Rhythm outcomes after aortic valve surgery: Treatment and evolution of new‐onset atrial fibrillation

Abstract Background The impact of new‐onset atrial fibrillation (AF) after aortic valve (AV) surgery on mid‐ and long‐term outcomes is under debate. Here, we sought to follow up heart rhythms after AV surgery, and to evaluate the mid‐term prognosis and effectiveness of treatment for patients with new‐onset AF. Methods This single‐center cohort study included 978 consecutive patients (median age, 59 years; male, 68.5%) who underwent surgical AV procedures between 2017 and 2018. All patients with postoperative new‐onset AF were treated with Class III antiarrhythmic drugs with or without electrical cardioversion (rhythm control). Status of survival, stroke, and rhythm outcomes were collected and compared between patients with and without new‐onset AF. Results New‐onset AF was detected in 256 (26.2%) patients. For them, postoperative survival was comparable with those without new‐onset AF (1‐year: 96.1% vs. 99.3%; adjusted P = .30), but rate of stroke was significantly higher (1‐year: 4.0% vs. 2.2%; adjusted P = .020). With rhythm control management, the 3‐month and 1‐year rates of paroxysmal or persistent AF between patients with and without new‐onset AF were 5.1% versus 1.3% and 7.5% versus 2.1%, respectively (both P < .001). Multivariate models showed that advanced age, impaired ejection fraction, new‐onset AF and discontinuation of beta‐blockers were predictors of AF at 1 year. Conclusions In most cases, new‐onset AF after AV surgery could be effectively converted and suppressed by rhythm control therapy. Nevertheless, new‐onset AF predisposed patients to higher risks of stroke and AF within 1 year, for whom prophylactic procedures and continuous beta‐blockers could be beneficial.

been well reported that new-onset AF after aortic valve (AV) procedures elevates in-hospital mortality, while its sole effect on long-term endpoints remain controversial. [3][4][5] It should be noted that most of the studies attempted to relate new-onset AF to late events directly, without detailed heart rhythm follow-ups to support the causal relationship.
Regarding the optimal management of postoperative new-onset AF, current guidelines and recent trials recommend both rate control and rhythm control therapies. 1,6 At our institution, rhythm control is the preferred choice, and conversion is promptly performed for newonset AF. However, there is a lack of clinical and rhythm data to validate the mid-term effectiveness of such strategy. Furthermore, in addition to the well-known predictors of postoperative new-onset AF (e.g., age and left atrial size), risk factors that may predispose patients to long-term AF after AV surgery are also clinically relevant.
Hence, in this study, we aimed to (1) follow up heart rhythm after AV surgery; (2) compare clinical and rhythm outcomes between those with rhythm controlled new-onset AF and those who remained in sinus rhythm throughout postoperative hospitalization; and (3) identify predictors of paroxysmal or persistent AF at 1 year. We excluded patients with histories of AF, atrial flutter or atrial tachycardia, hyperthyroidism, and those who underwent cardiac reoperations. Concomitant procedures were limited to root reconstruction and ascending aortic repair. Patients undergoing transapical transcatheter AV implantation were also excluded.

| Study population
After screening, 978 patients were selected as the study cohort ( Figure 1). The heart rhythm of each patient was monitored continuously from postoperative day 0 until discharge using telemetry. New-onset AF was defined as postoperative AF that lasted at least for 30 s or recurred during hospitalization. 9 Whenever a period of AF was noted by the nursing staff, the physician on-call would be informed and respond accordingly. Data of the rhythm control treatment, including intravenous and/or oral use of Class III antiarrhythmic drugs with and without beta-blockers and electrical cardioversion, were collected by interrogating records of daily rounds and order lists.

| Operative procedures
Warfarin therapy was initiated on postoperative day 0 in all patients, and doses were titrated to achieve an international normalized ratio of 2.0-3.0. Patients with new-onset AF that was not successfully converted were discharged on continuous oral amiodarone or sotalol for 3 months. Antiarrhythmic drugs were discontinued in patients with completed 3-month regimen and in those who developed drug-related side effects, including dizziness, blurred vision, cough, dyspnea, symptomatic bradycardia, electrocardiogramconfirmed long-QT syndrome or ventricular tachycardia.
Heart rhythm follow-ups included electrocardiogram, 24-h Holter monitoring and pacemaker interrogation, which were performed at the discretion of the referring cardiologist and the operating surgeon.
Specifically, electrocardiogram and pacemaker interrogation were repeated at 1, 3, 6, and 12 months after surgery, and yearly thereafter. and anticoagulation therapies were used in patients with persistent AF who had undergone at least 1 electrical cardioversion or transcatheter ablation, and in those who refused those procedures.

| Follow-up
The primary outcomes of this study were all-cause mortality and stroke. The secondary outcomes were heart rhythm statuses at 3 months and at 1 year after surgery. Data of patient status and therapy after discharge were prospectively collected via telephone calls and the outpatient clinic database. Collection of follow-up data was .004 Red blood cell (IU) investigators (B.X. and S.Y.) who were blinded to the baseline and perioperative data.

| Rhythm follow-up and predictors of AF
Details of rhythm follow-ups and medications during follow-up were shown in Figure 1 and in Table 3 Table 4).

| DISCUSSION
The main findings of this study are twofold. First, by following up clinical and heart rhythm outcomes after AV surgery, we found that patients who developed new-onset AF during hospitalization were at higher risks of postoperative stroke and AF at 1 year, compared with those without new-onset AF. Second, rhythm control strategy was effective to restore sinus rhythm with a > 90% success rate at 1 year, which could be augmented by continuous use of beta-blockers after 3 months.

| Limitations
There are several limitations that should be recognized in the present study. First, this is a single-center cohort study that does not include prospective enrollment or randomization. Second, the study cohort might include patients with subclinical AF that was not detected by preoperative examinations. In addition, patients were not accessible to continuous rhythm monitoring, which might have led to underestimated rates of AF after discharge. 19

| CONCLUSIONS
New-onset AF is a common complication after AV surgery that can be effectively managed by rhythm control therapy with a > 90% successful conversion rate. However, despite those efforts, patients with new-onset AF are predisposed to higher risks of stroke and AF at 1 year. Continuous use of beta-blockers may be useful to reduce recurrence of AF.