This study screened hospitalized HOCM patients who underwent either the modified Morrow procedure alone or the combined procedure at Beijing Anzhen Hospital, Capital Medical University, between January 2022 and December 2024, using the Hospital Information System (HIS).

Inclusion criteria: (1) Diagnosed with HOCM (diagnostic criteria based on the “Chinese Guidelines for the Diagnosis and Treatment of Adult Hypertrophic Cardiomyopathy 2023”) [10, 11]; (2) Resting or provoked LVOT gradient $\ge$50 mmHg on transthoracic echocardiography; (3) Underwent the modified Morrow procedure with or without mitral valve surgery at our hospital; (4) Complete clinical data.

Exclusion criteria: (1) Echocardiography not meeting HOCM diagnostic criteria; (2) Incomplete echocardiographic data; (3) Missing other baseline data; (4) Comorbid severe hepatic or renal dysfunction, malignancy, mental illness, or incomplete clinical data.

Surgical indications and group allocation: All patients underwent the modified Morrow procedure for standard indications. Concomitant mitral valve surgery (repair) was performed based on predefined criteria: (1) moderate/severe MR (regurgitant jet area $\ge$4 cm²) not solely due to SAM; (2) intrinsic mitral valve pathology; or (3) significant residual MR/SAM on intraoperative transesophageal echocardiography (TEE) after myectomy. Patients with MR primarily related to SAM, expected to resolve after septal reduction, constituted the isolated procedure group.

Ultimately, 82 HOCM patients were enrolled and divided into two groups based on the surgical approach: the modified Morrow procedure alone group (n = 41) and the combined procedure group (n = 41). The Ethics Committee of Beijing Anzhen Hospital, Capital Medical University approved this study. All patients gave their informed consent in compliance with the principles of the Declaration of Helsinki.

All enrolled patients underwent baseline assessment within 24 hours of admission, and the following data were collected; three experienced clinicians and nurses independently reviewed the data to ensure accuracy: (1) Demographic and clinical baseline data: age, gender, height, body mass index, past medical history, and comorbidities.

(2) Echocardiographic parameters: Left atrial diameter (LAD), interventricular septum thickness (IVST), left ventricular end-diastolic volume (LVVd), left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), maximum velocity across the LVOT (Vmax), peak pressure gradient across the LVOT (PG), and MR severity.

(3) Perioperative data: Surgical approach, key operative parameters, length of hospital stay.

QoL assessment: The first visit at Beijing Anzhen Hospital in January 2022 was defined as the follow-up starting point. Follow-up was completed at 6 months postoperatively via outpatient review, telephone call, or re-hospitalization. The short form of the Kansas City cardiomyopathy questionnaire (KCCQ-12) was used to assess QoL before surgery and at 6 months postoperatively, covering domains such as symptoms, physical limitations, social limitations, and quality of life. Scores range from 0 to 100, with higher scores indicating better QoL.

SPSS version 26.0 (version number: 26.0.0.0, IBM Corp., Armonk, New York, USA) was used for statistical analysis. Normally distributed continuous data are presented as mean $\pm$ standard deviation (SD) and were compared between groups using independent samples t-tests. Categorical data are presented as numbers (percentages) and were compared using the Chi-square test. KCCQ scores before and after surgery constituted a repeated-measures design. Mauchly’s test of sphericity was performed first; if the assumption of sphericity was violated, the Greenhouse-Geisser correction was applied. Subsequently, a two-way repeated measures analysis of variance (ANOVA) was conducted, with “Time” (preoperative/postoperative 6 months) as the within-subjects factor and “Surgical Type” (isolated modified Morrow/combined procedure) as the between-subjects factor. Partial eta-squared ($\eta$²) was calculated to measure effect size. Simple effect analysis was used to interpret the time main effect when the interaction was not significant. A p-value 0.05 was considered statistically significant.

