Intermacs annual feature
Sixth INTERMACS annual report: A 10,000-patient database

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The sixth annual report of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) summarizes the first 8 years of patient enrollment. The analysis is based on data from >10,000 patients and updates demographics, survival, adverse events and risk factors. Among patients with continuous-flow pumps, actuarial survival continues to be 80% at 1 year and 70% at 2 years. The report features a comparison of two eras of continuous-flow durable devices in the USA in terms of device strategy, patient profiles, adverse event burden, survival and quality of life.

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Patient and site enrollment

Between June 23, 2006 and June 30, 2013, 12,335 patients who received an FDA-approved durable mechanical circulatory support (MCS) device were entered into the INTERMACS database (Figure 1). Of the 158 participating hospitals, data were contributed by 141 centers that had also been approved for destination therapy (DT). The rate of accrual has continued at a pace exceeding 2,000 patients per year (Figure 1). Pediatric patients ≤18 years of age are now included in a separate database within

Approved adult devices

Table 1 lists the current FDA-approved MCS devices used in adult patients. The HeartMate II (Thoratec, Pleasanton, CA) continuous-flow pump was approved for bridge-to-transplant (BTT) therapy in 2008 and for DT in 2010. The HeartWare HVAD (HeartWare International, Inc., Framingham, MA) was approved for BTT indications on November 20, 2012.

Adult durable devices: Continued dominance of continuous-flow technology

The dominance of continuous-flow technology has been evident since 2008, and in the USA includes the HeartMate II axial-flow pump (BTT and DT) and the HeartWare HVAD centrifugal-flow pump (BTT). Continuous-flow pumps account for 100% of patients receiving DT since 2010 (Figure 3) and >95% of all patients receiving primary MCS implants (Figure 4).

PEDIMACS: Initial data collection

PEDIMACS, the pediatric component of INTERMACS, began data collection on September 1, 2012. Prior to that, patients <18 years of age were entered into INTERMACS with pediatric-specific data elements. Between September 1, 2012 and December 31, 2013, patients from 29 pediatric and/or combined pediatric/adult institutions were entered in the PEDIMACS database (Figure 5). This database includes 99 patients who received a durable MCS device and 19 patients who received temporary MCS devices

Device strategy

Mechanical circulatory support as a DT strategy2, 3 continues to represent a major proportion of overall implants. Comparing three eras of continuous-flow technology in the USA, the proportion of patients receiving a durable device as DT increased from 14.7% in 2006–2007 to 41.6% in 2011–2013 (Table 4). The proportion of patients actually listed for cardiac transplant at the time of implant decreased from 42.4% (2006 to 2007) to 21.7% (2011–2013). Examining just continuous-flow devices, the

Survival with continuous-flow pumps

Survival for continuous-flow devices through December, 2013 is shown in Figure 8 with the accompanying hazard function. The hazard function shows a rapidly decreasing early phase of risk that merges with a constant phase at about 3 months. We identified a late phase of gradually increasing risk out to 5 years. Comparing two eras of continuous-flow technology, survival has remained unchanged over the past 5 years (Figure 9). Actuarial survival at 1 and 2 years has reached 80% and 70%,

Updated risk factors for mortality

The updated risk factor analysis for continuous-flow pumps is shown in Table 6. The patient risk factors remained unchanged from our previous analysis in 2013.4 The moderate survival decrement among patients ≥65 years of age is shown in Figure 11. Patients implanted as INTERMACS Level5 1 and 2 continued to have worse survival (Figure 12). Compared with an earlier era, fewer patients have been receiving implants as Level 1 or 2, whereas the proportion of patients implanted in a stable,

Adverse events

As previously reported,6 adverse event rates with continuous-flow pumps have generally been dramatically lower than for previous pulsatile technology, particularly in the domains of device malfunction and infection. However, of greater current interest is the possibility that adverse events burden is decreasing with greater experience using continuous-flow devices. Table 8 compares adverse rates for earlier (2008–2010) versus later (2011–2013) eras of continuous-flow MCS therapy. Over a 6-year

Quality of life

The quality-of-life indicators out to 24 months post-implant are compared for the two eras using the EQ-5D Visual Analog Scale (Figure 17), self-care (Figure 18) and usual activities (Figure 19) dimensions. The quality-of-life improvements at 12 and 24 months have remained consistent over the past 6 years.

Survival impact of multiple pump replacements

The unusual need for pump exchange has a clearly detrimental effect on patient survival (Figure 20). One-year survival after the original continuous-flow implant is now about 80%, but about 65% after a second implant and 50% after a third implant. Thus, solutions to prevent pump malfunction and pump thrombosis are of great importance.

Time-related causes of mortality

The time-related risks for the major causes of death are depicted in Figure 21. During the early phase, the risk of multi-system organ failure mortality persists out to about 4 months before it merges with a constant hazard. After the first 3 months, neurologic causes of death have the greatest risk during the remainder of the first year. When extended out to 4 to 5 years, the gradually increasing late hazard for death from infection and multi-system organ failure is apparent (Figure 22).

Medical therapy

The medical arm of INTERMACS (MEDAMACS) was launched in January 2013. Data were collected on 70 patients in 12 hospitals, focusing on INTERMACS Levels 4 to 7, as depicted in Table 9. MEDAMACS tracks these patients and their changing profiles over time to assess survival, function, quality of life and eventual consideration of VAD for ambulatory heart failure in those considered “less sick” on recommended medical therapies.

Summary

  • 1.

    The INTERMACS database contains detailed demographic, survival, adverse events and other outcomes data on >10,000 patients.

  • 2.

    PEDIMACS and MEDAMACS are actively enrolling patients in each database.

  • 3.

    Continuous-flow technology continues to dominate adult durable implants, at a pace exceeding 2,000 implants per year.

  • 4.

    The need for inotrope therapy still largely defines the threshold for VAD therapy.

  • 5.

    Survival with continuous-flow pumps is about 80% at 1 year and 70% at 2 years, with no change in the

Disclosure statement

D.C.N. is a consultant for HeartWare and F.D.P. does contract research with HeartWare managed by the University of Michigan. J.K.K., R.L.K., L.W.S., M.A.M. and J.T.B. have no conflicts of interest to disclose.

This analysis and the INTERMACS device database are funded by a contract grant from the NHLBI (HHSN2682011000250).

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