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Second INTERMACS annual report: More than 1,000 primary left ventricular assist device implants

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Patient population

Between June 23, 2006, and March 31, 2009, 88 institutions (Appendix 1) entered 1,420 patients into the INTERMACS database. Mean follow-up for survivors has been 6 months (range, 1 day to 2.9 months).

This report will focus on the 1,092 patients who received primary left ventricular assist device (LVAD) implants among the total of 1,420 patients who received primary and secondary devices (Table 1). The FDA-approved devices included in the INTERMACS registry are listed in Appendix 2. The general

Device type, severity of illness, and pre-implant strategy

The 1,092 primary LVAD implants were approximately 48% pulsatile and 52% continuous flow pumps (Table 3). At the time of implant, 85% of patients were in INTERMACS level 1 or 2 or 3, and less than 5% were higher than level 4 (Table 4).3 The spectrum of INTERMACS levels has changed during the course of the study; the proportion of level 1 has decreased from 38% during the first half of the study to 27% during the second half. This likely reflects a recognition of the higher early mortality

Survival

The superior survival of LVAD patients compared with survival with device types and combinations in this database is reflected in Figure 1. The focus of this report is the actuarial survival of the primary LVAD cohort, which was 83% at 6 months, 74% at 1 year, and 55% at 2 years (Figure 2).

The survival stratified by INTERMACS levels shows early increased death for patients in level 1 at the time of device implant (Figure 3). When stratified by device strategy, BTT patients had superior survival

Causes of death

The primary causes of death for patients receiving primary LVAD implants are listed in Table 7. The major causes of death differed somewhat according to device strategy: central nervous system events accounted for nearly twice the proportion of deaths among DT patients as for BTT or BTC patients (Table 8). The reasons for this difference are not yet apparent.

Risk factors for death

By multivariable analysis, (see Appendix 3 for list of variables examined), risk factors reflecting older age, greater severity of right ventricular failure, and cardiogenic shock at implant predict a higher likelihood of early death among all LVAD patients (Table 9). It is of interest that the use of a pulsatile pump was a risk factor for death in the constant phase. Whether pump-related complications or malfunction account for this risk factor will require further analyses. Among the smaller

Emergence of continuous flow technology

During the first 2 years of INTERMACS, few pulsatile pumps were entered into the registry. With the first FDA approval of a continuous flow pump for adults as BTT support in April 2008, these pumps became available for entry into INTERMACS. Patient accrual before and after approval of an adult continuous flow pump shows a dramatic change in favor of continuous flow devices (Figure 8). The preference for continuous flow technology as BTT therapy (currently no continuous flow pump is approved for

Adverse events

The profile of adverse events among primary LVAD patients is listed in Table 11. Because continuous flow pumps have only accrued a mean follow-up of 4.6 months, Table 12 compares adverse events among pulsatile vs continuous flow pumps during the first 6 months after implantation. Infection and bleeding remain the most common adverse events in the LVAD population in the first year after implant. In the BTT and BTC groups, the adverse events are different for the continuous vs pulsatile pumps. In

Evolution of device strategy

The frequency with which patients are diverted from their original strategy was documented in the first annual INTERMACS report.1 Coincident with the availability of a continuous flow pump for BTT in adults in April 2008, a marked shift occurred away from a primary strategy of DT among patients entered into the registry (Table 13). The dramatic increase in the number of patients entered into the database with a primary strategy of BTT or BTC beginning in the second quarter of 2008 (Table 13)

Areas of incomplete data submission

Although INTERMACS requires strict adherence to data submission, identification of adverse events, and complete patient follow-up, the registry does not directly mandate specific clinical protocols for frequencies of routine patient visits, laboratory tests to be obtained, or functional outcomes and quality of life tests to be administered. However, INTERMACS does require that if any such tests are obtained, the results must be entered.

The divergence in clinical practice for routine chemistries

Summary

INTERMACS has analyzed the first 1000-plus patients with primary implantation of LVADs during a transitional period from pulsatile technology to continuous flow pumps. The shift toward implantation of axial flow technology since its approval by FDA is dramatic. This trend has been accompanied by continued fluctuation in the designation of primary device strategy as BTT, BTC, and DT. Inferences from this database regarding expected midterm survival with device therapy must be interpreted with

Disclosure statement

This work was sponsored by the National Institutes of Health, National Heart, Lung and Blood Institute (NHLBI), Registry of Mechanical Circulatory Support Devices for End-Stage Heart Failure (INTERMACS). Contract No. HHSN268200548198C.

None of the authors has a financial relationship with a commercial entity that has an interest in the subject of the presented manuscript or other conflicts of interest to disclose.

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    Citation Excerpt :

    In 2009, INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) reported that from 2006 to 2009, across 89 participating hospitals, only 1420 individuals were implanted with LVADs for any purpose.25 The survival rate was 83% at 6 months, 74% at a year, and 55% at 2 years.25 Five years later, INTERMACS reported in 2014 that 1108 individuals, or about 46% of those implanted, received LVAD-DT across 158 participating medical centers.6

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