Perioperative changes of the slope in the preload recruitable stroke work relationship by a single-beat technique after mitral valve surgery in functional mitral regurgitation with non-ischemic dilated cardiomyopathy

Abstract

Objectives The slope in the preload recruitable stroke work relationship is a highly linear, load-insensitive contractile parameter. However, the perioperative change of the slope has not been reported before. We examined the perioperative slope from a steady-state single beat in patients with functional mitral regurgitation and assessed the correlation with brain natriuretic peptide (BNP) levels. Methods The study included 16 patients with non-ischemic dilated cardiomyopathy and refractory heart failure: 10 patients underwent mitral valve plasty and left ventricular plasty (MVP\u2009+\u2009LVP group) and 6 patients who underwent mitral valve replacement and papillary muscle tugging approximation (MVR\u2009+\u2009PMTA group). The left ventricular ejection fraction was assessed by the modified Simpson method; the slope was assessed by the single-beat technique using transthoracic echocardiography. BNP levels were measured by chemiluminescent immunoassay. Results The left ventricular ejection fraction and slope did not significantly change from pre- to early post-surgery in the MVP\u2009+\u2009LVP group. Both the left ventricular ejection fraction and slope significantly increased 6\xa0months after surgery in the MVR\u2009+\u2009PMTA group. Postoperative BNP level was low in the MVR\u2009+\u2009PMTA group. While the postoperative left ventricular ejection fraction did not correlate with BNP levels, the postoperative slope significantly correlated with BNP level after surgery in the MVP\u2009+\u2009LVP group and in the total functional mitral regurgitation group. Conclusions The change of slope was dependent on surgical procedures. In functional mitral regurgitation, the slope may be a more sensitive parameter in reflecting the left ventricular contractile function than the left ventricular ejection fraction.