Editor's Note: Commentary based on Enriquez AD, Calenda B, Miller MA, Anyanwu AC, Pinney SP. The role of implantable cardioverter-defibrillators in patients with continuous flow left ventricular assist devices. Circ Arrhythm Electrophysiol 2013;6:668-674.¹

Garan AR, Yuzefpolskaya M, Colombo PC, Morrow JP, Te-Frey R, Dano D, Takayama H, Naka Y, Garan H, Jorde UP, Uriel N. Ventricular arrhythmias and implantable cardioverter-defibrillator therapy in patients with continuous-flow left ventricular assist devices: Need for primary prevention? J Am Coll Cardiol 2013;61:2542-2550.²

Summary

Ventricular arrhythmias (VAs) are common after implantation of a left ventricular assist device (LVAD) in patients with advanced heart failure. Implantable defibrillators have been shown to improve survival in patients with pulsatile-flow devices,³ and current guidelines recommend ICD implantation after LVAD.⁴ However, there is very limited data on the impact of ICDs on morbidity or mortality in patients with current, continuous-flow devices. Two recent studies have reported single-center series describing mortality and morbidity of post-LVAD patients with and without ICDs. These two constitute the largest series to date.

Methods and Patients

Enriquez et al.¹ performed a retrospective chart review of 106 patients who received the HeartMate II continuous flow LVAD between 6/08 and 4/12. Sixty-two had an active ICD and 36 did not. Patients without an ICD were more likely to have a disease duration < 1 year. VAs were defined as VT >30 seconds or VF. Those surviving greater than 30 days post-LVAD were analyzed. The primary analysis was the impact of VAs and ICDs on survival.

Garan et al. performed a prospective study enrolling 94 patients with a continuous flow LVAD, of whom 62 had had LVAD implantation prior to the enrollment period. Seventy-two had an active ICD and 22 did not.2 Patients without an ICD were more likely to have disease duration < 3 months. VA was defined as receiving appropriate therapy from the ICD or >30 seconds without treatment. The primary endpoint was occurrence of VA >30 days post-implant, mortality was a secondary endpoint.

Results and Conclusions

In Enriquez's¹ series, 37 patients (35%) had post-LVAD VAs (beyond 30 days post-implant). Pre-LVAD VAs did not predict post-LVAD VAs. Presentation of VAs included: asymptomatic (28%), symptoms of palpitations, lightheadedness or dyspnea (20%), hypotension or decreased LVAD flow (17%) and syncope or altered mental status in three patients (2.8%). Post-LVAD VAs were not associated with increased mortality nor with increased hospitalizations for CHF. Thirty-four percent of those with an ICD received an appropriate shock, but the ICD did not confer a survival benefit. The investigators conclude that, "while some episodes of VA may be clinically significant, VAs were not associated with a worse prognosis, and concomitant ICDs may not reduce mortality."

In Garan's series, 22 patients (23%) had post-LVAD VAs (beyond 30 days post-implant).² Pre-LVAD VA was the only predictor of post-LVAD VA. Six patients are described who had sustained VAs not treated by the ICD, three whose ICD failed to terminate the VA, one of whom ultimately died of refractory VT, two with VT below the rate-cut-off presenting after > 2 weeks of VT, and one without an ICD presenting with dizziness after four hours and VF. All six had signs of right heart failure and worsened renal function. Seven deaths are described, the one due to refractory VAs, rest non-arrhythmic, and there were no deaths in those discharged without an active ICD and no statistical difference in mortality between those with and without an active ICD. The investigators conclude, "Patients with pre-operative VA are at risk of recurrent VA while on CF-LVAD support and should have active ICD therapy to minimize sustained VA. Patients without pre-operative VA are at low risk and may not need active ICD therapy."

Perspective

Whether to implant an ICD in patients receiving a continuous-flow LVAD who do not already have one remains an important management issue. These two studies, the largest series to date, provide important information, although the authors reach different conclusions. The most important findings of the two studies are similar. Both studies confirm the high prevalence of late (> 30 days post-implant) VAs in patients with continuous-flow LVADs, and both show potentially deleterious clinical effects of sustained VAs in a small subset of patients despite adequate mechanical circulatory support. In both, there was no mortality benefit conferred by the ICD, leading Enriquez to conclude that ICDs may not be necessary. Garan concludes that, because VAs are frequent and prolonged VAs may result in RV failure, which carries a poor prognosis, ICDs should be implanted in those at high risk of VAs, which in his series were those with prior VAs. Interestingly, five out of six with VA-related morbidity did already have ICDs, although it is possible that the type of deleterious consequences reported might have been more common if fewer patients had had ICDs. It is important to note that even in patients without LVADs, an ICD-treated ventricular arrhythmia is not a surrogate for a life saved. This is even truer in those with continuous-flow LVADs, and while VAs were common, there was no mortality in either study which could be attributed to lack of an ICD.

Unfortunately, there are intrinsic limitations to these observational series which do not allow a definitive answer to the question. Most importantly, the numbers of patients who do not have active ICDs are just too small to draw a definitive conclusion. While there was no arrhythmia-related mortality in those without an ICD in either series, the combined number without an ICD is just 58. Also, patients without an ICD at the time of LVAD implant represent a very different population than those with one already in place, rendering comparisons difficult. Not surprisingly, in both series, those with ICDs had much longer duration of prior CHF. Most patients with longer durations of CHF will have previously met standard criteria for primary prevention ICD; those receiving LVADs first may either have had a more fulminant presentation, or presented for appropriate medical care later in the disease process.

Whether to implant an ICD in all patients receiving LVADs without one remains an open question. An ICD is not benign in LVAD patients; there are issues of infection, of physical and electrical interference, of shocking asymptomatic patients and the quality of life impact of these shocks. These two single-center series underscore the importance of collecting multicenter, prospective data. While a randomized clinical trial would be ideal, a large-scale prospective series of patients with LVADs without ICDs would also shed light on the question.

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References

1. Enriquez AD, Calenda B, Miller MA, Anyanwu AC, Pinney SP. The role of implantable cardioverter-defibrillators in patients with continuous flow left ventricular assist devices. Circ Arrhythm Electrophysiol 2013;6:668-674.
2. Garan AR, Yuzefpolskaya M, Colombo PC, Morrow JP, Te-Frey R, Dano D, Takayama H, Naka Y, Garan H, Jorde UP, Uriel N. Ventricular arrhythmias and implantable cardioverter-defibrillator therapy in patients with continuous-flow left ventricular assist devices: Need for primary prevention? J Am Coll Cardiol 2013;61:2542-2550.
3. Cantillon DJ, Tarakji KG, Kumbhani DJ, Smedira NG, Starling RC, Wilkoff BL. Improved survival among ventricular assist device recipients with a concomitant implantable cardioverter-defibrillator. Heart Rhythm 2010;7:466-471
4. Feldman D, Pamboukian SV, Teuteberg JJ, et al. The 2013 international society for heart and lung transplantation guidelines for mechanical circulatory support: Executive summary. J Heart Lung Transplant 2013;32:157-187.

Keywords: Arrhythmias, Cardiac, Defibrillators, Implantable, Heart Conduction System, Heart Failure, Heart-Assist Devices, Pulsatile Flow

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