Supraventricular ectopic activity predicts postoperative atrial fibrillation, new onset atrial fibrillation and worse survival in obstructive hypertrophic cardiomyopathy.

Background: Supraventricular ectopic activity (SVEA) is a marker of foci that may initiate atrial fibrillation (AF) and is associated with worse survival. The types and frequencies of SVEA for predicting postoperative AF (POAF), new-onset AF, and clinical outcomes in obstructive hypertrophic cardiomyopathy(oHCM) remain unknown.

Method: Our study consecutively recruited 961 patients with oHCM. All patients underwent a 24-hour Holter monitor before surgery.

Results: POAF incidence was 20.7% and increased with the burden of premature atrial contractions (PACs). Multivariable analysis showed that supraventricular tachycardia (SVT) was independently associated with POAF, with the model including SVT yielding the largest area under the curve (AUC) [0.710, 95%CI 0.670-0.750] for predicting POAF. During a median follow-up of 2.9 years, 12 deaths, 60 new-onset AF, and 139 composite endpoints were observed. A Spearman correlation indicated a linear relationship between the incidence of new-onset AF and composite endpoints with PAC frequency. The Kaplan-Meier survival curves demonstrated that patients with PACs >200 beats/day had significantly higher cumulative rates of new-onset AF[HR 3.13, (95%CI 1.74-5.62), p<0.001] and composite endpoints [HR 2.00, (95%CI 1.30-3.06), p=0.002] than their counterparts. Adding PACs >200 beats/day to the multivariable model significantly improved net reclassification improvement (NRI) and integrated discrimination improvement (IDI) for predicting new-onset AF (NRI=0.264, IDI=0.033) and composite endpoints (NRI=0.233, IDI=0.014).

Conclusion: The incidence of POAF was 20.7%, increasing with PACs severity. Furthermore, PACs burden was positively associated with a higher incidence of adverse events. Specially, PACs>200 beats/day may best predict a higher incidence of new-onset AF and worse survival.