Varied distributions of late gadolinium enhancement found among patients meeting cardiovascular magnetic resonance criteria for isolated left ventricular non-compaction

The study was conducted between April 2006 and January 2011 in our hospital. We enrolled 47 consecutive LVNC patients with first a diagnosis of LVNC. The diagnosis of LVNC was based on the presence of the following CMR and clinical criteria [14]: (a) appearance of 2 distinct myocardial layers; (b) prominent myocardial trabeculations and deep intertrabecular recesses communicating with the left ventricular cavity; (c) end-diastolic ratio of non-compacted-to-compacted(NC:C) myocardium >2.3:1, and (d) absence of other known co-existing cardiac abnormalities. Coronary artery disease (>50% diameter luminal stenosis in any of the major coronary arteries or the major coronary artery branches) was excluded by invasive coronary angiography in some but not all patients, according to the clinical judgment at the time of diagnosis by the clinical physician in this study. All patients gave informed consent, and the study was approved by the institutional ethics committee.

All CMR exams were performed using a 1.5-T unit (Avanto; Siemens Healthcare, Erlangen, Germany) with a high-performance gradient system (maximum gradient amplitude, 45 mT/m; maximum slew rate, 200 mT/m/ms). Twelve-element matrix coils (6 anterior and 6 posterior) equipped with the scanner and wireless vector electrocardiograph gating triggering were activated for data acquisition. All imaging acquisitions were captured under breath control. Scout transversal and sagittal images were acquired followed by a half-Fourier acquisition single shot turbo spin echo sequence (HASTE: repetition time/echo time [TR/TE] = 700/42 ms; voxel size = 2.5 × 1.5 × 6.0 mm; flip angle = 160°) for the exact determination of the long-axis, 4-chamber, and short-axis plane position. Retrospective electrocardiographic gating cine images were acquired in three long-axis views (LV two-chamber and four-chamber long-axis, and LV outflow tract) and a contiguous set of short-axis sections encompassing the entire LV using true fast imaging with steady-state free precession (TrueFISP: TR/TE = 40.0/1.1 ms; voxel size = 2.0 × 2.0 × 6.0 mm; flip angle = 62°). Fifteen ± 5 min after the injection of 0.2 mmol/kg of gadolinium-DTPA (Magnevist; Schering, Berlin, Germany) with an inversion-recovery sequence, the LGE images were obtained in a standard short axis view covering the entire ventricle, and in long axis views (horizontal and vertical long-axis and LV outflow tract).

All CMR data were transferred to a workstation (Siemens Medical Systems) for analysis. The LV end-diastolic diameter, LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction were calculated from the short axis cine images. The NC:C myocardium in diastole was calculated for each of the three long-axis views, and only the maximal ratio was used for analysis.

The presence or absence of LGE was qualitatively determined for each LV myocardial segment using the 17 segments model, according to the American Heart Association recommendation [15] by reviewing all short and long axis contrast-enhanced images. Patterns of LGE were defined as subendocardial, subepicardial, mid-myocardial, or transmural (≥75% of any segmental wall thickness) on visual analysis by a consensus of 2 independent observers.

The clinical characteristics of the entire group are summarized in Table 1. Forty-seven patients were considered to fulfil the imaging criteria of LVNC; the mean age was 39 ± 18 years (range, 13–78 years) and 37 (79%) were male. Of the 47 patients, 42 (89%) were severely symptomatic (New York Heart Association [NYHA] functional classes III and IV). All (n = 19; 100%) LGE (+) patients were in NYHA functional class III/IV. Comparing to LGE (-) patients, a non-significant trend towards an increasing percentage (n = 23; 82%) was observed (P = 0.07). In addition, LGE (+) patients had non-significantly lower LVEF, when compared with LGE (-) patients (23 ± 8 vs. 29 ± 15%; P = 0.06). Over 24-h ambulatory Holter ECG, premature ventricular contractions (PVCs) and non-sustained ventricular tachycardia (NSVT) were significantly more common in LGE (+) patients (PVCs: 79% vs. 29%; p = 0.001; and NSVT: 47% vs.7%; p = 0.003). The mean values of LV end-diastolic diameter, LV volumes, mass, number of non-compacted segments, and non-compacted/compacted ratio between the two groups was not statistically significant.

Three hundred fifty (44%) LV segments were considered to fulfil the definition of non-compaction; the mean number of LV non-compacted segments per patient was 7.4 ± 2.5 and the NC:C was 3.2 ± 0.7. Non-compaction was most commonly noted in the apical segments in all patients. Basal-septal segment involvement was not noted in any patient (Figure 1).

LGE was evident in 19 (40%) of the 47 patients. LGE was present in all 17 segments, not only involved non-compacted segments but also normal segments of the heart. Totally, 90(28%) LV segments showed LGE. Seventy-two (80%) LGE (+) LV segments were located in compacted segments, most commonly in the ventricular septum (n = 40; 44%), while only 18 (20%) LGE (+) LV segments were in non-compacted segments (Figure 2). The mean number of LGE (+) segments per patient was 5.1 ± 3.6. The distribution of LGE was subendocardial (n = 5; 6%), mid-myocardial (n = 61; 68%), subepicardial (n = 10; 11%), and transmural (n = 14; 15%) in total of 90 LGE (+) segments (Figure 3).

Our study has a number of limitations. It was conducted at a single center with a relatively small sample size, and the diagnosis was based on CMR cine appearances in relation to clinical findings. However, not all patients had coronary artery disease ruled out by invasive coronary angiography. More thorough documentation of all previous investigations and findings would have been desirable. Clinical follow-up data were not available so the relationship between LGE and prognosis in LVNC patients remains unknown.