Congenital long QT syndrome presenting as unexplained bradycardia.

Congenital long QT syndrome (LQTS) is a genetically autosomal heterogeneous disorder of the ion channels and causes about 10% of sudden death infant syndrome in newborns. Its estimated prevalence is approximately 1 in 2500, probably underestimated because of its clinical heterogenicity. Few cases of neonatal LQTS have been reported. In 4% of them, life-threatening arrhythmic events can be the first manifestation of LQTS. The authors report two cases of neonatal LQTS with heterogeneous genetic mutations. Both manifested by bradycardia, one since fetal life. One case had serious arrhythmias during beta blocker therapeutic establishment needing a pacemaker implantation. Genetic mutations found were not the most frequently described in association with neonatal bradycardia, thus the importance of this report. Presentation with bradycardia is relatively frequent in neonatal period, thus LQTS should be actively investigated in neonates with unexplained bradycardia. Beta blocker therapy reduces QTc and avoids arrhythmic events and sudden death.

Prevalence and predictors of coronary artery disease in patients with a calcium score of zero.

The absence of coronary calcification is associated with an excellent prognosis. However, a calcium score of zero does not exclude the presence of coronary artery disease (CAD) or the possibility of future cardiovascular events. Our aim was to study the prevalence and predictors of coronary artery disease in patients with a calcium score of zero. Prospective registry consisted of 3,012 consecutive patients that underwent cardiac CT (dual source CT). Stable patients referred for evaluation of possible CAD that had a calcium score of zero (n = 864) were selected for this analysis. The variables that were statistically significant were included in a multivariable logistic regression model. From 864 patients with a calcium score of zero, 107 (12.4%) had coronary plaques on the contrast CT (10.8%, n = 93 with nonobstructive CAD and 1.6%, n = 14 with obstructive CAD). By logistic regression analysis, the independent predictors of CAD in this population were age >55 years [odds ratio (OR) 1.63 (1.05-2.52)], hypertension [OR 1.64 (1.05-2.56)] and dyslipidemia [OR 1.54 (1.00-2.36)]. In the presence of these 3 variables, the probability of having coronary plaques was 21%. The absence of coronary artery calcification does not exclude the presence of coronary artery disease, but the prevalence of obstructive disease is very low. In this population, the independent predictors of CAD in the setting of a calcium score of zero were hypertension, dyslipidemia, and age above 55 years. In the presence of these 3 predictors, the probability of having CAD was almost 2 times higher than in the general population.