Implications of fetal premature atrial contractions: systematic review

Objective: Fetal heart-rate irregularities occur in 1–2% of pregnancies and are usually caused by premature atrial contractions (PAC). Although PAC are considered benign, they may be associated with cardiac defects and tachyarrhythmia. We aimed to determine the incidence of congenital heart defects (CHDs) and complications in fetuses with PAC. Methods: This was a systematic review and meta-analysis conducted in accordance with the PRISMA statement for reporting items for systematic reviews and meta-analyses. MEDLINE and EMBASE were searched from 1990 to June 2021 to identify studies on fetuses with PAC. The primary outcome was CHD; secondary outcomes were complications using the endpoints supraventricular tachyarrhythmia (SVT), cardiac failure and intrauterine fetal demise. Meta-analysis of proportions was performed, subdivided into high-risk and low-risk populations based on reason for referral. Pooled incidences with 95% CIs were calculated. Results: Of 2443 unique articles identified, 19 cohort studies including 2260 fetuses were included. The pooled incidence of CHD in fetuses with PAC was 2.8% (95% CI, 1.5–4.1%), when 0.6% is the incidence expected in the general population. The pooled incidence of CHD was 7.2% (95% CI, 3.5–10.9%) in the high-risk population and 0.9% (95% CI, 0.0–2.0%) in the low-risk population. SVT occurred in 1.4% (95% CI, 0.6–3.4%) of fetuses diagnosed with PAC. Cardiac failure was described in 16 fetuses (1.4% (95% CI, 0.5–3.5%)), of which eight were CHD-related. Intrauterine fetal demise occurred in four fetuses (0.9% (95% CI, 0.5–1.7%)) and was related to CHD in two cases. Conclusions: Our findings suggest that the risk of CHD in fetuses with PAC is 4–5 times higher than that in the general population. CHD was present more frequently in the high-risk population. Consequently, an advanced ultrasound examination to diagnose PAC correctly and exclude CHD is recommended. Complications of PAC are rare but can result in fetal demise, thus weekly fetal heart-rate monitoring remains advisable to enable early detection of SVT and to prevent cardiac failure.