Spironolactone protects against ventricular arrhythmia in ICD implanted patients
Treatment with the nonselective aldosterone receptor agonist spironolactone can significantly reduce ventricular arrhythmic events in patients with implantable cardioverter defibrillator (ICD), according to a Thailand study presented at the 23rd ASEAN Federation of Cardiology Congress (AFCC 2018).
“Spironolactone’s beneficial effect on reducing the incidence of ventricular arrhythmia has been proposed earlier. However, there is still not enough firm evidence to prove this hypothesis,” the investigators said.
To address such gap, the investigators prospectively examined the incidence of ventricular arrhythmic events, as well as ICD-related therapies, in 110 patients with left ventricular dysfunction (ejection fraction [LVEF] <50 percent) and New York Heart Association functional class I-III. The patients were implanted with either ICD or cardiac resynchronization therapy (CRT) device.
In the cohort, 48 received spironolactone (mean age 62.25 years; 66.67 percent male) while the remaining 62 did not (mean age 68.87 years; 75.81 percent male). Most patients had existing comorbidities, including diabetes mellitus (34.55 percent), hypertension (60.90 percent) and atrial fibrillation (31.82 percent).
Over a mean follow-up of 6 months, spironolactone produced significant reductions in ventricular arrhythmic events. On Poisson regression analysis, the incidence rate ratios (IRRs) were 0.65 for total episodes (p<0.001), 0.66 for nonsustained ventricular tachycardia (p<0.001) and 0.36 for ventricular tachycardia (p=0.012). [AFCC 2018, abstract P016]
Risk factors for developing ventricular arrhythmic events were LVEF ≤35 percent, male sex, older age, diabetes mellitus and hypertension.
Meanwhile, the nonselective aldosterone receptor agonist was associated with only a numerical decrease in the incidence of ICD-related therapies. The IRRs were 0.55 for total therapies (p=0.156) and 0.44 for ventricular antitachycardia pacing (p=0.073). A slightly higher rate of ICD shock was found in the spironolactone vs no treatment group, although the difference was not significant (IRR, 2.47; p=0.511).
The present data may have important clinical implications given that “in ICD implanted patients, ventricular arrhythmia leading to device shock results in many deleterious effects such as mortality and heart failure hospitalizations,” the investigators said.
Potential mechanisms by which spironolactone reduces the number of episodes of ventricular arrhythmias involve the drug’s antiarrhythmic actions, which include inhibition of electrical and structural cardiac remodelling, prevention of neurohumoral activation, blood pressure control and electrolyte disturbances stabilization. [Indian Heart J 2012;64:123-127]