Atropine in Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)

Not Applicable

Completed

Brief Summary: To test the hypothesis that increasing the sinus node rate with atropine treatment prior to exercise will reduce exercise-triggered ventricular ectopy compared to baseline in patients with CPVT.

Detailed Description: This is a prospective cross-over trial that will enroll eligible patients with CPVT and perform a baseline treadmill exercise tolerance test (ETT) followed by a repeat treadmill ETT with I.V. atropine administered immediately prior to exercise. Atropine is a parasympathetic blocker and results in sinus tachycardia, which is expected to reduce the diastolic interval thereby reducing delayed after depolarizations and ventricular ectopy compared to baseline. Both ETTs will be performed on the same day with two hours of rest scheduled between ETTs. The primary analysis will be a paired comparison of the number of ventricular ectopic beats recorded during exercise (and recovery) at baseline and following pre-treatment with atropine. Secondary endpoints will include the presence of ventricular ectopy (yes/no), complex ventricular ectopy (couplets or greater, yes/no), and the number of runs of complex ventricular ectopy.

Recruitment & Eligibility

Inclusion Criteria

Age >/= 6 years
Able to provide written informed consent
Clinical diagnosis of CPVT
Able to exercise on a treadmill
Successful completion of a minimum of 2 exercise stress tests without adverse events

Exclusion Criteria

Contraindication to treadmill stress testing according to Vanderbilt University Medical Center's clinical protocols (unstable angina, decompensated congestive heart failure, severe hypertension (≥ 170/90 mmHg), acute myocardial infarction (<4 days), moderate to severe aortic stenosis, acute pulmonary embolism, severe pulmonary hypertension, outflow tract obstruction, hypertrophic cardiomyopathy, left main coronary stenosis, left bundle branch block)
Females who are pregnant
In the judgement of the investigator, any clinically significant ongoing medical or surgical condition that might jeopardize the subject's safety or interfere with the conduct of the study

Arm && Interventions

Group	Intervention	Description
Treadmill then Treadmill with Atropine	Exercise treadmill test	Patients will undergo treadmill exercise at baseline, then Patients will undergo treadmill exercise after IV atropine
Treadmill then Treadmill with Atropine	Atropine	Patients will undergo treadmill exercise at baseline, then Patients will undergo treadmill exercise after IV atropine

Primary Outcome Measures