CardioExchange Archive

CardioExchange, an NEJM practice community for medical professionals dedicated to improving cardiac patient care, was active from 2009 to 2015. CardioExchange fostered discussion between clinicians from across the globe.

November 7th, 2013

Internal Mammary Artery Grafting During CABG: How Common, How Effective?

CardioExchange’s John Ryan interviews Mark A. Hlatky about his research group’s analysis of the prevalence and effectiveness of internal mammary artery grafting during CABG procedures performed in Medicare patients. The study is published in JACC.

THE STUDY

In a study of Medicare beneficiaries aged ≥66 years who underwent isolated multivessel CABG from 1988 to 2008, researchers used a multivariable propensity score to match patients with and without an IMA graft (more than 60,000 patients in all, median follow-up of 6.8 years). IMA use rose from 31% of CABG procedures in 1988 to 91% in 2008. Rates of all-cause mortality, MI, and repeat revascularization were significantly lower in patients who underwent IMA grafting than in those who did not.

THE INTERVIEW

Ryan: Using Medicare claims data, you show that IMA use for patients undergoing CABG has increased and is associated with better outcomes. Are you confident about the coding of IMA use in administrative claims?

Hlatky: The coding of procedures is, in general, pretty accurate because of the close tie to billing for surgery. So I think the IMA codes are good here.

Ryan: Why do some surgeons not use an IMA? In 2008, only 8% of patients did not have an IMA.

Hlatky: Early on, I don’t think that all surgeons were convinced an IMA was necessary, and it certainly increased the length and difficulty of the procedure. Once using an IMA became a quality measure, nowadays I think there is a definite “intention to treat” with an IMA during CABG, if technically feasible.

Ryan: Was lack of IMA use a marker for surgeons with worse performance? How did you isolate the effect of the surgeon?

Hlatky: We were not able to examine individual surgeons and their use of IMAs. That’s the next step.

Ryan: Given your findings, are you or your group doing anything to improve IMA use?

Hlatky: Our study was more of a look back at a historical pattern of adoption, to gain some insight into the reasons for delayed adoption. Use of the IMA during CABG is now tracked, and there is relatively little room for improvement. Our study does suggest that surgical techniques may be adopted slowly, especially without an external push. Clinical trials are a major factor in spurring translation of findings into practice, and we have essentially no trials of IMA grafting.

JOIN THE DISCUSSION

Share your observations about the use of IMA grafting at your institution.

Categories: Cardiac Surgery
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2 Responses to “Internal Mammary Artery Grafting During CABG: How Common, How Effective?”

  1. David Powell , MD, FACC says:
    November 7, 2013 at 11:00 pm

    Was bilateral IMA use analyzed? Should this be a “quality” indicator?

  2. Mark Perlroth Mark, md says:
    November 9, 2013 at 4:40 pm

    THE BRIEF INTERVIEW YOU CONDUCTED WITH DR HLATKY NEVERTHELESS HIGHLIGHTED AN EXTREMELY IMPORTANT OBSERVATION RE THE SUPERIORITY OF IMA GRAFTING DURING CABG.

    AS A FELLOW FACULTY MEMBER WITH DR HLATKY AT STANFORD FOR MANY YEARS I WOULD UNDERLINE THE CAREFULNESS OF HIS DATA COLLECTION AND MY CONFIDENCE IN THE ACCURACY OF HIS FINDINGS.

    (I SUPPOSE THIS ALSO RAISES THE POSSIBILITY OF CONFLICT OF INTEREST. I ASSURE YOU THAT I HAVE HAD NO DIRECT CONTACT WITH DR HLATKY FOR THE PAST 5 YEARS.)