetic/parasympathetic balance. All data are expressed as mean value +/- SD. The unpaired Student t-test was used. A two tailed p valued < 0.05 was considered statistically significant. RESULTS: There were no differences in the mean heart rates among the patients with hypertrophic cardiomyopathy and normal subjects (mean +/- SD: 71 +/- 9 versus 74 +/- 11 beats/minute; p = NS) while there was a significant decline in total spectral (mean +/- SD: 7.14 +/- 1.1 versus 7.57 +/- 0.6 ln [ms2]; p = 0.02) and high (mean +/- SD: 5.22 +/- 0.8 versus 5.63 +/- 1.3 ln [ms2]; p = 0.04) as well as in low spectral frequency of heart rate variability (mean +/- SD: 22 +/- 0.8 versus 5.63 +/- 1.3 ln [ms2]; p = 0.04) in patients with hypertrophic cardiomyopathy. There were no differences in the low/high frequency component ratio in these patients (mean +/- SD: 1.1 +/- 0.1 versus 1.2 +/- 0.1 ln [ms2]; p = NS). CONCLUSIONS: These facts suggest that the patients with hypertrophic cardiomyopathy have an alteration in the autonomic nervous system: sympathetic (low spectral frequencies) and parasympathetic activity (high spectral frequencies), although this does not reflect an imbalance between sympathetic and parasympathetic activities (relation of low to high spectral frequencies).

[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.

[Cardiomyopathy (X). Clinical approach to the patient with hypertrophic cardiomyopathy]. / Miocardiopatías (X). Actitud clínica ante el paciente con miocardiopatía hipertrófica.

Hypertrophic cardiomyopathy is a clinical and anatomofunctional entity that determines a series of hemodynamic consequences closely related to sintomatology. Left ventricular hypertrophic, subaortic stenosis, diastolic dysfunction and myocardial ischemia are the different pathophysiology mechanisms that generate similar clinical manifestations. Sintomatology defines two groups of patients with different profiles and clinical management. Ventricular arrhythmias are not uncommon and the forms that imply a darkest prognosis are supported symptomatic ventricular tachycardia and the induced ventricular tachycardia in patients that have suffered a cardiac arrest or have had syncopes. Basic explorations in all patients, in addition to physical examination, chest radiography and rest electrocardiogram, are Doppler echocardiography and Holter. Other explorations, such as Tallium-201 stress test, tilt test, electrophysiological and hemodynamic studies, are rationalized according to risk profile, sintomatology and responses to indicated treatment. In general, prognosis in asymptomatic patients is good and complex explorations are not justified nor are preventive character treatments. Symptomatic patients who have a higher risk must be studied more closely, and frequently require complex and invasive explorations. They also need pharmacological treatment and often more invasive therapeutical options, DDD pacemakers or surgery, if those fail.

[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.