Hypertensive heart disease, ventricular dysrhythmias, and sudden death

Meta-analysis of left ventricular hypertrophy and sustained arrhythmias

Presence of left ventricular hypertrophy (LVH) has been reported to be associated with supraventricular and ventricular arrhythmias, but the association has not been systematically quantified and evaluated. A systematic search of studies in MEDLINE, EMBASE, CINAHL, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials databases was undertaken through April 2014. Studies reporting on LVH and sustained arrhythmias such as atrial fibrillation and supraventricular tachycardias (SVTs) and ventricular arrhythmias (tachycardia and fibrillation) were identified. Pooled effect estimates were calculated with random-effects models (DerSimonian and Laird). A total of 10 eligible studies with 27,141 patients were included in the analysis. The incidence of SVT in patients with LVH was 11.1% compared with 1.1% among patients without LVH (p<0.001). Patients with LVH had 3.4-fold greater odds of developing SVT (odds ratio 3.39, 95% confidence interval 1.57 to 7.31) than those without LVH, although significant heterogeneity was present (I2=98%). Meta-regression analyses revealed the heterogeneity to have originated from differences in the baseline covariates such as age, male gender, hypertension, and diabetes of the individual studies. The incidence of ventricular arrhythmias was 5.5% compared with 1.2% in patients without LVH (p<0.001). The occurrence of ventricular tachycardia or fibrillation was 2.8-fold greater, in the presence of LVH (odds ratio 2.83, 95% confidence interval 1.78 to 4.51), and there was no significant heterogeneity (I2=9%). Presence of LVH in hypertensive patients is associated with a greater risk of sustained supraventricular/atrial and ventricular arrhythmias, and there is an unmet need for identifying and refining risk stratification for this group.

Cardioprotective effects of the calcineurin inhibitor FK506 and the PAF receptor antagonist and free radical scavenger, EGb 761, in isolated ischemic/reperfused rat hearts

Effects of the calcineurin inhibitor FK506, the platelet-activating factor (PAF) antagonist, and free radical scavenger Ginkgo biloba extract, EGb 761, and their combination on reperfusion-induced ventricular fibrillation (VF), ventricular tachycardia (VT), and recovery of cardiac function were studied after 30 min of global ischemia followed by 2 h of reperfusion in isolated rat hearts. In the first series of studies, rats received a daily (oral) dose of 0, 1, 5, 10, 20, or 40 mg/kg/day FK506 for 10 days. FK506 dose-dependently reduced the incidence of reperfusion-induced total (irreversible plus reversible) VF from a value of 92% for untreated animals to 92% (NS), 83% (NS), 67% (NS), 33% (p<0.05), and 25% (p<0.05), for doses of 1-40 mg/kg/day, respectively, with effects on incidence of VT showing the same pattern. FK506, between 20 and 40 mg/kg/day, also resulted in significant recovery of postischemic cardiac function. In the second series of studies, rats were treated with EGb 761 alone or in combination with FK506. Whereas no significant reduction in arrhythmias or improvement in cardiac function resulted from a single intervention of EGb 761 at 25 mg/kg/day, combined treatment of rats with 25 mg/kg/day of EGb 761 and 1 or 5 mg/kg/day of FK506 resulted in a reduction in total and irreversible VF of 92% and 92% to 42% (p<0.05) and 33% (p<0.05), 25% (p<0.05) and 8% (p<0.05), respectively, versus untreated control animals, paralleled by similar effects on the incidence of VT and accompanied by significant improvements in postischemic cardiac function. Our results demonstrate a novel cardioprotective characteristic of FK506 and suggest that combination therapy by using FK506 plus EGb 761 synergistically improves postischemic cardiac function, while reducing the incidence of reperfusion-induced VF and VT, which may expand the clinical utility of FK506 and allow therapy with FK506 at lower doses than are currently useful.