Objectives

Evaluation of cardiac function to optimize timing of surgical mitral valve repair (MVR) is difficult in the treatment of primary mitral regurgitation (PMR). Traditional echocardiographic parameters like left ventricular ejection fraction (LVEF) can be misleading due to an altered LV volume load. Therefore, the predictive value of speckle-tracking-echocardiography (STE) derived LV global longitudinal strain (GLS) remains to be investigated.

Methods

76 consecutive patients, who underwent isolated endoscopic MVR due to PMR were included. Patients were categorized to normal preoperative GLS (GLS≤-18%, n=35), and impaired GLS (GLS>-18%, n=41). Pre- and postoperative (5-8 days) transthoracic echocardiography (TTE) including STE measurements were performed and analyzed.

Results

Baseline patient characteristics, including outcome-relevant comorbidities and traditional TTE parameters like effective regurgitation orifice area (EROA), left ventricular end diastolic- and end systolic diameter and volume (LVEDD, LVESD, LVEDV, LVESV) were similar within both groups. Mean GLS was -20.6% and -15.2% in normal and impaired GLS group, while the difference of LVEF did not reach statistical significance (60.8±3.4% vs. 59.0±4.5%, p=0.098). NYHA functional class was similar, whereas serum level of proBNP was significantly lower in normal GLS group (274.6±38.6 vs. 1187.2±235.5 ng/L, p=0.001). In addition, the normal GLS group showed increased strain of left atrium and right ventricle (left atrial strain reservoir (LASr): 33.9±11.7% vs. 24.2±12.1%, p=0.001; right ventricular free wall longitudinal strain (RVFWSL): -28.5±5.8% vs. -23.8±8.3%, p=0.007). Postoperatively, LVEF was significantly higher in the normal compared to the impaired GLS group (51.1±5.9% vs. 45.2±5.9%, p<0.001). Furthermore, the number of patients with preserved postoperative LVEF >50%, was significantly higher in the normal GLS group (68.6% vs. 17.1%, p<0.001). Postoperative LV GLS was significantly reduced in both groups, but the normal GLS group still demonstrated superior GLS (-15.9±3.3% vs. -10.7±2.9%, p<0.001), LASr (19.2±7.4% vs. 13.7±6.6%, p=0.001), and RVFWSL (-20.8±5.5% vs. -16.0±5.5%, p<0.001).

Conclusion

In comparison to traditional TTE parameters such as LVEF, LV GLS has the potential to predict cardiac performance short-term after MVR in PMR patients. Therefore, STE seems to be a promising additional diagnostic tool to evaluate cardiac function and to help in decision-making for surgical timing.