A Clinical Score for Predicting Atrial Fibrillation in Patients with Cryptogenic Stroke or Transient Ischemic Attack

Abstract

Objectives: Detection of atrial fibrillation (AF) in post-cryptogenic stroke (CS) or transient ischemic attack (TIA) patients carries important therapeutic implications.

Methods: To risk stratify CS/TIA patients for later development of AF, we conducted a retrospective cohort study using data from 1995 to 2015 in the Stanford Translational Research Integrated Database Environment (STRIDE).

Results: Of the 9,589 adult patients (age ≥40 years) with CS/TIA included, 482 (5%) patients developed AF post CS/TIA. Of those patients, 28.4, 26.3, and 45.3% were diagnosed with AF 1-12 months, 1-3 years, and >3 years after the index CS/TIA, respectively. Age (≥75 years), obesity, congestive heart failure, hypertension, coronary artery disease, peripheral vascular disease, and valve disease are significant risk factors, with the following respective odds ratios (95% CI): 1.73 (1.39-2.16), 1.53 (1.05-2.18), 3.34 (2.61-4.28), 2.01 (1.53-2.68), 1.72 (1.35-2.19), 1.37 (1.02-1.84), and 2.05 (1.55-2.69). A risk-scoring system, i.e., the HAVOC score, was constructed using these 7 clinical variables that successfully stratify patients into 3 risk groups, with good model discrimination (area under the curve = 0.77).

Conclusions: Findings from this study support the strategy of looking longer and harder for AF in post-CS/TIA patients. The HAVOC score identifies different levels of AF risk and may be used to select patients for extended rhythm monitoring.

Keywords: Atrial fibrillation; Cardiovascular risk and prevention; Cryptogenic stroke; Rhythm monitoring.

Conflict of interest statement

Disclosures

The authors have no conflicts of interest to disclose.

© 2017 S. Karger AG, Basel.

Figures

Figure 1

Flow chart of cohort selection using both ICD-9 codes and processed clinical notes. AF was defined by having ICD-9 diagnosis of 427.31 and 427.32 at least 30 days after CS/TIA.

Figure 2

Distribution of when CS/TIA patients receiving diagnosis of AF by months. 28.4% of the patients received a new diagnosis of AF between 1–12 months post CS/ITA, 26.3% of patients at 1–3 years, and 45.3% at >3 years.

Figure 3

Three risk strata based on HAVOC score. In the derivation cohort, AF rate in the low, medium, and high risk strata was 2.5%, 11.8%, and 24.9% respectively. In the validation cohort, AF rate in the low, medium, and high risk strata was 2.6%, 11.1%, and 20.3% respectively. There is a significant increase in risk between each stratum (p<.0001) by Cochran-Armitage trending test for both derivation and validation cohorts.