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Background: The effect of physical activity (PA) on incidence of atrial fibrillation (AF) is unclear in African Americans (AA). This study aimed to determine if higher levels of PA are associated with decreased incidence of AF in the Jackson Heart Study (JHS). Methods: Participants of the JHS with PA assessment and without previous AF at baseline were included in the study. PA was categorized based on the American Heart Association physical activity levels. Incident AF was defined as having 12 lead electrocardiogram evidence at a subsequent follow up, or a documented diagnosis code at the time of hospital discharge from 2000 to 2016. Cox proportional hazards models were used to evaluate for the association between baseline PA and incidence of AF. Given significant correlation between PA and baseline cardiovascular disease (CVD), stratified analysis was performed based on CVD status. Results: Of the 4,477 participants followed for a median of 12.5 years, 398 developed AF (7.13 cases per 1,000 person-years). Ideal and intermediate PA were associated with a reduced risk of incident AF compared with poor PA (unadjusted HRs with 95% CIs 0.47 [0.34 - 0.64] and 0.72 [0.58 - 0.90], respectively) (Table). After adjustment for traditional cardiovascular risk factors, the associations attenuated and became no longer significant (0.73 [0.53 - 1.00] and 1.00 [0.80 - 1.25], respectively). In stratified analysis based on baseline CVD status, in participants without baseline CVD, ideal PA was significantly associated with a reduced risk of AF while intermediate PA was not (0.68 [0.47 - 0.98] and 1.00 [0.78-1.29], respectively). In participants with baseline CVD, ideal PA or intermediate PA was not associated with incident AF. Conclusion: Ideal PA was associated with a reduced risk of AF in participants without baseline CVD in this AA community cohort. Our findings show intertwined relationship among PA, CVD, and incident AF. Physical activity could be a possible therapeutic target to reduce AF incidence in the AA general population without CVD.

Introduction: The impact of sex mismatch on outcomes after orthotopic heart transplant (OHT) remains unclear. We aimed to evaluate the change in left ventricle (LV) size based on donor and recipient sex and examine its association with the outcomes. Methods: This was a single institution, retrospective study among OHT recipients between Jan 2015 and Sept 2020. Patients were excluded if they were<18 years old, received OHT for congenital heart disease, had follow-up<6 months or missing donor variables. We collected donor (D) and recipient (R) clinical and echocardiographic characteristics. First and last echo post OHT were collected at least 2 months apart. Donor data was extracted from UNOS database. Primary outcome was the variation in donor heart size based on sex at first and last echo after transplant and the difference in survival or HF hospitalization. Statistical analysis (T test) was performed using Stata 15.1. Results: Among 156 reviewed patients, N=68 were included. Female (F) recipients (R) median age was 51±16 y, 25% were African-American (AA) while male (M) recipients median age was 56±12y and 19% were AA. Pre-transplant, MR had a higher RV and LV predicted heart mass and higher CO, CI by Fick. Aside from a higher prevalence of hypertension in MR, there was no difference in baseline characteristics. OHT allocation was MD/MR (66%); FD/FR (18%); FD/MR (4%); MD/FR (12%). LVEDD was bigger in MR on the first echo and remained on last echo post-transplant. There was no difference in degree of variation of LV parameters (LVEDD, LVESD, LV thickness) in MD/MR vs FD/MR and FD/FR vs MD/FR. Compared to sex matched, sex mismatched cohort had a non-significant trend towards a bigger degree of variation in LV size at first (-9% ± 10% vs -2% ± 21%;p=0.14) and last echo (-8% ± 12% vs -4% ± 14%;p=0.1).There were 18% (66% acute cellular rejection) cases of rejection split in half between sex matched and mismatched cohort. At a follow-up duration up to 6 years, 25% (N=17/68) of patients did not survive. There was no difference in survival or HF hospitalization in MR vs FR, in sex matched vs sex-mismatched. Conclusions: This is one of the first studies to examine the change in LV size and its impact on outcomes post OHT. The potential impact of LV behavior in M vs F is worth exploring on larger cohorts.

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