High-resolution three-dimensional late gadolinium-enhanced cardiac magnetic resonance imaging to identify the underlying substrate of ventricular arrhythmia

Abstract

Aims: Cardiac magnetic resonance (CMR) is recommended as a second-line method to diagnose ventricular arrhythmia (VA) substrate. We assessed the diagnostic yield of CMR including high-resolution late gadolinium-enhanced (LGE) imaging.

Methods and results: Consecutive patients with sustained ventricular tachycardia (VT), non-sustained VT (NSVT), or ventricular fibrillation/aborted sudden death (VF/SCD) underwent a non-CMR diagnostic workup according to current guidelines, and CMR including LGE imaging with both a conventional breath-held and a free-breathing method enabling higher spatial resolution (HR-LGE). The diagnostic yield of CMR was compared with the non-CMR workup, including the incremental value of HR-LGE. A total of 157 patients were enrolled [age 54 ± 17 years; 75% males; 88 (56%) sustained VT, 52 (33%) NSVT, 17 (11%) VF/SCD]. Of these, 112 (71%) patients had no history of structural heart disease (SHD). All patients underwent electrocardiography and echocardiography, 72% coronary angiography, and 51% exercise testing. Pre-CMR diagnoses were 84 (54%) no SHD, 39 (25%) ischaemic cardiomyopathy (ICM), 11 (7%) non-ischaemic cardiomyopathy (NICM), 3 (2%) arrhythmogenic right ventricular cardiomyopathy (ARVC), 2 (1%) hypertrophic cardiomyopathy (HCM), and 18 (11%) other. CMR modified these diagnoses in 48 patients (31% of all and 43% of those with no SHD history). New diagnoses were 9 ICM, 28 NICM, 8 ARVC, 1 HCM, and 2 other. CMR modified therapy in 19 (12%) patients. In patients with no SHD after non-CMR tests, SHD was found in 32 of 84 (38%) patients. Eighteen of these patients showed positive HR-LGE and negative conventional LGE. Thus, HR-LGE significantly increased the CMR detection of SHD (17-38%, P < 0.001).

Conclusion: CMR including HR-LGE imaging has high diagnostic value in patients with VAs. This has major prognostic and therapeutic implications, particularly in patients with negative pre-CMR workup.

Figure 1

Diagnostic categories before and after CMR in 157 consecutive patients presenting with a first episode of ventricular arrhythmia (52 NSVT, 88 sustained VT, and 17 VF/SCD).

Figure 2

Diagnostic yield of pre-CMR and CMR tests in the 112 patients with no prior history of structural heart disease.

Figure 3

Examples of typical diagnostic changes introduced by CMR. Cine images at end diastole (left column), end systole (middle column), and LGE images (right column) are provided. (A) Image of a 44-year-old man with monomorphic sustained VT of RBBB morphology. TTE, coronary angiography, and cine MRI were negative. LGE showed multifocal substrate on LV and RV free walls and within the septum (arrows), categorized as NICM. The diagnosis of cardiac sarcoid was retained after transbronchial biopsy. (B) Image of a 34-year-old man with NSVT of unkown morphology, negative TTE, and non-specific T wave changes on ECG. Cine and LGE MR showed apical hypertrophy with midwall fibrosis (arrows), consistent with an apical form of HCM. (C) Image of a 58-year-old women with sustained VT of RBBB morphology. TTE, coronary angiography and cine MR were negative. LGE showed subendocardial scar on mid anterior LV, consistent with ICM. The patient had a history of severe asthma, and CMR results were instrumental in fulfilling the diagnostic criteria for eosinophilic granulomatosis with polyangiitis. (D) Image of a 41-year-old man with pre-CMR borderline ARVC diagnosis based on polymorphic sustained VT at exercise tesing, late potentials on SAECG, and inverted T waves in ECG leads V1–V2. Cine MR results fulfilled the criteria for definite ARVC by showing RV dilatation, EF impairment, and RVOT dyskinesia. LGE showed diffuse fibrosis on RV free wall, and focal midwall fibrosis on LV free wall (arrows). (E) Image of a 35-year-old man with frequent PVCs and NSVT on Holter. Coronary CT angiography showed normal arteries. TTE showed mild biventricular dilatation suggesting arrhythmia-induced cardiomyopathy. Cine and LGE MR showed mild biventricular dilatation and midwall fibrosis within the interventricular septum (arrows), categorized as NICM. CMR findings were instrumental in the decision to perform and obtain a positive genetic testing for laminopathy. SAECG, signal-averaged electrocardiogram; RVOT, right ventricular outflow tract; PVC: premature ventricular contraction.

Figure 4

Example of ARVC diagnosis. A 20-year-old man with family history of premature sudden death in the brother. Pre-CMR workup retained a borderline ARVC diagnosis based on NSVT of RVOT morphology at exercise tesing, negative TTE, absence of repolarization or conduction abnormality on ECG, but positive late potentials on SAECG. Cine MR showed preserved RVEF, mild RV dilatation (103 mL/m²), and borderline wall motion abnormality on laterobasal and infero-basal RV (two-chamber view in A and four-chamber in B). Conventional LGE images were considered normal (C). Free-breathing LGE at higher spatial resolution showed focal fibrosis on infero-basal and laterobasal RV as well as on RVOT (arrows in D). The colocalization between fibrosis and the suspected wall motion abnormality was instrumental in retaining a minor Task Force Criterion for ARVC, fulfilling the criteria for definite ARVC diagnosis.

Figure 5

Examples of positive high-resolution LGE in otherwise negative patients. LGE of non-ischemic (arrows in A through D) and of ischaemic (in E through H) distribution are shown for eight patients. The arrythmia was NSVT in three (cases A, C, and E) and sustained VT in five (cases B, D, F, G, H). All of these patients had no prior history of SHD, negative TTE, cine MR and conventional LGE, and no obstructive CAD on coronary angiography. VT morphology was available in 5 cases (A, B, D, G, H) and matched substrate location in all five patients. Post-embolic microinfarction was suspected in (E) and (G) based on the documentation of AF episodes on 24 h Holter ECG. In the remaining six patients the aetiology remained uncertain.