Clinical Research
Hypertrophic Cardiomyopathy
Occurrence and Frequency of Arrhythmias in Hypertrophic Cardiomyopathy in Relation to Delayed Enhancement on Cardiovascular Magnetic Resonance

https://doi.org/10.1016/j.jacc.2007.11.071Get rights and content
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Objectives

Our aim was to determine whether myocardial fibrosis, detected by cardiovascular magnetic resonance (CMR), represents an arrhythmogenic substrate in hypertrophic cardiomyopathy (HCM).

Background

Myocardial fibrosis is identified frequently in HCM; however, the clinical significance of this finding is uncertain.

Methods

We studied prevalence and frequency of tachyarrhythmias on 24-h ambulatory Holter electrocardiogram (ECG) with regard to delayed enhancement (DE) on contrast-enhanced CMR in 177 HCM patients (age 41 ± 16 yrs; 95% asymptomatic or mildly symptomatic).

Results

Premature ventricular contractions (PVCs), couplets, and nonsustained ventricular tachycardia (NSVT) were more common in patients with DE than those without DE (PVCs: 89% vs. 72%; couplets: 40% vs. 17%; NSVT: 28% vs. 4%; p < 0.0001 to 0.007). Patients with DE also had greater numbers of PVCs (202 ± 655 vs. 116 ± 435), couplets (1.9 ± 5 vs. 1.2 ± 10), and NSVT runs (0.4 ± 0.8 vs. 0.06 ± 0.4) than non-DE patients (all p < 0.0001); DE was an independent predictor of NSVT (relative risk 7.3, 95% confidence interval 2.6 to 20.4; p < 0.0001). However, extent (%) of DE was similar in patients with and without PVCs (8.2% vs. 9.1%; p = 0.93), couplets (8.5% vs. 8.4%; p = 0.99), or NSVT (8.3% vs. 8.5%; p = 0.35).

Conclusions

In this large HCM cohort with no or only mild symptoms, myocardial fibrosis detected by CMR was associated with greater likelihood and increased frequency of ventricular tachyarrhythmias (including NSVT) on ambulatory Holter ECG. Therefore, contrast-enhanced CMR identifies HCM patients with increased susceptibility to ventricular tachyarrhythmias.

Abbreviations and Acronyms

CMR
cardiovascular magnetic resonance
DE
delayed enhancement
ECG
electrocardiogram
HCM
hypertrophic cardiomyopathy
ICD
implantable cardioverter-defibrillator
LV
left ventricular/ventricle
NSVT
nonsustained ventricular tachycardia
PVC
premature ventricular contraction
ROC
receiver-operating characteristic
SVT
supraventricular tachycardia

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Dr. Adabag is supported in part by the Veterans Administration Clinical Science Research and Development Service (grant no. 04S-CRCOE 001), Washington, DC.