EXPAND real-world outcomes: MitraClip NTR and XTR effective, well tolerated for primary mitral regurgitation
MitraClip NTR and XTR systems are effective and well tolerated for primary mitral regurgitation (MR), as shown in the prospective, multicentre, single-arm, international, post-marketing, real-world, observational EXPAND study presented at the American College of Cardiology 2020/World Congress of Cardiology (ACC.20/WCC) virtual meeting.
At 30 days following the procedure, the echocardiographic core laboratory (ECL)-adjudicated MR severity was reduced to none/trace level in 27.7 percent of primary MR patients, while MR ≤1+ and MR ≤2+ were achieved in 86.9 percent and 97.3 percent of patients, respectively. [Lim S, et al, ACC.20/WCC, abstract 412-12]
Since these results were confounded by a third of subjects (n=141) with MR ≤2+, the two groups were analyzed separately. “Of subjects with MR of ≥3+, 21 percent had no MR, 82.8 percent had MR of ≤1+ and 96.3 percent had MR ≤2+ 30 days after the procedure,” reported Professor Scott Lim of Division of Cardiovascular Medicine at University of Virginia, Virginia, US. “MR reduction to ≤1+ at 30 days was numerically greater in the EXPAND trial compared with the prohibitive risk cohort from the prior EVEREST studies, which used the same ECL and methodology.”
All-cause mortality was 2.4 percent (n=10). No myocardial infarctions were reported, while stroke occurred in 1.2 percent of patients (n=5) and non-elective cardiovascular surgery for device-related complications was required in 0.9 percent of study participants (n=4). Eight of the 12 device-related leaflet adverse events were due to single leaflet device attachment (SLDA), and one was due to leaflet injury, defined as a leaflet tear or perforation. Three SLDA events were inconclusive due to missing echocardiographic images at the time of panel review.
“In the relatively short period of 30 days following the procedure, left ventricular diameter volume saw a small but significant reduction from baseline [p range, <0.000–0.01],” noted Lim. “Larger, more clinically significant changes may be evident at longer-term follow-up, which is currently in progress.”
“As expected along with these results of significant MR reduction and ventricular remodelling, patients had improvements in quality of life and functional capacity, as measured by Kansas City Cardiomyopathy Questionnaire [KCCQ] score [mean 30-day score improvement from baseline, 19.8 points; p<0.001] and New York Heart Association [NYHA] class change [p<0.001],” observed Lim.
The ECL determined that in 28.5 percent of patients, the mechanisms of MR were complex, which was mainly due to presence of severely degenerative leaflets or wide flail gaps or widths, calcification in the landing zone, and presence of an extremely wide jet. “The finding reflects the difference in patients treated in the real world vs past clinical trials,” remarked Lim.
“MR reduction was achieved similarly in complex and non-complex anatomies,” noted Lim. “Greater MR reduction was achieved using the XTR than the NTR clip in complex anatomies [p=0.0383].”
The MitraClip system was approved by the US FDA in 2013 for the treatment of patients with primary (or degenerative) MR who are at prohibitive risk for mitral valve surgery.
“This study represents the first contemporary report of ECL- and clinical event committee-adjudicated 30-day clinical outcomes in patients with primary MR treated with the next-generation NTR and XTR MitraClips. It had a high procedural success rate, low procedure times, and short hospital stays,” concluded Lim. [J Am Coll Cardiol 2017;70:2315-2327]