Fatal ventricular arrhythmias in myocarditis: A review of current indications for defibrillator devices

Historically, patients with myocarditis were considered for implantable cardioverter defibrillator (ICD) utilization only in the chronic phase of the disease following the development of persistent cardiomyopathy refractory to medical therapy or occurrence of a major ventricular arrhythmic event. However, recent literature has indicated that ventricular arrhythmias are frequently reported even in the acute phase of the disease, challenging the long-standing perception that this disease process was largely reversible. Given this changing environment of information, the latest US and European guidelines were recently updated in 2022 to now consider ICD implantation during the acute phase which has significantly increased the number of individuals eligible for these devices. Additionally, several studies with small subgroups of patients have demonstrated a possible benefit of wearable cardioverter defibrillators (WCDs) in this patient demographic. Assuming that larger studies confirm their utility, it is possible that WCDs can assist in detection of ventricular arrhythmias and selection of high-risk candidates for ICD implantation, while providing temporary protection for a small percentage of patients before the development of a major arrhythmic event. This review ultimately serves as a comprehensive review of the most recent guidelines for defibrillator use in acute and chronic myocarditis. OPINION STATEMENT: The latest US and European guidelines support ICD use for myocarditis patients following the development of persistent cardiomyopathy refractory to medical therapy or occurrence of a major ventricular arrhythmic event. Previously, patients in the acute phase were excluded from ICD utilization even after experiencing malignant ventricular tachycardia or ventricular fibrillation due to the long-standing perception that this disease process was largely reversible. However, recent literature has indicated that ventricular arrhythmias are frequently reported even in the acute phase of the disease. Additionally, we found that the myocardial damage that is inflicted persists many years after the initial episode. Given this changing environment of information, guidelines were recently updated in 2022 to now consider ICD implantation during the acute phase which has significantly increased the number of individuals eligible for these devices. We support possible ICD utilization for secondary prevention during the acute phase of myocarditis given the elevated risk of arrhythmia recurrence and the fact that any ventricular arrhythmia can induce sudden cardiac death. Future prospective studies are needed to assess which patients may benefit most from early ICD implantation. WCDs have improved survival in patient populations at high-risk for sudden cardiac death who are not candidates for ICD implantation. After analyzing several recent studies with small subgroups of patients, WCDs appear to demonstrate similar efficacy for myocarditis patients as well. Assuming that larger studies confirm their utility, we believe that WCDs can assist in detection of ventricular arrhythmias and selection of high-risk candidates for ICD implantation. Furthermore, WCDs have the additional benefit of acting as primary prevention by providing temporary protection for a small percentage of myocarditis patients before they develop a major arrhythmic event.

Coronary Sinus Thrombosis in a Patient Without History of Endothelial Cardiac Injury

Coronary sinus thrombosis (CST) is a rare but life-threatening condition that involves clot formation within the vessel responsible for draining all of the venous blood from the myocardium itself. The coronary sinus is situated in the right atrium approximately half-way between the tricuspid value and the inferior vena cava. The coronary sinus is rarely cited in medical literature due to limited knowledge as well as rarity in clinical encounters. CST can be a rapidly progressive life-threatening emergency as the interruption of vascular drainage can result in pericardial effusions, tamponade and cardiogenic shock. A major clinical challenge in diagnosing and treating this condition is due to relative rarity as well as the non-specificity of presenting symptoms that are often associated with more commonly encountered cardiopulmonary diseases. CST is most commonly induced by endothelial damage, such as post intracardiac instrumentation with catheter guidewires, or any of the criteria outlined by Virchow’s triad. Our team described the finding of a thrombus 1.8 cm in diameter in a patient with underlying hepatobiliary cancer as well as underlying bacteremia from infected ascitic fluid. Though our patient remained hemodynamically stable without cardiopulmonary complications, we hope to spark a discussion within the medical community to increase awareness as well as to highlight the need for more research on this potentially life-threatening condition.

Ankle-Brachial Index Testing at the Time of Stress Testing in Patients Without Known Atherosclerosis

BACKGROUND

Individuals referred for stress testing to identify coronary artery disease may have nonobstructive atherosclerosis, which is not detected by stress tests. Identification of increased risk despite a negative stress test could inform prevention efforts. Abnormal ankle-brachial index (ABI) is associated with increased cardiovascular risk.

HYPOTHESIS

Routine ABI testing in the stress laboratory will identify unrecognized peripheral arterial disease in some patients.

METHODS

Participants referred for stress testing without known history of atherosclerotic disease underwent ABI testing (n = 451). Ankle-brachial index was assessed via simultaneous arm and leg pressure using standard measurement, automated blood-pressure cuffs at rest. Ankle-brachial index was measured after exercise in 296 patients and 30 healthy controls. Abnormal postexercise ABI was defined as a >20% drop in ABI or fall in ankle pressure by >30 mm Hg.

RESULTS

Overall, 2.0% of participants had resting ABI ≤0.90, 3.1% had ABI ≥1.40, and 5.5% had borderline ABI. No patient with abnormal or borderline ABI had an abnormal stress test. Participants who met peripheral arterial disease screening criteria (age ≥65 or 50-64 with diabetes or smoking) tended toward greater frequency of low ABI (2.9% vs 1.0%; P = 0.06) and were more likely to have borderline ABI (0.91 to 0.99; 7.8% vs 2.9%; P = 0.006). Postexercise ABI was abnormal in 29.4% of patients and 30.0% of controls (P not significant).

CONCLUSIONS

Ankle-brachial index screening at rest just before stress testing detected low ABI in 2.0% of participants, all of whom had negative stress tests.