Before getting surgery for mitral regurgitation (MR), idiopathic cardiomyopathy patients who maintained systolic left ventricular (LV) torsion were the ones most likely to have good outcomes, according to a single-center study from Japan.
Patients whose hearts showed a normal wringing motion during contraction enjoyed more 2-year survival than their counterparts (87% versus 22% for a group lacking torsion versus 50% for those with left bundle branch block [LBBB], log-rank P<0.0002). The latter two groups shared similarly low survival rates.
At 2 years, a lower degree of LV torsion appeared to be a disadvantage for patients (6.1 degrees for survivors versus 2.0 degrees for nonsurvivors, P=0.018), reported Yuichi Notomi, MD, of The Keiyu Hospital in Japan, and colleagues in JACC: Basic To Translational Science.
The LBBB group, characterized by a wide QRS, was further divided into two groups; those getting cardiac resynchronization therapy (CRT) as a new therapy had better 2-year survival rates than those with prior CRT (67% versus 17%, log-rank P<0.006), despite a similar extent of heart twisting between the two arms.
“For patients with preserved LV torsion and a narrow QRS, mitral surgery seemed to be an acceptable option. Thus, the assessment of LV torsion may be useful for the prediction of post-mitral surgery outcomes in patients with a narrow QRS but not in those with a wide QRS, including patients with previous CRT implementation,” Notomi’s group concluded.
Only the preserved torsion group exhibited any reverse remodeling over the course of 2 years.
“Our results suggest the hypothesis that LV torsion may indicate the contractility/elastance (which enables reverse remodeling) of the LV compromised myocardium in [MR] patients,” Notomi’s group wrote.
“A heart with retained torsion might reflect a state in which such fiber disorientation has not yet occurred or is only minimally present, allowing for better recovery of function following treatment of the mitral regurgitation,” agreed David Burkhoff, MD, PhD, of Columbia University in New York, and Julius Guccione, PhD, of University of California San Francisco.
“Such a hypothesis has broad implications for predicting the likelihood of reverse remodeling following any treatment for heart failure, not just mitral surgery,” the pair wrote in a linked editorial.
In addition, Notomi and colleagues emphasized that “pre-operative LV size, ejection fraction, and geometric shape were not significantly different between 2-year survivors and nonsurvivors.”
The study included 50 consecutive patients with non-ischemic, chronic, secondary severe MR who underwent surgical mitral valve repair or replacement between 2006 and 2012. Researchers used echocardiography with 2-dimensional speckle tracking to assess torsion.
There were no deaths during the procedure. However, those with previous CRT were more likely to die within 2 years of mitral surgery (26% versus 3% for those receiving new CRT, P=0.024). Mortality was also more common for patients with a higher LV volume as estimated by the biplane disk summation (142 ml/m2 for nonsurvivors versus 124 ml/m2 for survivors, P=0.005).
According to the authors, their observational, single-center study was further limited by a small sample size and a short follow-up period. “The symptoms of many patients observed in this study might have been too severe (or too late) at the time of referral to surgery,” they added.
Yet Burkhoff and Guccione looked beyond those limitations and found a “potential utility of torsion in prognostication.”
“This parameter, along with other parameters, such as regional and global measurements of strain, have become more readily available through the use of 2- and 3-dimensional ultrasound speckle tracking,” the editorialists wrote.
The problem now is that the management of patients with idiopathic cardiomyopathy with severe MR is challenging. Guidelines are “mainly based on expert opinion rather than evidence,” they complained. “In particular, the role of mitral surgery, the type of mitral surgery, and patient baseline characteristics associated with clinical benefit remain unclear.”
Burkhoff and Guccione expressed optimism, however, that “as new, less-invasive interventional methods become available for treating mitral regurgitation, there will be the opportunity to treat a larger number of patients, particularly those who are more symptomatic and less likely to be treated surgically.”
“Efforts to identify patients most likely to benefit from such procedures is of prime importance.”
Notomi declared no relevant conflicting interests.
Burkhoff disclosed consulting for CardiacImplants, HeartWare, Corvia Medical, Sensible Medical, Impulse Dynamics, and BackBeat Medical.
Guccione reported consulting for Dassault Systemes.
JACC: Basic To Translational Science
Notomi Y, et al “Pre-operative left ventricular torsion, QRS width/CRT, and post-mitral surgery outcomes in patients with nonischemic, chronic, severe, secondary mitral regurgitation” JACC Basic Transl Sci 2016; DOI: 10.1016/j.jacbts.2016.04.006.
JACC: Basic To Translational Science
Burkhoff D, et al “A new twist on mitral regurgitation” JACC Basic Transl Sci 2016; DOI: 10.1016/j.jacbts.2016.05.005.