Corresponding author
Michele Di Mauro, MD, PhD, MSc Biostat.
Cardiologist and Cardiac Surgeon
Research Fellow
Cardio-Thoracic Surgery Unit,
Heart and Vascular Centre,
Maastricht University Medical Centre (MUMC),
Cardiovascular Research Institute Maastricht (CARIM),
P. Debyelaan 25, 6202 AZ
Maastricht, The Netherlands
Email:mdimauro1973@gmail.com
Abstract
It is well known that the left internal mammary artery (LIMA) should be
the first conduit of choice. Similarly, especially in patients younger
than 70 years, other conduits should be search among arterial grafts
such as right internal mammary artery (RIMA) or radial artery (RA). If
the RA can be harvested in the meanwhile of LIMA harvesting without time
consuming, it is well established that former one has to be grafted only
on presence of a good run-off. One of the main criticisms moved to the
use of RIMA are linked to technical difficulties in its harvesting it.
Edgar Aranda-Michel and coworkers tried to answer to the age-old
question is “RIMA has to be used in situ or free-graft?” In a
retrospective study on 667 patients (442 had free RIMA and 245 had free
RIMA) that were also matched through propensity analysis (202 patients
per group), they did not find any differences between the two groups in
the major outcomes, including heart failure specific readmissions. This
finding is consistent with the literature, hence the take-home message
is whatever happens, two mammary is better than one.
Coronary artery bypass grafting (CABG) is the most commonly performed
surgery on the heart up to these days. Nevertheless, there are still
many controversies on what is best way to perform it. It is well known
that the left internal mammary artery (LIMA) should be the first conduit
of choice. Similarly, especially in patients younger than 70 years,
other conduits should be search among arterial grafts such as right
internal mammary artery (RIMA) or radial artery (RA) [1-3].
However, one of the main criticisms moved to the use of RIMA are linked
to technical difficulties in its harvesting it. Indeed, some authors
advised to start using RA, and only after gaining enough experience with
it, surgeons can move to RIMA grafting [3].
But, is it fully true? If the RA can be harvested in the meanwhile of
LIMA harvesting without time consuming, it is well established that
former one has to be grafted only on presence of a good run-off (i.e.
severe target coronary stenosis, wide vessel territory, no myocardial
infarction) [4]. On the other hand, RIMA should preferably be
harvested in a skeletonized fashion, to decrease the risk of sternal
wound infection [5], and this is surely more technically demanding.
Moreover, some authors recommend to use RIMA in situ at the beginning,
since it could be easier than perform Y or T graft [5]. Hence, the
age-old question is “RIMA has to be used in situ or free-graft?”
Edgar Aranda-Michel et al.[6] tried to answer to this question by
performing a retrospective study on 667 patients (442 had free RIMA and
245 had free RIMA) that were also matched through propensity analysis
(202 patients per group). They did not find any differences between the
two groups in the major outcomes, including heart failure specific
readmissions. They only found that the an in-situ RIMA anastomosis was
protective against heart failure readmission, even if the authors
[6] blame a possible bias of selection, in which the free RIMA were
initially more commonly used in more ischemic heart. Indeed, the results
is lost when propensity match analysis is applied.
Their results are in line with some previously published literature. Di
Mauro et al.[7] also performed a propensity analysis and found no
differences between the configuration of RITA. Nevertheless, other
authors [8] suggest the opposite, meaning that a free RITA gave
worse long term results regarding cardiovascular mortality. They
suggested that an additional anastomosis might be responsible, by
causing a drop of pressure at the distal anastomosis because of a longer
arterial configuration, especially in case of Y assembly.
In such a complicated scenario, Edgar Aranda-Michel et al.[6]
provided a further piece of evidence in a field where lacks
standardization, little experience and fear of wound infections
[9-10] are limiting the use of RITA. Hence, the study by Edgar
Aranda-Michel et al.[5] might encourage younger surgeons to embrace
the use of RITA, having the confidence to use it both in-situ and as a
free graft. Of course, attention must by taken to the site of the
anastomosis: it is better to avoid a Y graft to two different
territories (left vs right coronary) because of the different driving
pressures and for sure further studies are needed to understand the best
application of CT Scan and Coronary angiography, to get as many
information as possible on the real amount of stenosis.
Indeed, the danger of the Y graft is also related to a coronary
functional reserve that is perceived lower than actually is [11].
Gaudino et al [12] performed a intra-operative flowmetry study,
showing as Y graft is more than enough to assure the appropriate flow in
each branch.
So why should we read the paper by Edgar Aranda-Michel et al.[6]? It
elegantly demonstrates the absence of difference between two different
configuration of RITA, overcoming the doubt of many surgeons on the use
of RITA. Hence, the take-home message is whatever happens, two
mammary is better than one.
