DOI: 10.1161/circ.148.suppl_1.15635 ISSN: 0009-7322

Abstract 15635: Sex Differences in the Effect of Nocturnal Hypoxia on Right Ventricular Myocardial Blood Flow

Sohum Kapadia, Magdalena Malczewska, Attila Feher, Robert deKemp, RAN KLEIN, Henry K Yaggi, Edward J Miller, Albert J Sinusas, Stephanie Thorn, Ehimen Aneni
  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Introduction: Nocturnal hypoxia is common in patients with obstructive sleep apnea (OSA). However, it is unclear how nocturnal hypoxia affects the structure and function of the right ventricle (RV), and if there are sex differences in the impact of nocturnal hypoxia on RV dysfunction. We examined the sex-specific relationship between nocturnal hypoxia, as measured as T90% (time asleep with <90% oxygen saturation), and RV myocardial blood flow (MBF) and myocardial flow reserve (MFR).

Methods: RV MBF and MFR were examined for 78 patients who had a cardiac PET stress test and a sleep test between 2015 to 2019. MBF was analyzed using FlowQuant software (Ottawa, Canada). MFR was defined as the ratio of stress to rest MBF. We categorized reduced RV MFR as < 2.3 (corresponding to the median value) and nocturnal hypoxia as T90 ≥ 8%.

Results: The mean (± SD) age was 63 ± 10 years. Most patients (83%) were obese (BMI ≥ 30kg/m3). Fifty-one patients (63%) were female. Although not statistically significant, the median RV MFR was higher among females (2.4 vs. 2.2, p = 0.158). RV MFR was higher among those without nocturnal hypoxia compared to those with nocturnal hypoxia (2.4 vs. 2.0, p = 0.023). Among females, the median RV MFR was higher among those without significant nocturnal hypoxia (2.5 vs. 1.8, p = 0.004), while males showed no relationship (2.2 vs. 2.2, p = 0.696; see table for details). In age and BMI adjusted logistic regression analysis, patients with nocturnal hypoxia were 3X as likely to have reduced RV MFR (OR = 3.2, 95% CI: 1.1 - 9.3) and there was a significant statistical interaction by sex (p = 0.046).

Conclusions: These findings suggest that nocturnal hypoxia is associated with a reduction in RV MFR, more prominently among females. Future studies should focus on elucidating the pathophysiologic implications of our findings and understanding the biologic processes that account for the sex differences observed.

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