Cardiomyopathy and the Use of Implanted Cardio-Defibrillators in Children

Children and adults with cardiomyopathy and ventricular dysrhythmias have a uniformly poor prognosis, despite medical therapy. The use of automatic implantable cardio-defibrillators in adult patients with medically resistant ventricular dysrhythmias has resulted in a positive impact on survival. Because of its size and former lack of programmability, the device has been used rarely in children. Four patients with cardiomyopathy, in whom refractory ventricular dysrhythmias were managed with automatic implantable cardio-defibrillators, are presented. Two of these children are the youngest and smallest known in whom the device has been used; one of them received the first programmable model. The use of the automatic implantable cardio-defibrillator may enhance survival in selected young patients.     

Acute coronary syndromes without chest pain, an underdiagnosed and undertreated high-risk group: insights from the Global Registry of Acute Coronary Events

STUDY OBJECTIVES: The clinical manifestations of acute coronary syndromes (ACSs) vary, and patients present frequently with symptoms other than chest pain. In this analysis, a large contemporary database has been accessed to define the frequency, clinical characteristics, and outcomes of patients presenting without chest pain across different diagnostic categories of ACS. DESIGN AND SETTING: The Global Registry of Acute Coronary Events is a multinational, prospective, observational study involving 14 countries. PATIENTS: Patients presenting to the hospital with a suspected ACS were stratified according to whether their predominant presenting symptoms included chest pain (ie, typical) or did not (ie, atypical). Demographics, medical history, hospital management, and outcomes were compared. MEASUREMENTS AND RESULTS: Of the 20,881 patients in this analysis, 1,763 (8.4%) presented without chest pain, 23.8% of whom were not initially recognized as having an ACS. They were less likely to receive effective cardiac medications, and experienced greater hospital morbidity and mortality (13% vs 4.3%, respectively; p < 0.0001) than did patients with typical symptoms. After adjusting for potentially confounding variables, increased hospital mortality rates were noted in patients with dominant presenting symptoms of presyncope/syncope (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.4 to 2.9), nausea or vomiting (OR, 1.6; 95% CI, 1.1 to 2.4), and dyspnea (OR, 1.4; 95% CI, 1.1 to 1.9), and in those with painless presentations of unstable angina (OR, 2.2; 95% CI, 1.4 to 3.5) and ST-segment elevation myocardial infarction (OR, 1.7; 95% CI, 1.2 to 2.2). CONCLUSION: Patients with ACSs who present without chest pain are frequently misdiagnosed and undertreated. With the exception of diaphoresis, each dominant presenting symptom independently identifies a population that is at increased risk of dying. These patients experience greater morbidity and a higher mortality across the spectrum of ACSs.     

Vasopressin antagonist analogs modified at position 7

Vasopressin antagonist analogs having alanine or glycine at position 7 were essentially equipotent with analogs with proline, N-methylalanine or sarcosine at position 7. This demonstrates that the conformational constraint imposed by an N-alkyl residue at position 7 is not necessary for binding of antagonist to the receptor, the exact opposite of what is seen in agonists. This suggests that antagonists bind to the receptor in a manner which is very different from that of agonists.     

Comparison of outcomes of patients with acute coronary syndromes with and without atrial fibrillation

Preexisting or new-onset atrial fibrillation (AF) commonly occurs in patients with an acute coronary syndrome (ACS). However, it is currently unknown if previous or new-onset AF confers different risks in these patients. To determine the prognostic significance of new-onset and previous AF in patients with ACS, we evaluated all patients with ACS enrolled in the multinational Global Registry of Acute Coronary Events (GRACE) between April 1999 and September 2001. We compared clinical characteristics, management, and hospital outcomes in patients with ACS and new-onset and previous AF with those without AF. Of a total of 21,785 patients with ACS enrolled in GRACE, 1,700 (7.9%) had previous AF and 1,221 (6.2%) had new-onset AF. Patients with any AF were older, more likely to be women, had more co-morbid conditions, and worse hemodynamic status. Most in-hospital adverse events (reinfarction, shock, pulmonary edema, bleeding, stroke, and mortality) were significantly higher in patients with any AF than those without AF. Only new-onset AF (not previous AF) was an independent predictor of all adverse in-hospital outcomes. We conclude that compared with patients with ACS without any AF, previous and new-onset AF are associated with increased hospital morbidity and mortality. However, only new-onset AF is an independent predictor of in-hospital adverse events in patients with ACS.     

Ambulatory Assessment of the QT Interval in Patients with Hypertrophic Cardiomyopathy: Risk Stratification and Effect of Low Dose Amiodarone

This study aims to assess the dynamics of the QT interval in patients with hypertrophic cardiomyopathy (HCM). Three consecutive QT intervals and the preceding RR intervals were measured on 24-hour ambulatory electrocardiograms at 30-minute intervals in ten high risk patients with HCM (sudden cardiac death [SCD] and/or documented ventricular fibrillation), aged 29 ± 17 years, compared with ten age and sex matched low risk patients with HCM (no syncope, no adverse family history, and no ventricular tachycardia on Holter monitoring), and ten normal subjects. Another ten patients who were on amiodarone therapy (200-mg daily) were also studied. Patients witb intraventricular conduction defects were excluded. There were 4,424 pairs of QT intervals and their preceding RR intervals were measured in this study. A nonsignificant prolongation in the QT interval and a significant prolongation in QT_c values (Bazett's and Fridericia's formulas) were demonstrated in patients with HCM compared with normals. There were no significant differences in the QT and QT_c between high and low risk patients. The slope of regression line for the QT against RR interval was significantly different between normals and HCM (0.1583 ± 0.040 vs 0.2017 ± 0.043. P < 0.05), but not between high and low risk patients. Amiodarone significantly prolonged the QT and QT_c without significantly altering the slope of the regression line (0.2017 ± 0.043 vs 0.2099 ± 0.037, NS). Our findings support the observations that there is a prolonged QT interval in patients with HCM and that there is no significant use dependent effect of amiodarone on ventricular repolarization. In conclusion, ambulatory assessment of the QT interval provides an alternative method for the assessment of ventricular repolarization and for the assessment of use dependent effects of anti arrhythmic drugs on ventricular repolarization during normal daily activities. However, this method does not help in the identification of patients at high risk of SCD in HCM.