Atrial Fibrillation in Advanced Heart Failure Patients Receiving Left Ventricular Assist Devices

Atrial Fibrillation in Cardiac Surgery Atrial fibrillation (AF) is a menacing problem in patients undergoing cardiac surgery, especially in older patients. Postoperative AF (POAF) is associated with increased mortality, hospital readmission, and hospital costs.1 Atrial fibrillation is present in up to 25% of patients with advanced heart failure, regardless of ischemic or nonischemic etiology.2 Despite the frequency with which it is encountered, there is little evidence about the effect of AF on both patient outcomes and if/how it should be treated in patients with advanced heart failure who are receiving left ventricular assist device (LVAD) therapies. In this issue of ASAIO Journal, there are three well-written original articles asking various clinical questions about the effects of AF on LVAD patients.3–5 Atrial Fibrillation in LVAD Patients Kurihara et al.3 asked the broad clinical question about the effect preoperative AF has on clinical outcomes in patients receiving continuous-flow LVADs. They observed an association between AF and pump thrombosis but no effect on survival and concluded that performing a concomitant rhythm operation at the time of LVAD placement is unnecessary. Deshmukh et al.4 asked the clinical question of the effect of new-onset POAF has following LVAD placement. They observed that 30% of LVAD patients developed new-onset POAF, but it was not associated with increased mortality or early thrombotic complications. Postoperative AF did, however, predict persistent AF and late thrombotic complications (ischemic strokes and pump thrombosis). They did not, however, recommend any prophylactic rhythm procedures but focused on aggressive medical treatment, including antiarrhythmic agents and anticoagulation. Finally, Anwer et al.5 asked a narrower question about whether the presence of preoperative AF should guide a concomitant and prophylactic restorative procedure on the tricuspid valve at the time of LVAD implantation. They observed more severe tricuspid regurgitation among AF patients but without a decrease in survival. They concluded that a concomitant tricuspid valve procedure (and rhythm restorative procedure) may be reasonable at the time of LVAD implantation. Putting It All Together Survival None of these studies observed a difference in survival for patients with AF. The study by Anwer et al.5 came the closest, but their survival curves diverged immediately after LVAD implantation and remained relatively stable up to 5 year follow-up. This suggests that in their cohort, AF was more of a marker of perioperative risk than a chronic problem that would lead to increased mortality over time. Thrombotic Complications These three studies produced mixed results on this topic. The two studies that measured pump thrombosis observed increased rates in patients with AF.4,5 It is unclear whether patient-related or device-related differences contribute to these discordant results. Unanswered Questions Concomitant Procedures The article by Anwer et al. once again brought up the question of concomitant tricuspid valve procedure (TVP) at the time of LVAD implantation and suggest that concomitant AF ablation could be considered in some patients.5–7 Unfortunately, their suggestion of concomitant TVP is based on the cohort who did not have TVP so this study is not able to really comment on whether TVP can prevent poor outcomes. Perhaps the Mayo group could ask this question in future studies by comparing all patients (matched by the presence of preoperative AF) and compare outcomes based those who did and did not get TVP at LVAD implantation. Additionally, the impact of additional concomitant procedures (rhythm and atrial appendage ligation) in such sick patients is unknown. Whether the increased operative time and expense associated with the energy source/atrial appendage occlusion device improves patient outcomes, and value, remains to be studied. Device Type The majority of patients in these three studies received HeartMate II (Abbott Laboratories, Abbott, IL) and HeartWare (Medtronic, Inc. Minneapolis, MN) LVADs. Whether the rates of pump thrombosis are similar in patients with AF receiving newer devices, such as HeartMate III (Abbott Laboratories), is unknown. Symptoms Although there does not appear to be a survival advantage to avoiding AF post LVAD implantation, one wonders if patients’ symptoms would improve if they were in sinus rhythm. One might also ask the question if avoiding AF might prevent late right ventricular failure, as it appears to be associated with worsening tricuspid valve regurgitation, and poor exercise tolerance observed in some patients with LVAD despite adequate flows. Antiarrhythmics How aggressively arrhythmias should be treated, in patients with LVAD, is also poorly understood. Although it does not appear that treating atrial arrhythmias in patients with LVAD will improve survival, it may result in fewer thrombotic complications. Anticoagulation Regimen Alternatives strategies for anticoagulation in patients with LVAD have been studied, but not exhaustively. The Minimal Anticoagulation Evaluation to Augment Hemocompatibility (MAGENTUM-I) study evaluated lower INR targets for patients with gastrointestinal (GI) bleeding with good clinical outcomes.8 Additional studies of increasing internal normalized ratio (INR) may need to be performed for patients with both LVAD and AF. Recovery One final unaddressed question is the effect of AF on the ability to recover hearts using LVAD and medical therapies. In our experience studying myocardial unloading to promote cardiac recovery, atrial fibrillation is negatively correlated with recovery.9,10 Perhaps when treating patients with higher likelihood of recovery, rhythm correction should be aggressively pursued. Conclusions The timing of these three articles demonstrates the urgent clinical need to better understand the effect of AF in patients who are eligible for advanced heart failure therapies. Many questions remain unanswered, however, with respect to the role of concomitant procedures at the time of LVAD implantation. Procedures to either protect against the effects of AF (TVP) or restore sinus rhythm may allow improved outcomes on LVAD support or even promote myocardial recovery and LVAD removal.