Abstract Body (Do not enter title and authors here): Background
Atrial fibrillation (AF) is a leading cause of cardiovascular morbidity and mortality, and early detection is important for stroke prevention. The Apple Heart Study (AHS) demonstrated that wearable devices capable of irregular pulse notifications (IPN) can aid in identifying AF. The rates of subsequent diagnoses of cardiovascular disease (CVD) remain unknown.

Hypothesis
We aimed to evaluate how smartwatch-detected IPNs are associated with key cardiovascular diagnoses. We hypothesized that, among AHS participants, receiving IPNs would be associated with increased odds of subsequently reporting major cardiovascular diagnoses compared to participants without IPNs.

Methods
Out of 419,297 enrolled AHS participants, 288,533 (69%) individuals who completed the end-of-study survey (EOS) were included in this analysis. The self-reported diagnoses consisted of heart failure (HF), stroke, transient ischemic attack (TIA), myocardial infarction (MI), and pulmonary embolism (PE), considered individually and as a composite (MACE). Logistic regression was used to estimate odds ratios (ORs) for each diagnosis among IPN versus non-IPN participants, adjusted for sex, age, and CHA2DS2-VASc components.

Results
The EOS survey was completed by 908 notified participants (42% among the IPN cohort) and 287,625 non-notified participants (69% among the non-IPN cohort). IPN recipients were older, more often male, and had a higher comorbidity burden and CVD risk factors than the total cohort (Table 1). The IPN cohort reported higher rates of HF, MI, stroke, TIA, and PE compared to those who did not receive an IPN (Table 2). The fully adjusted logistic regression analysis showed increased odds of each diagnosis among the IPN group (Figure 1).

Conclusions
Participants with an IPN had higher odds of subsequently reporting major adverse cardiovascular diagnoses. These associations may reflect pre-existing conditions, underlying CVD risk, and comorbidities among participants who received an IPN, which has a high positive predictive value (PPV) for detecting AF. Given the elevated odds and high PPV, IPNs may warrant clinical consideration of evaluation for CVD or comorbidities, and future studies should assess the diagnostic and management pathways following IPNs.