REFERENCES
[1] L David Hillis, Peter K Smith, Jeffrey L Anderson, John A Bittl,
Charles R Bridges, John G Byrne, Joaquin E Cigarroa, Verdi J Disesa,
Loren F Hiratzka, Adolph M Hutter Jr, Michael E Jessen, Ellen C Keeley,
Stephen J Lahey, Richard A Lange, Martin J London, Michael J Mack,
Manesh R Patel, John D Puskas, Joseph F Sabik, Ola Selnes, David M
Shahian, Jeffrey C Trost, Michael D Winniford, American College of
Cardiology Foundation; American Heart Association Task Force on Practice
Guidelines; American Association for Thoracic Surgery; Society of
Cardiovascular Anesthesiologists; Society of Thoracic Surgeons. 2011
ACCF/AHA Guideline for Coronary Artery Bypass Graft Surgery. A report of
the American College of Cardiology Foundation/American Heart Association
Task Force on Practice Guidelines. Developed in collaboration with the
American Association for Thoracic Surgery, Society of Cardiovascular
Anesthesiologists, and Society of Thoracic Surgeons. J Am Coll Cardiol
2011;58: 2584–614.
[2]Chikwe J, Sun E, Hannan EL, Itagaki S, Lee T, Adams DH, Egorova
NN. Outcomes of Second Arterial Conduits in Patients Undergoing
Multivessel Coronary Artery Bypass Graft Surgery. J Am Coll Cardiol.
2019 Nov 5;74(18):2238-2248. doi: 10.1016/j.jacc.2019.08.1043. PMID:
31672179.
[3] Gaudino MFL, Sandner S, Bonalumi G, Lawton JS, Fremes SE;
Coronary Task Force of the European Association for Cardio-Thoracic
Surgery. How to build a multi-arterial coronary artery bypass programme:
a stepwise approach. Eur J Cardiothorac Surg. 2020 Dec
1;58(6):1111-1117. doi: 10.1093/ejcts/ezaa377. PMID: 33247735; PMCID:
PMC7824806.
[4] Gaudino M , Taggart D , Suma H , Puskas JD , Crea F , Massetti
M. The choice of conduits in coronary artery bypass surgery. J Am Coll
Cardiol 2015;66:1729–37.
[5] Zhou P, Zhu P, Nie Z, Zheng S. Is the era of bilateral internal
thoracic artery grafting coming for diabetic patients? An updated
meta-analysis. J Thorac Cardiovasc Surg. 2019 Dec;158(6):1559-1570.e2.
doi: 10.1016/j.jtcvs.2019.01.129. Epub 2019 Feb 23. PMID: 30952540.
[6] Aranda-Michel E, Serna-Gallegos D, Navid F, Kilic A, Williams
AA, Garcia R, Bianco V, Brown JA,
Sultan I. The Use of Free vs In-Situ Right Internal Mammary Artery in
Coronary Artery Bypass Grafting. J Card Surg 2021 in press
[7] Di Mauro M, Iacò AL, Allam A, Awadi MO, Osman AA, Clemente D,
Calafiore AM. Bilateral internal mammary artery grafting: in situ versus
Y-graft. Similar 20-year outcome. Eur J Cardiothorac Surg. 2016
Oct;50(4):729-734. doi: 10.1093/ejcts/ezw100. Epub 2016 Mar 25. PMID:
27016198.
[8] Marzouk M, Kalavrouziotis D, Grazioli V, Meneas C, Nader J,
Simard S, Mohammadi S. Long-term outcome of the in situ versus free
internal thoracic artery as the second arterial graft. J Thorac
Cardiovasc Surg. 2020 Mar 13:S0022-5223(20)30549-3. doi:
10.1016/j.jtcvs.2020.03.003. Epub ahead of print. PMID: 32305200.
[9] LaPar DJ, Crosby IK, Rich JB, Quader MA, Speir AM, Kern JA,
Tribble C, Kron IL, Ailawadi G; Investigators for the Virginia Cardiac
Surgery Quality Initiative. Bilateral Internal Mammary Artery Use for
Coronary Artery Bypass Grafting Remains Underutilized: A
Propensity-Matched Multi-Institution Analysis. Ann Thorac Surg. 2015
Jul;100(1):8-14; discussion 14-5. doi: 10.1016/j.athoracsur.2015.02.088.
Epub 2015 May 20. PMID: 26002440.
[10] Calafiore AM, Iacò AL, Di Mauro M. Spending 30 minutes to add
years to a patient’s life: Why is the last step so difficult? J Thorac
Cardiovasc Surg. 2015 Aug;150(2):321-2. doi:
10.1016/j.jtcvs.2015.05.018. Epub 2015 May 9. PMID: 26099367.
[11] Botman CJ, Schonberger J, Koolen S, Penn O, Botman H, Dib N et
al. Does stenosis severity of native vessels influence bypass graft
patency? A prospective fractional flow reserve-guided study. Ann Thorac
Surg 2007;83: 2093–7
[12] Gaudino M, Di Mauro M, Iacò AL, Canosa C, Vitolla G, Calafiore
AM. Immediate flow reserve of Y thoracic artery grafts: an
intraoperative flowmetric study. J Thorac Cardiovasc Surg. 2003
Oct;126(4):1076-9. doi: 10.1016/s0022-5223(03)00122-3. PMID: 14566250.