Abstract 15317: Risk of Future Adverse Events in Patients Receiving Class IC Antiarrhythmic Drugs Who Have Elevated Coronary Artery Calcium Scores But Low-risk Cardiac Stress Test
Background: Class IC antiarrhythmic drugs (AAD) are a standard treatment of cardiac arrhythmias but are associated with harm in patients with prior myocardial infarction (MI)). Consensus guidelines have advocated that these drugs not be used in patients with coronary artery disease (CAD). However, the risk of Class IC AAD in patients with stable CAD, as demonstrated by an elevated coronary artery calcium (CAC) , but a low-risk cardiac stress test (LRCST), remains unclear. We hypothesized that the risk of future adverse cardiovascular events would not differ according to CAC severity among patients with an LRCST on Class Ic AAD treatment. Methods: We identified 355 patients without CAD and an LRCST (<5% ischemia) on cardiac stress PET before initiation of Class IC AAD. CAC was assessed using quantitative scores when available or qualitative CAC assessment on low-dose attenuation correction CT. Patients were divided into no/low CAC (i.e., quantitative score <100 or qualitative assessment of none/mild) or mod/severe CAC (i.e., quantitative score ≥100 or qualitative assessment of moderate/severe) The composite primary endpoint for this analysis was ventricular tachycardia/fibrillation (VT/VF), cardiac arrest, and all-cause death at one-year follow-up. Results: The majority of patients had no/low CAC (n = 278 [78.3%]) compared to mod/severe CAC (n = 77 [21.7%]). Those with no/low CAC were younger (62 vs 70, p<0.0001) and were more likely to have a higher BMI (33.1 v 30.4, p=0.007) when compared to the mod/severe CAC group. Other cardiovascular risk factors were similar between groups. There was no difference in the one-year primary composite outcome of VT/VF, cardiac arrest, and death between no/low CAC compared to mod/severe CAC (3.6% vs 5.2%, p=0.51). Conclusion: In patients receiving Class IC AAD therapy with an LRCST, an elevated CAC did not increase the risk of future adverse events. These data suggest that using Class IC AAD may be safe in patients with stable CAD (no ischemia/elevated CAC). Future prospective trials are needed to evaluate the safety of Class IC AAD in patients with elevated CAC.