From the Guidelines
Nonspecific intraventricular conduction delay (NIVCD) on an EKG is defined as a QRS duration greater than 110 ms in adults, without the characteristic patterns of right or left bundle branch blocks, as stated in the 2009 AHA/ACCF/HRS recommendations 1.
Definition and Criteria
The criteria for NIVCD include a QRS duration greater than 110 ms in adults, greater than 90 ms in children 8 to 16 years of age, and greater than 80 ms in children less than 8 years of age, as defined by the American Heart Association electrocardiography and arrhythmias committee 1.
Clinical Significance
NIVCD can result from various causes including coronary artery disease, cardiomyopathy, hypertension, electrolyte abnormalities, medication effects, or congenital heart disease.
- It is essential to identify and address the underlying cause of NIVCD.
- The finding may warrant further cardiac evaluation, including echocardiography or stress testing, especially if the patient has symptoms like chest pain, shortness of breath, or palpitations.
- NIVCD may sometimes progress to more severe conduction abnormalities over time, so periodic monitoring with follow-up EKGs is often recommended.
Diagnosis and Evaluation
The 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay provides a comprehensive overview of conduction tissue disease, including NIVCD 1.
- The guideline defines NIVCD as a QRS duration greater than 110 ms, where morphology criteria for RBBB or LBBB are not present.
- The international recommendations for electrocardiographic interpretation in athletes also discuss NIVCD, recommending further evaluation for marked nonspecific IVCD ≥140 ms in athletes, regardless of QRS morphology 1.
Management and Treatment
While NIVCD itself doesn't typically require specific treatment, it's crucial to address the underlying cause and monitor the patient's condition to prevent progression to more severe conduction abnormalities.
- The management of NIVCD should focus on treating the underlying condition, such as coronary artery disease, cardiomyopathy, or hypertension.
- Periodic monitoring with follow-up EKGs is essential to detect any changes in the conduction system and prevent complications.
From the Research
Definition and Pathophysiology
- Nonspecific intraventricular conduction delay (NICD) is a condition characterized by a widened QRS complex on the electrocardiogram (ECG) that is neither a left bundle branch block (LBBB) nor a right bundle branch block (RBBB) 2.
- The pathophysiology of NICD is complex and varied, reflecting intramyocardial conduction delay, and is often associated with cardiomyopathy (e.g., ischemic or hypertensive) 2.
- Conduction pathways in NICD can be either healthy or affected, and the condition is less studied than RBBB or LBBB 2.
Association with Ischemic Heart Disease
- Ischemic heart disease is a dynamic process of atherosclerosis of the coronary arteries or functional alterations of coronary circulation, which can be modified by lifestyle, pharmacological therapies, and revascularization 3.
- NICD is often associated with ischemic heart disease, particularly in patients with cardiomyopathy 2.
- The pathophysiology of ischemic heart disease is multifaceted and not always determined by atherosclerotic plaque complication, involving microvascular dysfunction and ion channel imbalance 4, 5.
Diagnostic and Therapeutic Implications
- Cardiac resynchronization therapy (CRT) is an electrical treatment for heart failure with reduced ejection fraction and wide QRS, aiming to correct electrical dyssynchrony 2.
- The effectiveness of CRT in patients with NICD is contradictory, and prospective studies are lacking 2.
- Noninvasive imaging modalities, such as coronary CT angiography, cardiac MR, and PET myocardial perfusion imaging, can help assess the degree of anatomic stenosis and detect myocardial infarction 6.