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INTERMACS Database for Durable Devices for Circulatory Support: First Annual Report

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Background

With primary funding and oversight provided by the NHLBI, the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) was established to advance the understanding and application of mechanical circulatory support in order to improve the duration and quality of life for individuals with advanced heart failure. The term “Interagency” emphasizes the unique collaboration of the NHLBI as the funding and scientific support agency, the FDA as the regulatory agency, and the

Shared Goals for the Interagency Registry

The goals of the registry, as listed in Table 1, underscore its fundamental mission to investigate, facilitate, and improve the application of mechanical circulatory support as a long-term therapy to improve the duration and quality of life for patients with advanced heart failure. The research spectrum extends from gaining new understanding of mechanisms of heart failure decompensation to the science of circulatory support and myocardial recovery, a key initiative for the NHLBI. Mechanical

INTERMACS Design and Structure

Principle design features of the INTERMACS database include the participation of a wide range of experts from cardiology, surgery, nursing, engineering, and device development sciences. The open committee structure (Figure 1) reflects individual broad expertise, with representatives from each committee providing updates and agenda items for regular Operations Committee meetings. Shared access to the overall data obtained, after specific site and device identifiers are removed, is available to

Requirement for Site Participation in INTERMACS

INTERMACS participation will meet the CMS and Joint Commission on Accreditation of Healthcare Organizations (JCAHO) reporting requirement that all centers certified to implant destination therapy (DT) devices submit ventricular assist data to a national audited mechanical circulatory support registry. For all US institutions implanting mechanical circulatory support systems as permanent (destination) therapy, participation in INTERMACS is a requirement for reimbursement through CMS (Medicare).

Patient Device Enrollment

The INTERMACS registry went live on June 23, 2006. As of December 31, 2007, 89 hospitals were activated and able to enroll patients into the INTERMACS database. An additional 21 hospitals were pending activation. The total accrued patients entered into the database through December 31, 2007, include 511 patients from 75 institutions.

Patient Demographics

Among the 420 patients undergoing a mechanical circulatory support device implant between June 23, 2006, and December 31, 2007, male gender accounted for 78% of patients. The most common race was Caucasian (72%), followed by African American (20%). The majority of patients (51%) were aged 40 to 59, 29% were aged 60 to 79, 18% were aged 19 to 39, and only 2% were age 18 or younger.

Intermacs Patient Profiles

The INTERMACS heart failure profiles are detailed in the accompanying manuscript in this issue entitled, “INTERMACS Profiles of Advanced Heart Failure” by Stevenson and colleagues. The 7 INTERMACS levels are summarized in Table 4. The distribution of heart failure profiles at the time of implant is tabulated in Table 5. It is noteworthy that 44% of patients were in critical cardiogenic shock at the time of device implant.

Device Strategy

Durable mechanical circulatory support is currently used for 3 basic indications: bridge to transplantation (BTT), bridge to recovery, and long-term or destination therapy (DT). The distribution of device strategy at the time of implant is contained in Table 6. In addition to patients actually listed for cardiac transplantation, three other subcategories are also identified: BTT–likely, BTT–moderate, and BTT–unlikely to be listed. For purposes of this report, these 3 sub-categories have been

Survival

The actuarial survival for the entire cohort was 90% at 1 month and 56% at 1 year (Figure 3.). Among patients who required isolated left ventricular support (LVAD), the survival was particularly favorable at 67% at 1 year (Figure 4), censoring at time of transplant. When comparing device strategies, the survival out to 12 months was similar for the 3 major strategies (Figure 5). One-year actuarial survival for DT patients was 61%. Patients in the most critical condition at implant experienced

Outcomes After BTT

A competing outcomes analysis for BTT patients (Figure 8) shows 17% mortality at 6 months, with nearly 51% of patients receiving a heart transplant within 6 months. Among BTT patients, 56% of patients either received a transplant or were active on the transplant list at 6 months post-implant (Figure 9).

Outcomes After BTC

Bridge to candidacy describes a divergent patient population with sufficient comorbidities or incomplete evaluation that prevents active listing. Actual mortality on device support in this cohort was 26% at 6 months (Figure 10). At 3 and 6 months, 36% and 23% of patients, respectively, remained alive and unlisted (Figure 11).Table 11 lists the most common reasons preventing transplant listing at these time points.

Outcomes After Destination Therapy

Patient survival after DT implant is depicted in Figure 12. Despite the initial intent of permanent device therapy, 6% of this group had either undergone transplantation or was listed for transplantation by 3 months, increasing to 12% by 6 months (Figure 13).

Adverse Events

The definitions of adverse events reported here are detailed in the accompanying article by Kormos and colleagues. The 17 major adverse events identified through INTERMACS are listed in Table 3. Table 12 separates the major adverse events into those before and after 30 day. Bleeding and infection were the most common adverse events, both early and later. The risk of early bleeding was more than over 25% within the first month (Figure 14) Time-related freedom from infection is depicted in Figure

Summary

INTERMACS has completed the analysis of first full year of data on FDA-approved durable VADs. To date, nearly all approved devices are pulsatile volume-displacement pumps. As newer rotary pumps gain FDA approval, they will become a vital part of the INTERMACS experience and analyses. Overall survival after device implant exceeds 70% at 6 months, but is superior with isolated LVAD compared with bi-VAD support. The initial “strategy” at implant has no discernible effect on survival, and the

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This work was supported by National Institutes of Health Contract No. HHSN268200548198C.

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