Case #18 — ST-Segment Elevation Soon after Coronary Artery Bypass Grafting

by Sanket Borgaonkar, MD, and Yochai Birnbaum, MD, FACC

A 59-year-old woman with hypertension, hyperlipidemia, and gastroesophageal reflux reported exertional angina that resolved with rest and nitroglycerin. Nuclear stress test results revealed a small, reversible inferior-wall defect and a left ventricular ejection fraction (LVEF) of 0.67. A coronary angiogram showed diffuse 3-vessel disease. The patient underwent elective 4-vessel coronary artery bypass grafting (CABG) with no complications and was extubated the next day. On postoperative day 2, a routine electrocardiogram (ECG) showed an rSr′ pattern in leads V₁ and V₂, and ST-segment elevation (STE) in leads V₂ through V₄ (Fig. 1).

Fig. 1

The patient reported no chest pain or dyspnea and had no murmurs, gallops, or rubs. A bedside echocardiogram showed preserved LVEF and no wall-motion abnormalities. Her initial troponin I level of 29.74 ng/mL decreased to 19.05 ng/mL 12 hours later.

The ECG shows which of the following?

A) Brugada phenocopy

B) Brugada type 2 pattern

C) Pericarditis

D) Acute anterior STE myocardial infarction (STEMI)

Answer

C) Pericarditis

The ECG shows concave STE in leads V₂ through V₄, and mild reciprocal ST-segment depression and PR elevation in lead aVR (Fig. 2), probably signifying postsurgical pericarditis.

Fig. 2

Brugada ECG patterns are classified as type 1 (a coved STE pattern >2 mm in leads V₁ through V₃ followed by a negative T wave) and type 2 (a saddleback STE pattern >2 mm).¹ Either pattern can be seen in patients with Brugada phenocopy, a phenomenon in which a true congenital Brugada syndrome is not present. The diagnostic criteria for Brugada phenocopy include the following^2,3: a type 1 or 2 Brugada pattern and a medical condition to explain it, resolution of that pattern when the underlying condition resolves, no symptoms (such as syncope), no family history suggesting Brugada syndrome, and negative provocative testing with a sodium-channel blocker.

Although our patient had saddleback STEs in lead V₂, her clinical presentation was more consistent with pericarditis. In addition, rSr′ patterns in Brugada type 2 indicate different phenomena. Benign patterns, typically when the initial r wave is taller than r′, occur in athletes, pectus excavatum, or partial right bundle branch block, and after higher chest-lead placement of electrodes V₁ and V₂. In pathologic rSr′ patterns (as in right ventricular enlargement or arrhythmogenic dysplasia, Wolff-Parkinson-White syndrome, or hyperkalemia), r′ tends to be taller than r.⁴ Furthermore, the β angle (which the r′ wave makes with the ST segment) can be used to diagnose type 2 Brugada syndrome by measuring the duration of the base of the triangle of r′ at 5 mm from the high takeoff. A β angle >3.5 mm suggests type 2 Brugada syndrome,¹ and our patient’s pattern did not meet this criterion. 

Acute STEMI was excluded: the patient was hemodynamically stable without chest pain and had preserved LVEF, normal wall motion, and decreasing troponin I levels (their elevation was probably secondary to recent CABG). Before her discharge from the hospital, the ST changes in the anterior leads resolved (Fig. 3).

Fig. 3

References

1. Bayes de Luna A, Brugada J, Baranchuk A, Borggrefe M, Breithardt G, Goldwasser D, et al. Current electrocardiographic criteria for diagnosis of Brugada pattern: a consensus report [published erratum appears in J Electrocardiol 2013;46(1):76]. J Electrocardiol 2012;45(5): 433-42.
2. Perez-Riera AR, Barbosa-Barros R, Daminello-Raimundo R, de Abreu LC, Baranchuk A. Unusual ST-segment elevation in the anterolateral precordial leads: ischemia, Brugada phenocopy, Brugada syndrome, all, or none? Circulation 2017;136(20):1976-8.
3. Ferrando-Castagnetto F, Garibaldi-Remunan A, Vignolo G, Ricca-Mallada R, Baranchuk A. Brugada phenocopy as a dynamic electrocardiographic pattern during acute anterior myocardial infarction. Ann Noninvasive Electrocardiol 2016;21(4):425-8.
4. Baranchuk A, Enriquez A, Garcia-Niebla J, Bayes-Genis A, Villuendas R, Bayes de Luna A. Differential diagnosis of rSr′ pattern in leads V1-V2. Comprehensive review and proposed algorithm. Ann Noninvasive Electrocardiol 2015;20(1):7-17. 

https://doi.org/10.14503/THIJ-18-6783