Effect of Atenolol Versus Ivabradine on HRV in TRS Patients on Clozapine With Tachycardia: A Randomised Control Trial.

Clozapine is the only drug approved for Treatment Resistant Schizophrenia. However, it has been associated with many adverse drug reactions including agranulocytosis, myocarditis, sialorrhea, constipation, orthostasis, tachycardia. There are many factors that have impacted the use of clozapine in TRS patients including physician hesitation, patient denial, stopping of drug due to Adverse drug reactions. Although Tachycardia should not be the reason to stop clozapine, but data shows that it leads to discontinuation of drugs in significant patient population. If patient on clozapine develops tachycardia; first orthostasis, myocarditis and systemic infection should be ruled out. Tachycardia traditionally have been treated with B1 adrenergic blockers such as Atenolol. But the problem with beta blocker medications is that significant proportion develops hypotension. Recently developed Ivabradine slows heart rate via I(f) current, and is not associated with much cardiac adverse effects. Recent Clinical trials have been carried out to show its effects on Clozapine associated tachycardia which shows promising results. Some studies suggest using Ivabradine in patient population that have contraindication for beta blockers. Although both of these drugs are used widely in clinical practice, but as Ivabradine is relatively new drug there have been no head-to-head comparison with Atenolol. A recent meta-analysis tried to compare treatment efficacy in these patients, but found no studies that met their inclusion criteria. This current study attempts to make such comparison and guide further research.