More than one third of patients will have chest pain associated with SVT causing providers to order troponins and other cardiac enzymes. Elevated troponins are not pathognomonic for CAD/ACS and could represent other etiologies such as sepsis, subarachnoid hemorrhage, and pulmonary embolism. Also, subsequent coronary angiography is not necessary for risk stratification in all cases. SVT causes a rapid heart rate, which is well documented as a cause for modest troponin elevation secondary to cardiac stretch, poor diastolic perfusion, and/or coronary artery vasospasm.
Do elevated troponins during SVT predict the presence of CAD?
- 12 – 48% of patients have elevated troponins after SVT 1,2
- Having a known history of CAD is more likely to lead to troponin elevation than not having a history of CAD (62% vs 43%)2
- There is no difference in the diagnosis of CAD compared to patients with negative troponins2
- And if that is not enough, here are 6 studies looking at patients with SVT followed by cardiac angiography.
|Author and Date||Study Type||Key Results (Angiography)|
|Kanjwal et al (2008)||Case Series (7 patients)||All with NORMAL coronary arteries|
|Miranda et al (2006)||Case Study||NORMAL coronary arteries|
|Yeo et al (2006)||Case series (3 patients)||All with NORMAL coronary arteries|
|Redfearn et al (2005)||Retrospective Cohort (3 patients)||All with NORMAL coronary arteries|
|Zellweger et al (2003)||Case Series (4 patients)||2 patients with NORMAL coronary arteries on angiography and 2 patients with normal myocardial perfusion scans|
|Bakshi et al (2002)||Prospective Cohort (3 patients)||All with NORMAL coronary arteries|
|Table modified from Carley S et al Best BETs 2005|
- Major Limitations:
- Few patients (21 patients total)
- Average age of patients between 40 – 45 (Younger patient population)
- Fewer ACS risk factors in these patients (Less likely to have CAD/ACS)
- Conclusion: Elevated troponins in younger patients with minimal risk factors for CAD/ACS in the setting of SVT do NOT predict CAD
Does an elevated troponin with SVT have any clinical prognostic significance? 3
In general, compared to the prior studies, patients in this study were older and had more comorbidities. The authors defined clinically significant outcomes as death, MI, or rehospitalization for a cardiac reason during a 1 year follow up after the SVT event. Several conclusions were made which included:
- Patients with more comorbidities (risk factors for ACS) are more likely to have elevated troponins with SVT
- In comparing elevated versus non-elevated troponin I levels post-SVT, the incidence of adverse outcomes was:
- Cardiac rehospitalization: 37.9% versus 6.1%
- Myocardial infarction: 6.9% versus 0% (Not Statistically Significant)
- Death: 20.7% versus 10.2% (Not Statistically Significant)
- Major Limitations:
- Retrospective Review
- 70% of patients did not have stress test or angiography for follow up
- Unclear if other etiologies such as pulmonary embolism, sepsis, or subarachnoid hemorrhage were cause of elevated troponins
- Conclusion: Patients with elevated troponins after SVT have INCREASED cardiac rehospitalization over the next year
Clinical Bottom Line:
A prospective study needs to be performed to determine the predictive value of elevated troponins in patients with SVT. A more appropriate approach based on the evidence should be:
- Low risk, prior SVT, feels good after conversion, then NO CARDIAC ENZYMES and outpatient f/u
- Intermediate risk, then DO get CARDIAC ENZYMES; If neg, outpatient follow up but if positive consider admission.
- High risk, older age, or known history of ACS, then DO CARDIAC ENZYMES and admit.