番茄社区

"Medical Journeys" is a set of clinical resources reviewed by doctors, meant for physicians and other healthcare professionals as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.

This month: A noteworthy case study.

Why did a man in his mid-50s develop unexplained chest pain that awakened him from a sound sleep, leaving him short of breath and soaked with sweat? That's the question that faced Gan-Xin Yan, MD, PhD, of Lankenau Medical Center in Wynnewood, Pennsylvania, and colleagues.

As they reported in , when the man arrived at the emergency department, the team found him in a state of wide complex tachycardia.

The patient's history included electrocardiogram findings of nonspecific T-wave abnormalities. Clinicians administered a 150 mg bolus of intravenous amiodarone, but there was no improvement in his arrhythmia.

After conferring, Yan and colleagues determined that synchronized cardioversion was needed, and delivered a biphasic direct current shock of 100 J.

The patient's vital signs were stable, and lab tests showed his serum electrolyte levels were within normal range and C-reactive protein (CRP) was less than 6 mg/dL. High sensitivity troponin levels increased to a peak of 1,078 pg/mL.

An initial 12-lead ECG showed that the patient remained in sinus rhythm, with brief episodes of ventricular tachycardia evident on telemetry.

He underwent cardiac catheterization, which revealed patent coronary arteries. Results of cardiac MRI were notable, with evidence of right ventricle dilation and a moderate decrease in systolic function, the case authors said. Additionally, there was "transmural late gadolinium enhancement with akinesis and dyskinesis involving the right ventricular (RV) freewall and outflow tract extending to the left ventricular (LV) anterior, septal, and apical segments."

Yan and colleagues diagnosed the patient with cardiac sarcoidosis, and obtained an 18F-fluorodeoxyglucose (FDG) PET scan of the heart. Results included evidence of focal/multifocal FDG uptake in the myocardium as well as in the lung. The lymph nodes in the chest and abdomen also showed FDG uptake, which the team said was suggestive of active myocardial and systemic sarcoidosis.

Clinicians placed an implantable cardiac defibrillator to reduce the risk of sudden cardiac death. The patient was discharged from the hospital after receiving medications to manage his heart failure with reduced ejection fraction, as indicated in the .

The patient was started on prednisone, "with plans for a prolonged taper for active systemic and cardiac sarcoidosis," the case authors explained. After being released, the patient underwent genetic testing for arrhythmogenic right ventricular cardiomyopathy (ARVC), which showed no evidence of a pathogenic mutation.

Discussion

Yan and co-authors noted that several ECG features suggested that the patient had ARVC. Particularly notable, they said, was the finding of a "low-amplitude, positive deflection between the end of the QRS complex and the onset of the T wave." This deflection was greatest in the right precordial leads (V2 and V3), which was consistent with an epsilon wave. As well, the ECG showed "both premature ventricular contractions (PVCs) and non-sustained ventricular tachycardia with a left bundle branch block (LBBB) morphology and an inferior axis."

T-wave inversions were evident in leads V1-V4, which Yan and team said were notable in the setting of a complete right bundle branch block (cRBBB).

They found that the patient met the following diagnostic criteria for ARVC:

• ECG evidence of epsilon waves (a major criterion)

• T-wave inversions in V1-V4 in the presence of cRBBB

• Telemetry evidence of >500 PVCs /24 hours

• Non-sustained ventricular tachycardia with LBBB morphology

Major imaging criteria also indicated the diagnosis of ARVC, the authors said -- for example, there was evidence of RV regional akinesis and dyskinesis on cardiac MRI, RV end diastolic volume greater than 110 mL/m², and decreased systolic function with an ejection fraction of 40% or lower.

"Notably, there was also significant LV involvement with late gadolinium enhancement composing 38% of total LV myocardial mass," Van and colleagues said. They pointed to one multicenter that found concomitant LV involvement in 76% of hearts with autopsy-proven ARVC.

Although the patient met the diagnostic criteria for ARVC, the case nonetheless raised "considerable debate about the underlying pathology given the initial ECG with a 'normal' first beat, in which the absence of cRBBB was accompanied by disappearance of T-wave inversion in lead V1," the authors wrote.

They explained that while the T-wave inversion in the right precordial leads is the most common ECG abnormality seen in ARVC, in this case it may represent a secondary effect of cRBBB conduction delay.

The authors noted that despite being a key diagnostic criterion, the occurrence of epsilon waves in the right precordial leads is not necessarily characteristic of ARVC; rather, it is "an electrical marker of delayed activation of the right ventricular free wall and outflow tract." As such, it occurs in various heart conditions that affect the right ventricle, such as myocardial infarction, and sarcoidosis.

can also occur in the setting of myocarditis, although the undetectable levels of inflammatory markers such as erythrocyte sedimentation rate and CRP favored strongly against active myocarditis.

Regarding management decisions for this patient, Yan and co-authors noted that ECG imaging has limited ability to "definitively evaluate for major imaging features" that would help differentiate ARVC from cardiac sarcoidosis. Thus, the cardiac FDG PET scan represented the best diagnostic tool in this case.

Read previous installments in this series:

Part 1: Cardiomyopathy: What are the Signs, What are the Symptoms?

Part 2: Diagnosing Cardiomyopathy: History, Examination, and Testing

Part 3: Cardiomyopathy: Epidemiology, Etiology, and Pathophysiology

Part 4: Case Study: Cardiac Sarcoidosis in Man With Palpitations, Dyspnea

Part 5: Cardiomyopathy: Cascade Screening for Families

Part 6: Cardiomyopathy: Outside of the Office

Part 7: Deciding on Implantable Cardiac Devices for Cardiomyopathy