A patient in their 70s with a long history of smoking presented to the emergency department with 2 months of intermittent chest pain worsening followed by a syncope episode. The symptoms persisted for a few minutes and resolved spontaneously. The symptoms recurred and became increasingly frequent.

On arrival, the patient had normal vital signs, physical examination results, and troponin I, serum electrolyte, and blood glucose levels. Chest and cranial computed tomographic findings confirmed no space-occupying lesions. An asymptomatic electrocardiogram (ECG) showed a sinus rhythm of 59 beats per minute with 1-mm to 2-mm horizontal ST-segment depressions and T-wave inversions in the inferior (II, III, and aVF) and inferolateral (V₄ through V₆) leads. Echocardiogram findings revealed a mildly thickened ventricular septum with preserved left ventricular systolic function.

Question: What is the cause of the symptoms, and what is the most likely diagnosis and management strategy?

The presenting ECG pattern on admission raised suspicion of angina due to the visible ST-segment depressions, implying that the ischemic region was associated with the stenosis of the artery suspected to be affected. The patient was transferred for selective coronary angiography. On day 3 after admission, the patient re-experienced several episodes of spontaneous chest pain accompanied by syncope in the early morning, with each episode lasting for less than 15 minutes. Twelve-lead Holter monitoring during syncope detected a bradyarrhythmia without ventricular tachyarrhythmia. A dramatic ST-segment elevation pattern related to chest pain was observed, accompanied by a high-degree atrioventricular block associated with syncope (Figure, A). There was progressive evolution of the typical pattern, causing advanced atrioventricular blocks in lead II (Figure, B). No pathologic Q waves were observed after the episode. The cause of spontaneous symptoms with transient ECG changes suggested variant angina (VA). Following intravenous long-acting nitrate injection, a temporary cardiac pacemaker was implanted. Urgent angiography revealed 50% vasospastic stenosis in the proximal segment of the right coronary artery (RCA) and 90% focal stenosis in the midportion of the left circumflex artery (LCX). Subsequently, the patient was administered intravenous long-acting nitrate and oral diltiazem. On day 5 postadmission, repetitive angiography demonstrated a normal luminal diameter of the proximal RCA and persistent stenosis in the middle LCX. A drug-eluting stent was placed in the LCX. The patient was free of symptoms and discharged on day 8 of hospitalization with oral medications. ECG re-examination showed recovery of abnormal ST-T changes in multiple leads. Six months later, 12-lead Holter monitoring recorded normal ST segments with a sinus rhythm.

The striking finding pointing to the cause of symptoms is multivessel spasm with obstructive organic stenosis resulting in severe myocardial ischemia, which is characterized by a lambdalike ST-segment elevation implying the site and severity of ischemia, followed by high-degree atrioventricular block on ECG. Previous angiographic demonstrations confirmed that coronary spasm was the cause of spontaneous chest pain associated with transient ST-segment elevation in most patients with VA, even with obstructive organic lesions. VA is considered a type of vasospastic angina.¹ Vasospastic angina is defined as a 90% constriction of the coronary arteries on angiography, accompanied by spontaneous ischemic symptoms and/or transient ST-T changes on ECG.² Spontaneous chest pain with transient ST elevation more than 1 mm in at least 2 contiguous ECG leads was consistent with VA in this patient.

The inferior leads (II, III, and aVF) showed a giant R wave (amplitude of 1 mV or greater) that merged with the remarkable ST-segment elevation, forming the lambda wave pattern.^3,4 This was first described in a young man who died while asleep with giant triangular waveforms in leads II, III, and aVF.³ The sudden death resulted from an episode of ventricular fibrillation, which was recorded completely by Holter monitoring. Gussak et al⁴ called it a new predictor for sudden cardiac death. This pattern is associated with increased risk of impending malignant arrhythmias, including ventricular tachycardia, ventricular fibrillation, and high-degree atrioventricular block.^5,6

The lambdalike ST-segment elevation, corresponding to the distribution of the major coronary artery in inferior leads (II, III, and aVF), was related to complete spastic occlusion of the LCX or RCA. Experimental and clinical studies have confirmed that atherosclerotic plaque can induce vasospasm; conversely, spasm itself can initiate or aggravate atherosclerosis.⁷ Initially, spasm occurs in the LCX based on severe organic stenosis of the middle segment. In this patient, the higher ST-segment elevation in lead II compared with lead III and ST-segment elevation in leads I, aVL, and V₄ through V₆ with ST-segment depression in leads aVR and V₁ through V₃ collectively suggest total occlusion of the LCX (Figure, A). Subsequently, spasms occurred in the RCA. A contrary ECG pattern, especially higher ST-segment elevation in lead III than in lead II and in lead V₁ than in lead V₃, with greater ST-segment depression in lead aVL than in lead I, suggests occlusion of the proximal RCA (Figure, C). Repetitive angiography also demonstrated spasm in the RCA. If blood supply to the atrioventricular node is impaired by coronary spasm with significant organic stenosis, a high-degree atrioventricular block can easily occur in patients with syncope.

Smoking cessation is indispensable in VA treatment. Appropriate doses of nondihydropyridine calcium antagonists are effective and safe for suppressing coronary spasm attacks triggering high-degree atrioventricular blocks. Nevertheless, to our knowledge, nonpharmacological therapies have not been demonstrated to prevent the recurrence of involved fatal arrhythmias or sudden death. Consequently, long-term sufficient and reliable medical treatment is required to prevent recurrence of coronary spasm and improve poor prognosis in VA with severe organic stenosis.²

The lambda waveform, as an ominous ECG sign of lethal arrhythmias, can indicate coronary spasm in VA with severe organic stenosis. Physicians must immediately recognize this pattern and administer therapy to relieve the relevant symptoms.

• The lambda wave pattern is a high-risk indicator for life-threatening arrhythmias in ECG.

• Twelve-lead Holter monitoring can record dynamic changes in the lambda wave pattern and avoid the delay or oversight of diagnosis in patients with unexplained syncope.

• The lambda wave pattern is a transient and maximum state of ST-segment elevation, suggesting the severity of ischemia due to coronary spasm with severe organic stenosis. It warrants urgent therapy to relieve relevant symptoms, mainly removal of predisposing causes, revascularization, and medication.

• Appropriate doses of nondihydropyridine calcium antagonists are effective and safe in managing coronary spasm鈥搃nduced angina and high-degree atrioventricular block.

• Comprehensive assessment is essential to understand risk factors for prognosis in VA with severe organic stenosis.

Corresponding Author: Guangqiang Wang, MS, Department of Cardiology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, No. 20 Yuhuangding East Rd, Yantai 264000, China (wgq198632@126.com).

Published Online: June 24, 2024. doi:10.1001/jamainternmed.2024.1005

Conflict of Interest Disclosures: None reported.