A total of 82 HOCM patients were enrolled and divided into the modified Morrow procedure alone group (n = 41) and the combined procedure group (n = 41), the combined procedure group consisted of patients undergoing isolated mitral annuloplasty, shown in Table 1. In the isolated procedure group, the mean age was 47.39 $\pm$ 12.27 years, with 26 males and 15 females, and a preoperative KCCQ score of 42.61 $\pm$ 16.72. In the combined procedure group, the mean age was 52.67 $\pm$ 11.71 years, with 25 males and 16 females, and a preoperative KCCQ score of 41.15 $\pm$ 15.16. There were no statistically significant differences between the two groups in age, gender, comorbidities, preoperative KCCQ score, or preoperative echocardiographic parameters (p $>$ 0.05). The only significant difference in baseline characteristics was that patients in the combined procedure group had more severe preoperative mitral regurgitation (7.30 $\pm$ 2.92 vs. 8.94 $\pm$ 3.21, p = 0.039).

As shown in Table 2, statistically significant differences were observed between the two groups in aortic cross-clamp time (Z = –3.080, p = 0.002) and cardiopulmonary bypass time (Z = –2.781, p = 0.005). The median aortic cross-clamp time was 150.0 min (127.0–182.0 min) in the combined procedure group and 113.8 min (100.5–144.3 min) in the isolated procedure group. The median cardiopulmonary bypass time was 122.0 min (102.0–178.0 min) and 80.0 min (80.0–122.0 min), respectively. However, no significant differences were found between the two groups in the duration of mechanical ventilation (Z = –1.346, p = 0.178), surgical time (Z = –1.218, p = 0.223), length of intensive care unit (ICU) stay (Z = –1.729, p = 0.084), or total hospital stay (Z = –0.796, p = 0.426). These results indicate that although the combined procedure required longer intraoperative times due to the additional handling of the mitral valve, it did not significantly prolong postoperative recovery time or hospitalization.

There were no significant differences between the two groups in postoperative KCCQ scores, LAD, IVST, LVVd, LVEF, LVFS, Vmax, PG, or MR at the 6-month follow-up (p $>$ 0.05). This indicates that the two surgical approaches were equivalent in improving cardiac function and QoL. Furthermore, comparisons of postoperative LAD, IVST, LVEF, LVFS, Vmax, PG, and MR degree between the combined procedure group and the isolated procedure group showed no significant differences (p $>$ 0.05), confirming that concomitant mitral valve intervention did not increase the risk of additional myocardial injury or obstruction. See Table 3 (Ref. [12]).

No significant intergroup difference was observed in preoperative KCCQ scores (p = 0.679). A significant postoperative improvement in KCCQ scores was noted in both the isolated (42.61 $\pm$ 16.72 to 57.76 $\pm$ 8.81) and combined (41.15 $\pm$ 15.16 to 57.56 $\pm$ 6.73) procedure groups (p 0.001 for both). The extent of improvement did not differ significantly between the two groups (p = 0.842, Table 4).

Further simple effect analysis showed that postoperative KCCQ scores increased significantly compared to preoperative scores in both groups (p 0.001), and there was no significant difference in postoperative KCCQ scores between the isolated Morrow procedure group and the combined procedure group (p = 0.842). This indicates that the change in postoperative KCCQ scores in HOCM patients was related to the surgery itself but not to the type of surgery. The estimated marginal means plot (Fig. 1) visually demonstrates that preoperative KCCQ scores were similar between the groups, both increased significantly postoperatively, and the curves nearly overlap, verifying the comparable effectiveness of the two surgical approaches in improving KCCQ scores and the lack of difference in KCCQ score improvement between the two surgical strategies for HOCM patients.

Fig. 1.

Estimated marginal means of KCCQ scores from the pre- to postoperative period, by group. KCCQ, Kansas City cardiomyopathy questionnaire.

Univariate and multivariate linear regression analyses were performed to explore factors associated with postoperative KCCQ score. Univariate analysis showed that preoperative interventricular septum thickness (IVST) was significantly associated with improvement in postoperative KCCQ score (p = 0.019). After adjusting for gender, age, preoperative KCCQ grade, and left ventricular structural and functional parameters in the multivariate analysis, IVST remained an independent predictor (p = 0.040) (Table 5). The results indicated that greater preoperative interventricular septum thickness was associated with higher postoperative KCCQ scores, and the difference was statistically significant.

