Clinical introduction A 52-year-old woman with shortness of breath and palpitations was referred to a cardiologist. A 24-hour Holter demonstrated high density (37%) of ventricular premature beats (VPBs) and long runs of non-sustained (eventually sustained) monomorphic ventricular tachycardia (VT) with the same morphology as several VPBs detected in a 12-lead ECG (figure 1A). A transthoracic echocardiogram was performed, and the patient’s evaluation was completed with a functional and gadolinium-enhanced cardiovascular MR (CMR) study (figure 1B,C) to assess structural heart disease. In a follow-up visit, an electrophysiological study (EPS) was performed to identify the origin of VPBs and VT (figure 1D).
Question What is the most likely cause of VPBs and VT?
Idiopathic VT in the absence of structural heart disease.
Bileaflet mitral valve prolapse (MVP).
Left ventricular non-compaction cardiomyopathy.
- ventricular tachycardia
- mitral regurgitation
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CMR imaging confirmed a bileaflet MVP with severe mitral regurgitation, mild left ventricular dilatation and dysfunction (figure 1B and online supplementary videos), and delayed enhancement involving the PMs (figure 1C). The patient underwent surgical mitral valve repair1 with a dramatic reduction in VPBs (37% preoperatively to 5% postoperatively). EPS was performed since symptomatic occasional palpitations were still present, demonstrating the origin of VPBs and VT at the anterior papillary muscle (PM) (asterisk; figure 1D).
PMs have been described as potential sources of idiopathic VT in the absence of structural heart disease2; however, this CMR confirmed MVP. Left ventricular dilatation is secondary to valvular heart disease, and thus, option C is incorrect. This patient does not meet the CMR criteria for left ventricular non-compaction cardiomyopathy,3 since prominent left ventricular trabeculae or a thin compacted layer is not present (figure 1B). The presence of delayed enhancement at both PMs (figure 1C) is not suggestive of ischaemic cardiomyopathy which typically appears with a subendocardial/transmural pattern in a coronary artery distribution. As demonstrated by Basso et al,4 5 some MVP cases are associated with life-threatening ventricular arrhythmias and sudden cardiac death, and the main structural hallmark consists of PMs fibrosis, suggesting myocardial stretch by the prolapsing leaflets and elongated chordae.
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LF-F and JS contributed equally.
Contributors Conception and design of study, acquisition of data, analysis and/or interpretation of data, approval of the version of the manuscript to be published: AF, LF-F, JS. Drafting the manuscript: AF, LF-F. Revising the manuscript critically for important intellectual content: LF-F, JS.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.