Dataset related to the article 'Diagnostic Accuracy of Transillumination in Mitral Valve Prolapse: Side-by-Side Comparison of Standard Transthoracic Three-Dimensional Echocardiography against Surgical Findings'

This record contains raw data related to the article 'Diagnostic Accuracy of Transillumination in Mitral Valve Prolapse: Side-by-Side Comparison of Standard Transthoracic Three-Dimensional Echocardiography against Surgical Findings'

In patients with mitral valve (MV) prolapse (MVP) eligible for surgery, three-dimensional echocardiography (3DE) is routinely used for pre-operative assessment. Despite the worldwide use of transesophageal echocardiography in this context, transthoracic echocardiography (TTE) allows accurate noninvasive evaluation of MV anatomy and pathology in patients with good acoustic windows. Transillumination (TI) is a new 3D tool that improves the visualization of cardiac structures due to shadow effects achieved by the use of a virtual light source. We aimed to compare the diagnostic accuracy of TTE TI side-by-side with standard 3DE (s3DE) display in patients undergoing surgery for MVP, using surgical valve inspection as a reference standard.

We prospectively studied 59 patients with good acoustic windows on TTE, undergoing surgery for MVP. The study was approved by the institutional review board with a written informed consent. 3D MV analysis, including evaluation of scallops, chordal rupture and cleft was performed using s3DE and TI. Data were acquired by two experienced operators using zoomed acquisition mode over 4 to 6 cardiac cycles and processed by adjusting gain, brightness and smoothing. For TI images, the virtual light source was set in the left ventricle to enhance MV visualization. At the end of each TTE study, a first reader analyzed post-processed s3DE images and, one week later, the TI images. Surgical findings of MV anatomy were collected and agreement was expressed using Cohen’s concordance coefficient kappa, sensitivity, specificity, negative and positive predictive value (NPV, PPV) and overall accuracy. A second reader, blinded to all prior measurements, repeated TI analysis to assess reproducibility using intraclass correlation coefficients (ICC). 

No differences were noted in etiological diagnosis (Myxomatous vs Fibroelastic Deficiency) between the two 3DE techniques and surgery. Based on s3DE, 53 patients (90%) were diagnosed with P2 flail secondary to chordal rupture (N=51, 86%) or elongation (N=2, 14%). A cleft was diagnosed in 10 cases (17%), mostly located in the posterior leaflet. Based on TI, 53 patients (88%) were diagnosed with P2 flail secondary to chordal rupture (N=48, 81%) or elongation (N=5, 19%). In 9 patients (15%) a cleft was found, mainly located in the posterior leaflet.

The reproducibility of TI was good for prolapse detection (ICC=0.78) and chordal rupture localization (ICC= 0.73) and fair for cleft identification (ICC= 0.66). Overall, compared to the surgical reference, TI was significantly more accurate than s3DE for the identification of prolapse (94% vs 89%), chordal rupture (98% vs 92%) and cleft localization (87% vs 54%).

Specifically, s3DE correctly detected the flail in the majority of patients (N=57, 97%); in 20 patients (34%), at least one scallop was erroneously diagnosed as prolapsing, while in 4 patients (7%), a second prolapsing scallop was missed by s3DE. In 2 cases (3%) the real flail was missed. Agreement between s3DE and surgery in prolapse identification was poor (kappa=0.30).  By TI, the flail was correctly diagnosed in 57 cases (97%), while in 7 patients (12%) there was an over-diagnosis and in 4 cases (7%) an under-diagnosis. In 1 patient (2%), the flail was missed by TI. The agreement between TI and surgery in prolapse detection was considerably better (kappa=0.60). A significant difference (p<0.05) was found between s3DE and TI in sensitivity (87% vs 91%), specificity (92% vs 97%), PPV (75% vs 87%) and NPV (96% vs 98%) in scallop’s prolapse identification.

Chordal rupture was diagnosed in 51 patients (86%) by s3DE, compared to 45 (76%) cases confirmed by surgery. Among these 45 patients, s3DE correctly identified rupture position in 41 (91%). The agreement between s3DE and surgery was moderate (kappa=0.43). In contrast, TI identified chordal rupture in 48 cases (81%); among 45 patients confirmed by surgery TI detected the correct rupture position in 44 (98%), resulting in a very good agreement (kappa=0.86). Compared to s3DE, TI showed a significant difference (p<0.05) in sensitivity (89% vs 98%), specificity (95% vs 99%), PPV (74% vs 94%) and NPV (96% vs 99%) in chordal rupture recognition.

The agreement with surgery in terms of localization of cleft by s3DE was poor (k=0.17). Surgical valve inspection reported 8 cases (14%) with MV cleft (2 cleft of the anterior leaflet and 6 indentations of the posterior leaflet), only one was correctly diagnosed by s3DE, mainly due to signal drop-out. Concordance between TI and surgery in cleft localization was good (kappa=0.67); TI correctly diagnosed 6 out of 8 clefts. For cleft identification, sensitivity (13% vs 75%), specificity (96% vs 99%), PPV (10% vs 67%), and NPV (97% vs 99%) were significantly better (p<0.05) for TI compared to s3DE.

Based on our results, in patients undergoing surgery for MVP, TI has the potential to improve the diagnostic accuracy of TTE in anatomical analysis of the MV compared to s3DE, and may thus contribute towards improved personalized presurgical planning.