INTERMACS Annual Report
Seventh INTERMACS annual report: 15,000 patients and counting

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The seventh annual report of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) summarizes the first 9 years of patient enrollment. The Registry includes >15,000 patients from 158 participating hospitals. Trends in device strategy, patient profile at implant and survival are presented. Risk factors for mortality with continuous-flow pumps are updated, and the major causes/modes of death are presented. The adverse event burden is compared between eras, and health-related quality of life is reviewed. A detailed analysis of outcomes after mechanical circulatory support for ambulatory heart failure is presented. Recent summary data from PediMACS and MedaMACS is included. With the current continuous-flow devices, survival at 1 and 2 years is 80% and 70%, respectively.

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Patient and site enrollment

Between June 23, 2006 and December 31, 2014, 15,745 patients who received a U.S. Food and Drug Administration (FDA)-approved MCS device were entered into the INTERMACS database. Of the 158 participating hospitals, 123 (78%) were certified by the Joint Commission for destination therapy (DT). The rate of patient enrollment has continued at a pace exceeding 2,000 patients per year. Of the 12,030 patients who received a CF device, >90% received a left ventricular assist device (LVAD) only (Figure 1

Device strategy

The progressive increase in VADs implanted for DT, evident between 2008 and 2013, plateaued in 2014, with nearly 46% of implants designated as DT (Table 2). Thirty percent of patients were listed for heart transplantation at the time of device implant, and an additional 23% were implanted with an anticipated possibility of listing (“bridge to candidacy”).

By competing outcomes analysis, about 30% of patients have undergone heart transplantation within 1 year if listed at time of implant (Figure 3

Patient profile at implant

The proportion of patients in cardiogenic shock at the time of implant has remained stable at about 15% since 2008 (Table 3). The proportion of patients in INTERMACS Level II or III remains at about 65%. Patients with ambulatory heart failure comprise about 20% of implants.

Survival with CF pumps

The updated survival curve for CF devices implanted since 2008 shows an overall 1-year survival of 80% and 2-year survival of 70% (Figure 5). Survival with biventricular VAD (BiVAD) support has remained inferior to that of isolated LVAD (Figure 6). In the most recent era, only about 50% of patients are alive with BiVAD support at 1 year. Survival with axial-flow and centrifugal-flow pumps, unadjusted for risk, is depicted in Figure 7. Early and mid-term survival with a total artificial heart is

Risk factors for mortality with CF technology

Table 4 lists the updated risk factors for mortality with CF devices through December 2014. Type of CF pump was not a risk factor for mortality. The updated stratified actuarial depictions to illustrate the effect of each risk factor can be found on the INTERMACS website (www.intermacs.org). Survival among DT patients has continued to be somewhat worse than among BTT patients, and this relationship has not changed very much over time (Figure 9). In the most recent era, survival with DT therapy

Causes/modes of death

The hazard functions for the major causes/modes of death are depicted in Figure 10. Neurologic events, right heart failure and multisystem organ failure are the predominant causes or modes of death early after implantation, whereas infection, multiorgan system failure and neurologic events are the major causes/modes of late mortality. In this analysis, the risk of death from device malfunction appears to be low and constant over time.

Adverse events

In Table 5, adverse event rates during the first year after implant are depicted for 2 eras. The overall adverse event burden is significantly lower in the most recent era. However, increasing event rates can be observed for hemolysis, stroke, renal dysfunction and respiratory failure.

Pump exchange

The complex issue of pump thrombosis for the HeartMate II device has been extensively reported elsewhere.2, 3 The overall rate of pump exchange for any reason for all CF pumps has continued to be somewhat higher in the more recent era. Of importance, the decrement in survival after each subsequent pump exchange is evident (Figure 11).

Quality of life

The EQ-5D Visual Analog Scale (VAS) and determination of specific dimensions continue to be the mainstay of our health-related quality of life (HRQOL) assessment. The trend of early, substantial improvement in these HRQOL indicators (Figure 12, Figure 13, Figure 14) has been maintained out to 2 years. There continues to be little difference by era.

MCS for ambulatory heart failure

In the INTERMACS classification, Levels 4 to 7 describe ambulatory advanced heart failure.4 The difficulty in obtaining accurate information on this patient group is underscored by our finding that only about 20% of implants occur in patients with ambulatory heart failure (see Table 3). Early and mid-term survival among patients at Level 1 continues to be significantly worse than for less sick profiles. However, survival in Levels 2 and 3 is nearly superimposable on the survival curve for

PediMACS

The pediatric component of INTERMACS began collecting all pediatric data (patients <19 years of age) in September 2012. Through April 2015, 36 centers have enrolled 251 devices in 216 patients (Figure 23). The durable and temporary mechanical circulatory devices that have been entered into the Registry are included in Table 8.

During the period September 19, 2012 through December 31, 2014, among patients up to 5 years of age, pulsatile LVADs (Berlin Heart EXCOR; Berlin Heart Steglitz, Berlin,

MedaMACS

Since December 2012, MedaMACS, the medical arm of INTERMACS, has focused on data collection in ambulatory heart failure patients who have not received a durable MCS device at the time of entry into the Registry. The distribution of the 154 patients enrolled into MedaMACS is predominantly in INTERMACS Levels 5 and 6 (Table 10). VAD/transplant-free survival at 12 months has approached 75%.

Summary

  • The INTERMACS database now exceeds 15,000 patients, with total implants approaching 2,500 per year.

  • The 1- and 2-year survival with CF pumps is currently 80% and 70%, respectively.

  • DT accounts for nearly half of all implants.

  • Approximately one third of adult VAD patients receive a heart transplant by 1 year.

  • Fifteen percent of all patients are implanted as INTERMACS Level 1.

  • BiVAD support continues to be associated with 50% mortality at 1 year.

  • Pump exchange is associated with a major reduction in

Disclosure statement

D.C.N. is a consultant for HeartWare and F.D.P. participates in contract research managed by the University of Michigan for HeartWare and Thoratec. The remaining authors have no conflicts of interest to disclose. This analysis and the INTERMACS device database are funded by a contract grant (HHSN2682011000250) from the National Heart, Lung and Blood Institute.

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