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\begin{document}

\title{Response to Letter to the Editor: ``Impact of preoperative troponin
levels on cardiac function following coronary surgery for myocardial
infarction''}



\author[1]{Nicholas Hess}%
\author[2]{Arman Kilic}%
\affil[1]{University of Pittsburgh Medical Center}%
\affil[2]{Medical University of South Carolina}%


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  \date{May 24, 2024}


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\textbf{Response to Letter to the Editor: ``Impact of preoperative
troponin levels on cardiac function following coronary surgery for
myocardial infarction''}

Nicholas Hess MD\textsuperscript{1}, Arman Kilic MD\textsuperscript{2}

\emph{\textsuperscript{1}Division of Cardiac Surgery, University of
Pittsburgh Medical Center, Pittsburgh, PA}

\emph{\textsuperscript{2}Division of Cardiothoracic Surgery, Medical
University of South Carolina, Charleston, SC}

\textbf{Running Title:} Preoperative Troponin Before CABG

\textbf{Word Count:} 498

\textbf{Correspondence and Reprint Requests} :

Arman Kilic, MD

Division of Cardiothoracic Surgery

Medical University of South Carolina

30 Courtenay Drive, MSC 295, Suite BM279

Charleston, SC 29425

Email: kilica@musc.edu

Tel: 843-876-4841

Fax: 843-876-4866

We appreciate the thoughtful concerns and comments from Miyauchi and
colleagues to our manuscript titled ``Impact of preoperative troponin
levels on cardiac function following coronary surgery for myocardial
infarction''.\textsuperscript{1} Their commentary has highlighted
important limitations to our study that must be considered, as well as
the scope of which this study's results must be contextualized.

A key concern to this study made by Miyauchi \emph{et al} is the
definition assigned to ``peak'' troponin concentrations. As stated,
patients presenting with acute coronary syndrome often have few troponin
levels drawn prior to intervention. As such, the true troponinemia
curve, along with true troponin peak may not be captured. This study
analyzed pre-intervention troponin levels using the highest serum levels
recorded, which may not be representative of the ``true peak'' levels -
a limitation we have mentioned in our manuscript. Therefore, this
study's findings must be placed within the context of usual patient
care, which is, the highest troponin concentration collected prior to
surgical revascularization is largely unpredictive of short and
long-term outcomes. In order to definitively assess the impacts of
troponinemia upon postoperative outcomes, a protocolized method of
collecting serial troponin levels must be instituted in order to capture
the ``true peak'' on these patients. While such methods may best assess
these associations, they may also result in unwanted disruptions in the
usual conduct of patient care and introduce delays in revascularization.

Another valid concern of the authors is the exclusion of patients
without troponin elevation, which may dilute the implications of
troponin elevation. The presence of troponin elevation prior to coronary
revascularization, both percutaneous intervention and coronary artery
grafting, has been previously shown to be related to worse outcomes in
comparison to those without troponinemia.\textsuperscript{2--7} As this
relationship has been well established, we were largely interested in
evaluating the significance of the degree of troponin elevation among
those with pre-revascularization troponinemia. The authors have also
mentioned the importance of consideration of timing between onset of
acute coronary syndrome and surgical revascularization when evaluating
outcomes. Our models, both for postoperative mortality and major adverse
cerebrovascular and cardiovascular events (MACCE), were adjusted for the
peak troponin to surgical revascularization time interval.

Lastly, agree that long-term survival and MACCE are meaningful and
often-studied outcomes, but they do not tell the whole story. Long-term
echocardiographic data, as well as long-term heart failure readmission
and/or need for advanced heart failure therapies would be very important
to fully assess the long-term effects of troponin elevations.

\textbf{Disclosures and Conflicts of Interest}

Arman Kilic, MD is on the medical advisory board for Medtronic, Inc.
This affiliation is not in conflict with the contents of this letter

\textbf{References}

1. Miyauchi M, Imamura T. Letter to the Editor: Impact of Preoperative
Troponin Levels on Cardiac Function Following Coronary Surgery for
Myocardial Infarctoin. \emph{J Card Surg} . 2021.

2. Beller JP, Hawkins RB, Mehaffey JH, et al. Does Preoperative Troponin
Level Impact Outcomes After Coronary Artery Bypass Grafting? \emph{Ann
Thorac Surg} . 2018;106(1):46-51. doi:10.1016/j.athoracsur.2018.01.085

3. Lyon WJ, Baker RA, Andrew MJ, Tirimacco R, White GH, Knight JL.
Relationship between elevated preoperative troponin T and adverse
outcomes following cardiac surgery. \emph{ANZ J Surg} .
2003;73(1-2):40-44. doi:10.1046/j.1445-2197.2003.02611.x

4. Giannitsis E, M\selectlanguage{ngerman}üller-Bardorff M, Lehrke S, et al. Admission troponin
T level predicts clinical outcomes, TIMI flow, and myocardial tissue
perfusion after primary percutaneous intervention for acute ST-segment
elevation myocardial infarction. \emph{Circulation} .
2001;104(6):630-635. doi:10.1161/hc3101.093863

5. Matetzky S, Sharir T, Domingo M, et al. Elevated Troponin I Level on
Admission Is Associated With Adverse Outcome of Primary Angioplasty in
Acute Myocardial Infarction. \emph{Circulation} .
2000;102(14):1611-1616. doi:10.1161/01.CIR.102.14.1611

6. Heidenreich PA, Alloggiamento T, McDonald KM, Go AS, Hlatky MA,
Melsop K. The prognostic value of troponin in patients with non-ST
elevation acute coronary syndromes: a meta-analysis. \emph{J Am Coll
Cardiol} . 2001;38(2):478-485. doi:10.1016/S0735-1097(01)01388-2

7. Paparella D, Scrascia G, Paramythiotis A, et al. Preoperative Cardiac
Troponin I to Assess Midterm Risks of Coronary Bypass Grafting
Operations in Patients With Recent Myocardial Infarction. \emph{Ann
Thorac Surg} . 2010;89(3):696-702. doi:10.1016/j.athoracsur.2009.11.072

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