Abstract 9922: Increased Susceptibility to Arrhythmias, Hypertension, and Hypertrophy in a Rat Model of Exposure to Electronic, Heat-Not-Burn, or Conventional Cigarettes, or Marijuana

Abstract

Pathogenicity of cardiovascular disease (CVD) from smoking tobacco is well-known, but the CVD effects of vaping non-combustible tobacco products like e-cigarettes and heat-not-burn products (e.g., IQOS), and smoking marijuana (MJ), are less studied. We asked if 8 weeks of chronic use of e-cigs, IQOS, or MJ in rats would cause less adverse cardiac effects than tobacco cigarettes. We exposed SD rats to 1 session/day (10 puffs over 5 min) for 8 weeks with Marlboro Red cigarettes (Cig), JUUL, IQOS, 10% THC MJ (MJ), cannabinoid-depleted “placebo” MJ (pb-MJ), or air. We performed echocardiography and measured conscious systolic blood pressure (SBP) every 2 weeks. We then performed 24-hour conscious ECG telemetry and ex vivo optical mapping (OM) of arrhythmias and analyzed interstitial fibrosis. By 1 hour after exposure, SBP was acutely increased by all tobacco products and pb-MJ, while only marijuana reduced SBP. SBP of all non-air groups rose progressively over 8 weeks, exceeding 130 mmHg after 2 weeks, and 140 mmHg after 4 weeks. SBP increased by MJ was higher than those by JUUL, IQOS, or pb-MJ. Cardiac performance declined and ventricular mass increased. All non-air conditions led to reduced overall heart rate variability, including the total power, low and high frequency from the power spectrum, and SDNN, RMSSD, and NN9 from time-domain method. Poincaré plot suggested a similar distribution pattern of RR interval. Interestingly, when compared with air, reduced physical activity was found in all experimental groups. OM revealed that more arrhythmias were induced by electrical stimulation: Cig, JUUL, IQOS, pb-MJ, MJ had atrial fibrillation of 50%, 85.71%, 50%, 50%, 37.5% and left ventricular (LV) tachycardia of 62.5%, 71.43%, 37.5%, 37.5%, 75% respectively vs. 0% in air, P < .05. Sirius red fibrotic staining showed significantly more interstitial fibrosis of atria and LV in all groups compared to air. Although no significant difference in interstitial fibrosis was found among tobacco products, MJ promoted more LV fibrosis than pb-MJ. Therefore, the use of different non-cigarette tobacco products and marijuana can increase CVD risks by causing hypertension, reduced cardiac performance, increased LV hypertrophy, and susceptibility to arrhythmias.