Left ventricular assist devices (LVADs) have become the standard of care for patients with end-stage heart failure as a bridge-to-transplant (BTT) therapy [1] and as a destination therapy (DT) [2]. Over the past decade, numbers of LVAD implants in North America have grown exponentially, with over 15,000 patients undergoing LVAD implantation with continuous-flow LVAD. Approval of DT and other studies have accelerated the shift of timing of LVAD implantation to more ambulatory patients with heart failure in several years [3]. However, in the seventh annual Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) report, about 15% of all patients with INTERMACS profile 1 underwent LVAD implantation, and this rate has not changed in the past several years [4]. Therefore, it is important to discuss about the treatment strategy for patients at the INTERMACS level 1. The major problems of patients at the INTERMACS level 1 include not only decompensated hemodynamic condition but also other organ dysfunction or uncertified neurological status. At the first encounter for patients with cardiogenic shock, candidacy for DT or BTT LVAD is often unclear. In addition, because of the severity of their illness, the time to make a decision is very limited. Therefore, an alternative approach instead of primary implantable LVAD insertion may be considered using short-term mechanical circulatory support (MCS) for patients at the INTERMACS level 1. This treatment strategy is considered as a bridge-to-decision therapy. The merit of this strategy is that stabilization of hemodynamics and improvement of organ function can be achieved before long-term durable LVAD implantation. We reported favorable outcomes with CentriMag (Thoratec Co., Pleasanton, CA) VAD usage in patients with cardiogenic shock [5]. Moreover, recent advances in technology enable us to implant percutaneous short-term VADs such as extracorporeal membrane oxygenation (ECMO) and Impella (Abiomed, Danvers, MA). Percutaneous MCS devices can be less invasively implanted and are especially applicable for salvage treatment in critically ill cases [6]. This staged procedure has potential benefits to restore hemodynamic instability and end-organ function and may improve outcomes following definitive surgeries [7]. On the other hand, there remain several concerns in the bridge-to-decision strategy. Patients require a second intervention in cases which require subsequent implantable LVAD insertion. The second surgery after surgical short-term VAD requires adhesive dissection and more transfusions. Moreover, bridge-to-bridge surgery imposes increasing risk of device infection on patients [8]. In addition, bridging strategy using multiple MCS devices could increase medical cost and impose prolonged hospital stay. Thus, one-stage durable LVAD implantation is possibly advantageous with regards to cost and adverse consequences associated by multiple interventions. No studies have been conducted comparing outcomes between two strategies in INTERMACS 1 patients. Nonetheless, utmost careful attention must be paid for appropriate patient selection.

INTERMACS profile 1, which is defined as “crash and burn” or critical cardiogenic shock, includes a wide range of patients. Their etiologies can include acute myocardial infarction (AMI), acute decompensated cardiac myopathy, postcardiotomy shock, and fulminant myocarditis. All these patients do not necessarily need durable LVAD. Patients with fulminant myocarditis often rapidly deteriorate and require MCS; however, prognosis of fulminant myocarditis is much better than other etiologies, and many patients with fulminant myocarditis achieve myocardial recovery within 1 month [9–12]. Then, it is reasonable to implant temporary MCS rather than one-stage durable LVAD. The advantage of one-stage durable LVAD insertion is also quite limited in the setting of postcardiotomy shock. Temporary MCS such as ECMO should be considered in this situation. In patients with acute decompensating heart failure, it seems feasible to implant durable LVAD if they are already listed on a heart transplant list or are obvious candidates for DT therapy. Acute myocardial infarction (AMI) requires more complicated strategies. Almost all patients with AMI would never be listed for heart transplantation, and they are often obscure for BTT/DT candidacy because of coexistent multiple comorbidities. Moreover, these patients always receive antiplatelet therapy before and after percutaneous coronary intervention or other causes. There have been very few reports on one-stage implantation for AMI [13, 14]. However, the number of implantable LVAD patients included in this study was very limited; therefore, further studies are mandatory to analyze the efficacy of one-stage implantation in AMI patients.

INTERMACS level 1 patients have variable end-organ function from end-stage failure to normal limit. Pre-existing renal dysfunction with a cutoff creatinine value of 1.96 mg/dL was an independent risk factor for early mortality after durable VAD implantation for patients at the INTERMACS level 1 [15]. Several studies have also reported on the relationship between renal function and mortality [16–19]. Although preoperative renal dysfunction can improve after LVAD implantation, patients in profound cardiogenic shock often require perioperative renal replacement therapy, resulting in prolonged ICU stay, increased risks of other complications, and eventual death. Early interventions to restore end-organ perfusion should be considered without delay. If renal function progressively declines despite optimal medical therapy, bridge-to-decision strategy might be considered to see reversibility of renal function. These patients often have simultaneous hepatic dysfunction. Hepatic dysfunction usually accompanies coagulation disorder and platelet dysfunction. The one-stage implantation of durable LVAD will bring the risk of intra- and postoperative bleeding complications in these patients. It would be reasonable to use the less invasive temporal MCS to avoid more invasive one-stage LVAD implantation in those with coagulopathy.

INTERMACS 1 patients usually have pulmonary edema due to an increase of pulmonary venous system pressure. Pulmonary edema can dramatically improve after left ventricular unloading by LVAD. However, for patients complicated with severe acute pulmonary injury, simultaneous implantation of a temporary right ventricular assist device (RVAD) with membrane oxygenator can be considered as an option [20].

Unknown neurological status is also a common complication in INTERMACS 1 patients because of their acuity of illness. In these patients, predicting the neurological prognosis in the acute phase is difficult, and it will usually take several days to weeks to recover. Unknown neurological status should be a contraindication for durable LVAD; thus, it is reasonable to bridge them with a short-term MCS before durable LVAD insertion.

Because of these baseline patient illnesses, mortality after primary LVAD implantation in INTERMACS 1 is significantly higher than that of patients in other INTERMACS profile [4]. The INTERMACS data showed 82, 76, and 58% of survival at 6, 12, and 36 months, respectively. The contributed hazard ratio of INTERMACS level 1 for early cause mortality was 1.55 in this report. The careful decision-making for one-stage implantation of durable LVAD for patients at the INTERMACS level 1 should be warranted considering high-risk patient profiles. The HeartMate II risk score (HMRS), which is calculated using patients’ age, albumin, serum creatinine, international normalized ratio (INR), and center volume, has been reported to be useful to predict the mortality after LVAD implantation in INTERMACS level 2 or more ambulant patients [21]. Recently, Adamo et al. reported that HMRS was also useful to predict the mortality of patients at the INTERMACS level 1 [22]. In this report, the 90-day mortality was 6.9%, 11.8%, and 39.1% in low, mild, and high HMRS groups, respectively. Considering these results, one-stage durable LVAD implantation might be a feasible option for patients in the low to mild HMRS groups within the INTERMACS level 1.