The results of this study show that KCCQ scores significantly improved at the 6-month follow-up in HOCM patients, regardless of whether they underwent the isolated modified Morrow procedure or the combined procedure (p 0.001). The average increase exceeded 15 points, surpassing the minimal clinically important difference threshold for this scale, suggesting improvements in subjective symptoms, physical function, and QoL in both groups, which is also confirmed by domestic research [7]. Univariate and multivariate logistic regression analyses exploring factors associated with postoperative KCCQ scores indicated that greater preoperative interventricular septum thickness predicted higher postoperative KCCQ scores. The significant increase in postoperative KCCQ scores in both groups of this study is consistent with previous findings, confirming that the modified Morrow procedure is an effective means of improving QoL in HOCM patients [13]. The improvement in MR after isolated myectomy is primarily attributable to the relief of SAM following septal reduction, which restores normal mitral valve function [2]. Whether or not combined with Mitral valve surgery, the procedure only increased the Operative times and did not translate into longer Hospital stay, Duration of mechanical ventilation, or ICU stay for the patients. Interestingly, greater preoperative IVST predicted better postoperative KCCQ scores. This may reflect that more severe septal hypertrophy allows for greater hemodynamic and symptomatic improvement after successful myectomy. Statistical collinearity with other severity markers should also be considered. This finding suggests that significant hypertrophy does not diminish the potential for substantial quality-of-life gain following surgery.

From a clinical management perspective, although early postoperative KCCQ scores did not differ between the combined surgery group and the isolated surgery group, the particularity of the former lies in the need for long-term anticoagulation (especially lifelong for those with mechanical valve replacements), stricter long-term monitoring of mitral valve function, and more stringent heart rate control. While these factors did not manifest as differences in KCCQ scores at 6 months, they are crucial for influencing long-term QoL and clinical outcomes. It is essential to construct a comprehensive management process tailored to their characteristics of “high long-term anticoagulation needs, stringent heart rate monitoring requirements, and need for long-term mitral valve function follow-up”.

Furthermore, the KCCQ, as a heart failure-specific tool, has been proven sensitive to perioperative interventions. Research by Sherrod et al. [9] showed that every 10-point increase in the KCCQ overall summary score is associated with an 18% reduction in the risk of heart failure hospitalization or death within one year. For combined surgery patients, irregular anticoagulation or significant heart rate fluctuations might offset the KCCQ improvement gained from surgery and even increase the risk of thrombosis/bleeding. Therefore, clinical management should not stop at the conclusion of “no difference in early postoperative KCCQ”. Instead, it must address the long-term management challenges specific to combined surgery patients. In clinical practice, using a “disease journey map” as a framework, precisely recording MR baseline and coagulation function preoperatively, managing international normalized ratio (INR) postoperatively via a “Valve Anticoagulation e-Assistant”, monitoring heart rate with wearable devices, and leveraging mini-programs and official accounts after discharge to achieve intelligent transitional care encompassing “anticoagulation self-management-KCCQ score tracking - re-examination reminders” are crucial. This ultimately forms a closed-loop “Assessment-Intervention-Monitoring-Follow-up” management system, building a management framework centered on “intelligent tools + full-process closed-loop” to continuously safeguard the QoL and long-term prognosis of patients undergoing combined mitral valve surgery.

The combined procedure was associated with longer aortic cross-clamp and cardiopulmonary bypass times. Although no significant increase in early postoperative complications was observed in this cohort, extended operative and perfusion time may elevate the risk of neurological, respiratory, and inflammatory complications. This underscores the importance of meticulous intraoperative management and postoperative monitoring in patients undergoing combined surgery. Future studies with larger samples and longer follow-up are needed to better evaluate the safety profile of the combined approach.