Discussion
The present study demonstrated that among STEMI patient population, the
presence of moderate to severe TR was associated with significantly
lower survival rate compared to patients with mild/no TR. TR was
associated with excess mortality even when adjusted for demographic,
clinical and other echocardiography parameters.
To our knowledge, this is the first report to date suggesting a possible
prognostic implication of TR in STEMI patients.
TR is a common echocardiographic finding 19, but has
been disregarded due to the credence that it is a clinically
insignificant condition. The clinical impact and outcome of TR are
difficult to assess, given its heterogeneity and the association with
numerous comorbidities. Hence, management guidelines of TR patients
remain ambiguous due to conflicting studies results9,20,21. Pivotal studies suggested that untreated TR
is associated with excess mortality and cardiac events7,21. TR had been associated in previous studies with
additional cardiovascular outcomes. It has been shown that TR is a
common finding in patients with left-sided valvular disease. Significant
TR in this circumstance is considered as a late-stage marker and is
associated with poor outcome and worse prognosis21–23. Therefore, patients undergoing left valve
surgery with severe functional TR (FTR) have a class I indication for
concomitant tricuspid valve surgery 24. In patients
undergoing transcatheter aortic valve replacement (TAVR) the impact of
preoperative significant TR was associated with almost a 2-fold increase
in 2-year mortality 23.
TR is also common among patients with chronic heart failure (CHF), due
to the pathophysiology of CHF resulting in right ventricular dilatation,
and the development of FTR which, consequently, generating further right
ventricular dilatation and worsening of TR 25. Studies
indicate a strong impact of TR on the clinical outcome in CHF patients,
where TR was significantly related to mortality 26.
Recent studies had demonstrated that moderate-severe TR is associated
with poor outcome, even in the absence of left ventricular dysfunction
or pulmonary hypertension 3,7,9, implying that
tricuspid valve repair or replacement may lead to a survival benefit.
However, to date, TR patients are rarely referred for isolated surgical
tricuspid valve repair, and these are mostly performed during other
planned cardiac surgery 5,27,28. In the era where
percutaneous repair procedures are on the rise, more research on
percutaneous approaches for TR is needed 28.
Limited data exist on the prevalence and prognostic value of significant
TR in STEMI patients undergoing PCI. In the setting of acute occlusion
of the right coronary artery leading to inferior MI, RV involvement, and
concomitant severe TR, tricuspid papillary muscle rupture (PMR) had been
reported as a rare complication 29,30.
The present study provides, for the first time, evidence that moderate
to severe TR can serve as a possible prognostic marker among STEMI
patients. We found that among STEMI patients undergoing primary PCI,
with no previous TR, the prevalence for developing moderate to severe TR
was 2.7%. These patients suffered more in-hospital complications and
worse long-term outcomes. These results imply that in patients
developing moderate to severe TR, additional follow up after PCI is
needed. Once released from hospital these patients should be followed by
a cardiologist, undergo an additional echocardiographic exam to track
progression of TR severity and possibly electrocardiogram exam due to a
high prevalence of arrythmias. An
extra emphasis should be placed on balancing of cardiovascular risk
factors for these patients.
Though the reason for higher mortality among STEMI patients with
significant TR is yet unclear, we postulate that the presence of TR
after STEMI could be a marker of decreased RV function and
contractility. It has been shown that the presence of severe TR can be
attributed to RV akinesis in the settings of inferior MI or to ischemic
impairment of the tricuspid valve 29. Moreover,
increasing severity of TR is allied with RV dilation, dysfunction and
elevated right atrial pressure, therefore leading to a worse outcomes25. In addition, the association between enlarged RV
and increased mortality was demonstrated in previous studies31,32, elucidating that RV function after STEMI has
important prognostic implications. Nevertheless, from our understanding
the RV function influence on outcomes only partly explains the
association between significant TR among STEMI patients and mortality,
therefore, additional research is needed in order to illuminate the
matter.
We acknowledge several important limitations of our study. This was a
single-center retrospective and non-randomized observational study;
because of its retrospective nature, the study was subjected to
selection bias, and therefore the results point toward association, and
not cause and effect.
The study included only patients with first MI who were undergoing
primary PCI and with no previous TR. Therefore, the results cannot be
generalized to all STEMI patients with TR. The group with moderate to
severe TR was small, patients were significantly older, female and with
CKD. We attempted to adjust for confounding factors using the
multivariate Cox hazard model, however, most of the study population
were men, hence the data may not be applicable to female patients.
Finally, data were collected retrospectively from echocardiographic
reports who were recorded and analyzed by different sonographers. An
echocardiographic exam is highly operator dependent which may be
subjective, even though it was determined by echocardiography experts.