Risk of arrhythmic and nonarrhythmic death in patients with heart failure and chronic kidney disease

BACKGROUND

optimal utilization of therapies effective at preventing arrhythmic death but not nonarrhythmic death, for example, the implantable cardioverter-defibrillator (ICD), is challenging in patients with concomitant heart failure (HF) and chronic kidney disease (CKD), given the association of both conditions with competing risks of death.

OBJECTIVES

we examined the risk of arrhythmic and nonarrhythmic mortality in patients with different severities of HF and CKD.

METHODS

using individual patient data from the SOLVD, we categorized HF by New York Heart Association class and CKD severity by estimated glomerular filtration rate. Cox models with HF and CKD stages as time-dependent covariates were used to calculate hazard ratios for arrhythmic and nonarrhythmic death adjusted for age, gender, and enalapril allocation.

RESULTS

among 6,378 patients without an ICD (age 60 ± 10, left ventricular ejection fraction 27 ± 6, male 86%), there were 421 arrhythmic and 1188 nonarrhythmic deaths over a median follow-up of 34 months. Worse HF or CKD stages were associated with increased risk of both arrhythmic and nonarrhythmic death. The increase in the risk of nonarrhythmic death in the worst HF stage was disproportionately higher than that of arrhythmic death, and this disproportionate effect was more exaggerated in the presence of more advanced CKD.

CONCLUSION

while advanced CKD and HF stages are associated with increased risk of arrhythmic and nonarrhythmic death, benefits of ICDs in patients with more advanced disease may be limited by the preponderance of nonarrhythmic death.

Differential effects of statins (pravastatin or simvastatin) on ventricular ectopic complexes: Galpha(i2), a possible molecular marker for ventricular irritability

Retrospective studies suggest that statins might exert an antiarrhythmic effect on the heart. The mechanism of this effect is unclear. Parasympathetic stimulation of the heart has been shown to protect against ventricular arrhythmias. The goal of this study was to determine the effect of statins on ventricular arrhythmias and its correlation with changes in parasympathetic responsiveness and Galpha(i2) expression. Patients were randomized to pravastatin and simvastatin in a double-blind crossover design. Ventricular arrhythmias were determined by analysis of 24-hour Holter recordings. Spectral RR interval analysis of Holter studies determined peak high-frequency power fraction, which reflects parasympathetic modulation of heart rate. Expression of Galpha(i2), a molecular component of the parasympathetic response pathway, was determined by Western blots of patients' lymphocytes. Pravastatin treatment decreased the incidence of ventricular premature complexes by 22.5 + or - 3.4% (n = 20, p <0.05), couplets, and runs of 3 to 6 beats of nonsustained ventricular tachycardia from 9.8 + or - 2.67 to 3.9 + or - 1.25 events/patient/24 hours (n = 12, p <0.05). Pravastatin increased peak high-frequency fraction by 29.8 + or - 4.3% (n = 33, p <0.001), while Galpha(i2) expression increased by 51.3 + or - 22.5% (n = 21, p <0.05). Effects of simvastatin on ventricular premature complexes and nonsustained ventricular tachycardia were not significant. Relative changes in couplets and nonsustained ventricular tachycardia in pravastatin-treated patients correlated negatively with changes in Galpha(i2) and high-frequency fraction (rho = -0.588 and rho = -0.763, respectively, n = 12, p <0.05). In conclusion, these data suggest that pravastatin might decrease cardiac irritability via an increase in parasympathetic responsiveness and that changes in Galpha(i2) expression might serve as a molecular marker for this effect, which might play a role in the molecular mechanism of the antiarrhythmic effect of statins.