Key result
Single ventricular extrastimuli with variable coupling intervals from the left-right coronary cusp junction successfully reproduced multiform QRS morphologies identical to the patient's clinical VPCs.
Case Report (n=1)
This case demonstrates that a single focus VPC can exhibit multiform morphology due to varying fusion with intrinsic conduction, highlighting the importance of coupling interval-matched extrastimuli in identifying the origin.
May indicate single-focus multiform VPCs via fusion; case reports leave open whether variable coupling intervals are routinely needed for mapping.
INTRODUCTION: A 22-year-old male with no cardiovascular history presented with frequent symptomatic ventricular premature contractions (VPCs) with multiple QRS morphologies despite bisoprolol treatment. RESULTS: The coupling intervals progressively increased from VPC1 to VPC3, and VPC2 was the most frequent. The earliest activation site was identified at the left-right coronary cusp junction. Single ventricular extrastimuli with variable coupling intervals from this site successfully reproduced QRS morphologies identical to VPC1-3. CONCLUSION: This case illustrated how a single focus VPC could exhibit multiform morphology due to varying fusion with intrinsic conduction and the importance of coupling interval-matched extrastimuli in identifying the origin.
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Miwa et al. (2025) conducted a case report in Ventricular premature contractions with multiple QRS morphologies (n=1). Single ventricular extrastimuli with variable coupling intervals was evaluated on Reproduction of QRS morphologies identical to clinical VPCs. Single ventricular extrastimuli with variable coupling intervals from the left-right coronary cusp junction successfully reproduced multiform QRS morphologies identical to the patient's clinical VPCs.
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