Materials and Methods
Between November 2008 and April 2021, all cases of cardiac surgery
performed at Nagoya Heart Center were screened, and patients
with preoperative
echocardiographic LVEF ≤30% were identified. Of these,
cases that underwent mitral valve
surgery due to secondary mitral valve regurgitation comprised the study
group. Cases with concomitant aortic valve surgery were excluded.
On echocardiographic evaluations,
cardiac chamber size was measured using the standard M-mode method, and
LVEF was calculated using the modified Simpson’s method. Valve
regurgitation was assessed using color-flow Doppler as “trivial”,
“mild”, “moderate”, or “severe”. Postoperative transthoracic
echocardiographic evaluation was performed on each patient before
discharge, usually on postoperative day 7.
Chronic obstructive pulmonary disease was defined as percentage
predicted forced expiratory volume in 1.0 s <75%, partial
pressure of oxygen in arterial blood <60 mmHg, or provision of
medical therapy. The definition of liver dysfunction was total bilirubin
≥1.5 mg/dl or liver enzymes (aspartate aminotransferase or alanine
aminotransaminase) ≥100 U/l. Clinical data were gathered from medical
records, operative records, and the in-hospital surgical database.
Long-term results were assessed by direct contact with the patients or
telephone interviews with the patients, their families, or their local
doctors. Survival was assessed between January and April 2021.
The primary endpoints for the early results were peri-operative
mortality and morbidity, and those for the long-term results were
mortality and hospitalization due to heart failure.
As the secondary endpoints, risk
factors for mortality in the long-term were examined.
Patients were divided into two
groups, and their long-term results were compared. The groups were
stratified as follows: sex, ischemic etiology, ejection fraction
<20%, clinical frailty scale score ≥4, presence of
hypertension, diabetes mellitus, hyperlipidemia, preoperative atrial
fibrillation, peripheral artery disease, hemodialysis, history of
smoking, percutaneous coronary intervention, myocardial infarction, main
procedural type (mitral valve replacement or plasty), and concomitant
procedures, including coronary artery bypass grafting, tricuspid valve
plasty, Maze procedure, and left ventricular restoration surgery.
Data were analyzed using SPSS version 22 statistical software (SPSS,
Chicago, IL). Results are expressed as means ± standard deviation.
Continuous data were analyzed using the Mann-Whitney U test ort- test as appropriate. Categorical data were analyzed using the
χ2 test. Survival analysis was performed using the
Kaplan-Meier method and the log-rank test. Results with values of
p<0.05 were considered significant.