In the present study, we investigated whether
the detection of fQRS complexes on ECG in
preoperative evaluations of patients undergoing
elective CABG was a predictor to determine
postoperative cardiac status, short-term prognosis,
and mortality. Our study results showed that the
duration of CPB (p=0.017), the number of CABG
(p=0.026), length of ICU stay (p=0.020), and length
of hospital stay (p=0.010) in the fQRS+ group were
statistically significantly higher, while preoperative
LVEF values were statistically significantly lower
(p<0.001). The increase at the postoperative third
month in the LVEF values in these patients was
statistically significant (p<0.001). However, there
was no statistically significant difference between
the neutrophil/lymphocyte and hs-CRP values in
the fQRS+ group. Hypertriglyceridemia, diabetes
mellitus, and hypertension were not statistically
significantly different between the groups.
Additionally, no statistically significant difference
was observed in the rate of POAF, the most common
arrhythmia after CABG. The prevalence of fQRS
was more common in male patients in our study,
whereas increasing age and BMI did not affect the
prevalence of fQRS.
Coronary artery bypass grafting is frequently
utilized in the treatment of CAD.[8] Although
long-term survival is satisfactory after CABG,
arrhythmia, need for recurrent myocardial
revascularization, cerebrovascular events, sudden
death and heart failure may be encountered in
approximately one-third of patients in the postoperative follow-up.[9-11] The presence of
preoperative fQRS is frequently associated with
decreased myocardial contractility and multiple
coronary artery occlusions, as evidenced by a
decrease in LVEF.[12] It has been shown that patients
with preoperative fQRS have significantly lower
LVEF values.[13-15] In addition, unlike previous
studies, the increase in LVEF at three months after
CABG in patients with fQRS+ was statistically
significant in our study. Neutrophil/lymphocyte,
platelet/lymphocyte, and eosinophil/lymphocyte
ratios, and hs-CRP in patients with fQRS+
provided valuable data, particularly following
acute coronary syndrome.[16,17] In our study, there
was no statistically significant difference in the
rate of activated neutrophils, which are the first
and most commonly detected white blood cell
subtype in damaged myocardial tissue in patients
with fQRS, and furthermore lymphocyte count
were not also quantifying a diagnostic accuracy,
either. Furthermore, there were no significant
changes in hs-CRP values, platelet/lymphocyte and
eosinophil/lymphocyte ratios in our study.
Postoperative new-onset atrial fibrillation, the
most common arrhythmia after CABG, is observed
in nearly 10 to 40% of cases.[18] Early and late
postoperative POAF increases morbidity.[19] The first
study in the literature on the presence of preoperative
fQRS to be a significant risk factor for new-onset
POAF after CABG was published by Çetin et al.[20]
Also, Keskin and Kurtul[21] showed that POAF
rate and in-hospital mortality rate were higher in
patients with fQRS. However, our study indicates
that the presence of preoperative fQRS does not have
a statistically significant effect on the development of
new-onset POAF.
The QRS fragmentation may be an indicator of
early myocardial injury preceding the appearance of
fibrosis and scar, and may be used for risk stratification
in patients with CAD.[22] Considering the link between
multiple critical CAD and fQRS, the increase in the
number of CABG and the consequently prolonged CPB
durations have gained importance. We consider that
revascularization of patients with fibrosis secondary
to myocardial ischemia and detection of fQRS in
which scar formation is etiologically prominent should
be treated with CABG. Preoperative 12-lead ECG
is an important diagnostic method in determining
morbidity and mortality after CABG. The effects of
rhythm disturbances such as long QT interval, T wave alternance, P wave dispersion and atrial fibrillation,
which can be detected by 12-lead ECG, on mortality
and morbidity after CABG have been investigated
in the literature.[23-25] However, short- and long-term
effects of fQRS on morbidity and mortality after
CABG have not been examined thoroughly, paving
the way for us to conduct the current study. Based on
these results, the presence of fQRS is an important
marker of morbidity and mortality in post-CABG due
to inter- and intraventricular conduction abnormalities
secondary to myocardial fibrosis.
The single-center, retrospective design of this
study is the main limitation. Although our results
showed that fQRS could be a predictor for short-term
outcomes, further long-term studies are needed to
elucidate the effects of the presence of preoperative
fQRS on postoperative course following CABG.
In conclusion, the QRS fragmentation on a
12-lead surface ECG has recently gained increasing
attention as a simplified non-invasive ECG marker
with diagnostic and prognostic value in CAD. It
is a very simple method to evaluate patients who
are scheduled for elective CABG with a significant
predictor in terms of morbidity and mortality that
may be encountered in the early postoperative
period. Detection of QRS fragmentations is also
a cost-effective method to identify patients who
would need close follow-up and treatment in the
postoperative period. With the detection of fQRS in
patients to be treated with elective CABG, patient
groups at a higher risk category can be identified.
Patients with fQRS regarding fibrosis secondary to
myocardial ischemia should be treated with CABG.
The QRS complex fragmentations detected on ECG
at the time of initial admission may be useful to
identify patients at high cardiovascular risk who
would need closer follow-up and treatment after
CABG.
Ethics Committee Approval: This was a retrospective
and single-center study which was approved by the
Medicana International Istanbul Hospital Ethics Committee
(date: 12.08.2022, no: 2022/041) and was conducted in
accordance with the Declaration of Helsinki (as revised in
2013).
Patient Consent for Publication: A written informed
consent was obtained from each patient.
Data Sharing Statement: The data that support the
findings of this study are available from the corresponding
author upon reasonable request.
Author Contributions: Idea/concept, design, data
collection and/or processing, analysis and/or interpretation,
literature review, writing the article: B.Ş.; Analysis and/or
interpretation, critical review: G.G.; Literature review, critical
review: A.Ö.
Conflict of Interest: The authors declared no conflicts
of interest with respect to the authorship and/or publication
of this article.
Funding: The authors received no financial support for
the research and/or authorship of this article.