What is the clinical evidence from this study?

Study design: Observational. Population: Idiopathic intermittent left bundle branch block (ILBBB) (n=14). Primary outcome: Presence of memory-related negative T waves during normal conduction and homophasic T waves during LBBB.

What question did this study set out to answer?

This report aims to characterize a distinct electrocardiographic phenotype associated with cardiac memory in idiopathic ILBBB.

March 25, 2026Open Access

Homophasic idiopathic intermittent left bundle branch block and cardiac memory (OIL-CAME): reappraisal of a distinct electrocardiographic phenotype

Key Result

In 14 patients with idiopathic intermittent left bundle branch block, all exhibited a distinct electrocardiographic phenotype characterized by memory-related negative T waves during normal conduction and homophasic T waves during LBBB.

Key Points

This report aims to characterize a distinct electrocardiographic phenotype associated with cardiac memory in idiopathic ILBBB.
Retrospective analysis of 14 patients with idiopathic, rate-dependent ILBBB.
Assessment of T wave changes in leads V5–V6 and right precordial leads.
Evaluation of intraventricular conduction zone width in relation to repolarization abnormalities.
Memory-related negative T waves were consistently observed during normal conduction.
Concordant (homophasic) T waves were noted during LBBB.
Narrower conduction zones correlated with deeper negative T wave inversion during normal conduction.
Most patients progressed to permanent LBBB during follow-up without major arrhythmic events.

Study Design

Type

Observational (n=14)

Multicenter

Yes

Structured PICO

Population

Patients with idiopathic, rate-dependent intermittent left bundle branch block (ILBBB), absence of demonstrable structural heart disease, homophasic T waves in leads V5-V6 during LBBB, and pseudo-ischemic T wave inversion in the right precordial leads during normal conduction.

Outcome

Electrocardiographic phenotype characterization and clinical/electrocardiographic evolution during follow-up.

Describes a distinct electrocardiographic phenotype (OIL-CAME) in idiopathic intermittent LBBB characterized by memory-related T wave inversion mimicking ischemia, which typically progresses to permanent LBBB without major arrhythmic events.

Limitations

Inability to record the very first beats during the onset of LBBB to directly assess whether initial repolarization was discordant or concordant
Inability to observe the temporal evolution of T wave morphology during the development of cardiac memory
Retrospective design with a small sample size

Abstract

Aim: Cardiac memory is classically expressed as persistent T wave changes following restoration of normal ventricular activation. Its manifestations in idiopathic intermittent left bundle branch block (ILBBB) remain incompletely characterized. The aim of this report is to describe a distinct electrocardiographic phenotype potentially related to cardiac memory. Methods: We retrospectively analyzed a homogeneous series of 14 patients with idiopathic, rate-dependent ILBBB, absence of demonstrable structural heart disease, homophasic T waves in leads V5–V6 during left bundle branch block (LBBB), and pseudo-ischemic T wave inversion in the right precordial leads during phases of normal conduction. Results: In all patients, memory-related negative T waves were observed during normal conduction, while concordant (homophasic) T waves were consistently present during LBBB. A close relationship emerged between the width of the intraventricular conduction zone and the severity of repolarization abnormalities: narrower conduction zones were associated with deeper T wave inversion during normal conduction. During follow-up, most patients progressed to permanent LBBB, without documented major arrhythmic events. Conclusions: These findings describe a distinctive and reproducible electrocardiographic phenotype within idiopathic ILBBB, likely related to cardiac memory. This pattern, provisionally designated homophasic idiopathic intermittent left bundle branch block and cardiac memory (OIL-CAME), warrants further confirmation in larger prospective studies.

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