Washington University Emergency Medicine Journal Club- October 2023
You are working a shift in EM1 one afternoon when you encounter Mr. Steven Von
Trachtenberg, a pleasant 45-year old male who presents with palpitations that
began one hour prior to arrival. He notes a sense of his heart racing and has
shortness of breath with no chest pain. He reports drinking four Rockstar energy
drinks that morning after sleeping poorly last night and wonders if that could be
why his heart is trying to beat out of his chest.
An ECG reveals that your patient is in SVT with a rate of 190 beats per minute. His
blood pressure is 140/90 and he appears to be in no distress. The nurse places an IV
and draws labs and you administer 6 mg of IV adenosine which successfully converts
the patient into sinus rhythm with a rate of 105. Your patient feels much improved.
You leave the room and start to order labs, including electrolytes, thyroid studies,
and a CBC. As you go to enter the order for a troponin series, you wonder if it’s really
necessary to routinely check cardiac enzymes in patients with simple SVT. If they’re
elevated, is it simply a result of the rapid heart rate, or is it predictive of underlying
coronary artery disease? You wonder if any risk factors (chest pain, age, known
coronary artery disease) would increase their utility. Unsure what to do, you go
online and begin searching for answers…
Population: Adults patients presenting to the ED for an episode of supraventricular
tachycardia (i.e. AV re-entrant tachycardia or AV nodal re-entrant tachycardia)
Intervention: Cardiac troponin testing
Comparison: No cardiac troponin testing
Outcome: Presence of significant coronary artery disease, recurrence of SVT, death,
need for revascularization
PubMed was searched using the terms “(SVT OR “supraventricular tachycardia”)
AND troponin” (https://tinyurl.com/mk2bbezd). This resulted in 89 citations, from
which 4 relevant articles were chosen. The Cochrane Database of Systematic
Reviews was searched using the terms “SVT or supraventricular tachycardia” but did
not reveal any relevant systematic reviews.
Article 1: Gabrielli M, Cucurachi R, Lamendola P, Candelli M, Pignataro G, Del Bono
G, Franceschi F. Troponin Testing in Adult Patients Presenting to the Emergency
Department for Paroxysmal Supraventricular Tachycardia: A Review. Cardiol Rev.
2023 Sep-Oct 01;31(5):265-269. Answer Key.
Article 2: Yen CC, Chen SY, Chaou CH, Wang CK, Yeh HT, Ng CJ. Prognostic Value of
Cardiac Troponin and Risk Assessment in Pediatric Supraventricular Tachycardia. J
Clin Med. 2021 Aug 17;10(16):3638. Answer Key.
Article 3: Fernando H, Adams N, Mitra B. Investigations for the assessment of adult
patients presenting to the emergency department with supraventricular
tachycardia. World J Emerg Med. 2020;11(1):54-59. Answer Key.
Article 4: Chen JL, Hsiao CH, Yen CC. Prognostic value of cardiac troponin in elderly
patients with paroxysmal supraventricular tachycardia: A multicenter study. Am J
Emerg Med. 2023 Jul;69:167-172. Answer Key.
While cardiac troponin values are frequently tested in patients presenting to the ED
with supraventricular tachycardia (SVT), the clinical utility of this practice has been
called into question. Previous research has demonstrated no association between
elevated cardiac enzymes and diagnosis of coronary artery disease (CAD) in patients
presenting to the ED with SVT (Bukkapatnam 2010). We sought to more broadly
evaluate the correlation between elevated troponin and significant CAD in this
patient population, as well as assess the potential predictive value of troponin for
cardiac adverse events in various patient populations.
While it seems intuitive that pediatric patients with SVT would be at low risk of
significant adverse cardiac events, a retrospective, multicenter, observational study
conducted at 5 hospitals in Taiwan was undertaken to evaluate this hypothesis (Yen
2021). Among 112 pediatric patients with SVT who underwent troponin testing,
values were positive in 25.9%. There were no major adverse cardiac events (MACE)
in those with a positive troponin, and one MACE among those with negative values.
SVT recurred within 30 days in 6 cases in the troponin positive group (20.7%) and 6
cases in the troponin negative group (7.2%, relative risk [RR] 2.86, 95% CI 1.00 to
8.18). ICU admission rates were higher in troponin positive patients and there was a
trend toward increased hospital length of stay (48.3 hours vs. 28.4 hours).
At the other end of the age spectrum are elderly patients. Another retrospective,
multicenter, observational study conducted at 4 hospitals in Taiwan enrolled only
patients aged 65 or older presenting with SVT who had troponin testing (Chen
2023). Of 124 patients enrolled, 31.5% had a positive cardiac troponin (only slightly
higher than the proportion in pediatric patients). Patients with a positive troponin
were more likely to require hospital admission, require ICU admission, and have a
cardiology consult. There was no significant difference in the 5-year risk of a major
adverse cardiac event between those with positive and negative troponin (RR 0.97,
95% CI 0.32 to 2.95).
A single-center retrospective cohort study conducted in Melbourne, Australia sought
to evaluate the effect of testing in general on a more heterogenous group of all adults
presenting to the ED with SVT (Fernando 2020). The enrolled 226 patients, of whom
nearly all (94.2%) underwent at least one adjunct investigation and just over half
(51.3%) underwent troponin testing. While a change in management was attributed
to an abnormal investigation result in 62 cases (27.4%, 95% CI 21.7% to 33.7%),
most of the changes actually occurred in patients with normal testing: 28 patients
received potassium supplementation, of whom 17 had levels within the normal
reference range, and 31 patients received magnesium supplementation, of whom 26
had levels within the normal reference range. Of 116 patients who underwent
troponin testing, 35 (30.2%) were positive, none of whom were found to have acute
coronary syndrome despite two undergoing coronary angiography and four
undergoing myocardial perfusion scans. There were two patient with initially
negative troponin (but subsequent positive values) who were diagnosed with
NSTEMI; both of these had chest pain and shortness of breath and only one required
Finally, a narrative review seeking to provide a comprehensive synthesis of
literature on the diagnostic and prognostic value of cardiac troponin in patients
presenting to the ED for SVT was published in 2023 (Gabrielli 2023). The authors
identified 11 relevant articles for review, only one of which was prospective in
nature. They concluded that CAD was overall rare in patients presenting with
paroxysmal SVT and that cardiovascular risk factors, rather than troponin results,
should guide decisions to pursue further testing for ischemic heart disease. Cardiac
troponin, according to the authors, was more useful in assessing long-term
prognosis among those with an elevated cardiovascular risk.
These conclusions are similar to those drawn from the studies reviewed herein.
When checked, troponin will be elevated in a substantial proportion patients
presenting to the ED with SVT (including pediatric patients). When elevated,
troponin was not associated with a higher risk of coronary artery disease or major
adverse cardiovascular events when compared to those with normal troponin
values. It is more likely that prolonged cardiac strain from an elevated heart rate,
rather than underlying coronary occlusion, is responsible for these elevated values;
similar results have been seen in studies of troponin values in asymptomatic
runners following a marathon (Shave 2002, Eijsvogels 2015, Gresslien 2016). The
decision to check lab work in general, and cardiac troponins specifically, in patients
presenting with SVT should not be routine, but instead should be based on the
clinicians level of concern and risk factors for clinically significant abnormalities.
Patients without significant risk factors for CAD and without concomitant
concerning symptoms may benefit from not having cardiac enzymes testing.