Mitral regurgitation carries greater prognostic significance than mitral stenosis in patients undergoing transcatheter aortic valve replacement.

AIMS: This study assessed the outcomes of concomitant mitral valve disease and severe aortic stenosis in patients undergoing transcatheter aortic valve replacement (TAVR). METHODS: Echocardiographic data of 813 patients with severe aortic stenosis undergoing transfemoral TAVR were collected, and clinical outcomes were analyzed for individuals with mitral stenosis and mitral regurgitation. RESULTS: The final cohort includes 788 patients with severe calcific aortic stenosis. Among single parameters of mitral stenosis, a smaller baseline mitral valve area (MVA) by the continuity equation and higher postprocedural mean mitral gradients (MMG) were associated with an increased risk of death at 1 year (P-values 0.02 and <0.01, respectively), but no correlation with outcomes was demonstrated after multivariate adjustment for major prognosticators. Mitral stenosis (based on MVA + MMG) was not associated with complications or mortality. Mitral regurgitation was present in 94.6% of the population at baseline and regressed by at least one grade post-TAVR in 28% of the patients. The improvement in mitral regurgitation was associated with a greater prosthetic effective orifice area (P-value 0.03). Significant (at least moderate) residual mitral regurgitation was correlated with short-term complications and shown to be an independent predictor of 1-year mortality (P-value 0.02, odds ratio (OR) 5.37, confidence interval 1.34-21.5). CONCLUSION: Mitral regurgitation has a greater impact on TAVR patients than mitral stenosis as assessed by functional methods.

Challenges of managing anomalous mitral arcade with severe mitral regurgitation and hydrops fetalis in infants.

Anomalous mitral arcade (MA) is a rare congenital anomaly. We report a case of MA in a newborn who presented with hydrops fetalis due to severe mitral regurgitation. After birth, he developed severe respiratory failure, congestive heart failure and airway obstruction because an enlarged left atrium from severe mitral regurgitation compressed the distal left main bronchus. There is limited experience in surgical management of this condition in Thailand, and the patient's mitral valve was too small for replacement. Therefore, he was treated with medication to control heart failure and supported with positive pressure ventilation to promote growth. We have followed the patient until the current time of writing this report at the age of 2 years, and his outcome is favourable regarding heart failure symptoms, airway obstruction, growth and development. This case describes a challenging experience in the non-surgical management of MA with severe regurgitation, which presented at birth.

Iatrogenic non-coronary leaflet perforation as a complication after robotic mitral valve repair.

Iatrogenic aortic regurgitation secondary to leaflet injury is a rare complication of mitral valve surgery. For the first time, we report a patient who had progressive aortic regurgitation due to non-coronary leaflet perforation after robotic mitral valve repair and required aortic valve repair 18 months after this initial surgery. As in our case, aortic regurgitation after mitral valve surgery may remain undiagnosed on intraoperative transesophageal echocardiography or undetected until the patient's discharge due to gradual enlargement of very small perforations over the postoperative course.

Mitral Annular Disease at Cardiac MRI: What to Know and Look For.

Accurate evaluation of the mitral valve (MV) apparatus is essential for understanding the mechanisms of MV disease across various clinical scenarios. The mitral annulus (MA) is a complex and crucial structure that supports MV function; however, conventional imaging techniques have limitations in fully capturing the entirety of the MA. Moreover, recognizing annular changes might aid in identifying patients who may benefit from advanced cardiac imaging and interventions. Multimodality cardiovascular imaging plays a major role in the diagnosis, prognosis, and management of MV disease. Transthoracic echocardiography is the first-line modality for evaluation of the MA, but it has limitations. Cardiac MRI (CMR) has emerged as a robust imaging modality for assessing annular changes, with distinct advantages over other imaging techniques, including accurate flow and volumetric quantification and assessment of variations in the measurements and shape of the MA during the cardiac cycle. Mitral annular disjunction (MAD) is defined as atrial displacement of the hinge point of the MV annulus away from the ventricular myocardium, a condition that is now more frequently diagnosed and studied owing to recent technical advances in cardiac imaging. However, several unresolved issues regarding MAD, such as the functional significance of pathologic disjunction and how this disjunction advances in the clinical course, require further investigation. The authors review the role of CMR in the assessment of MA disease, with a focus on MAD and its functional implications in MV prolapse and mitral regurgitation. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Stojanovska and Fujikura in this issue.

Technical and Clinical Outcomes After Transcatheter Edge-to-Edge Repair of Mitral Regurgitation in Male and Female Patients: Is Equality Achieved?

BACKGROUND: Currently, no clear impact of sex on short- and long-term survival following transcatheter edge-to-edge mitral valve repair (TEER) is evident, although no data are available on postprocedural life expectancy. Our aim was to assess sex-specific differences in outcomes of patients with mitral regurgitation (MR) treated by TEER. METHODS AND RESULTS: Short-term and 5-year outcomes in men and women undergoing TEER between 2011 and 2018 who were included in the large, multicenter, real-world MitraSwiss registry were analyzed. Outcomes were compared stratified by sex and according to MR cause (primary versus secondary). The impact of TEER on postprocedural life expectancy was estimated by relative survival analysis. Among 1142 patients aged 60 to 89 years, 39.8% were women. They were older, with fewer cardiovascular risk factors and lower functional capacity compared with men. Thirty-day mortality was higher in men than in women (3.3% versus 1.1%; odds ratio, 3.16 [95% CI, 1.16-10.7]; P=0.020). Five-year survival was comparable in both sexes (adjusted hazard ratio for 5-year mortality in men, 1.14 [95% CI, 0.90-1.44], P=0.275). Both men and women with either primary or secondary MR showed similar clinical efficacy over time. TEER provided high relative survival estimates among all groups, and fully restored predicted life expectancy in women with primary MR (5-year relative survival estimate, 97.4% [95% CI, 85.5-107.0]). CONCLUSIONS: TEER is not associated with increased short-term mortality in women, whereas 5-year outcomes are comparable between sexes. Moreover, TEER completely restored normal life expectancy in women with primary MR. A residual excess mortality persists in secondary MR, independently of sex.

A review regarding the article 'Comparative efficacy and safety of mitral valve repair versus mitral valve replacement in Rheumatic heart disease: A high-value care systematic review and meta-analysis'.

Rheumatic heart disease remains a major cause of cardiovascular death worldwide. Limited real-world nationwide data are available to compare the long-term outcomes between mitral valve repair and replacement in rheumatic heart disease. For patients with RHD, MVP is the superior choice of surgical intervention owing to better long-term survival, reduced incidence of early mortality and thromboembolic events. However, it entails higher chances of re-operation at follow-up at four, eight and twelve years. Although feasible, surgeons may opt for MVR in patients with a worse prognosis. Whereas degenerative mitral repair for severe MR has been proven superior to replacement, the optimal operative strategy for mitral RHD remains unclear. In developing countries, mitral RHD commonly develops in young patients, predominantly consists of MR rather than MS, and occurs more frequently than in the United States. In addition, the predominant MR etiology (rather than MS), relatively early intervention in the RHD timeline, and variation in Carpentier MR types among developing world populations further make these rheumatic MVs more amenable to repair than replacement. Patients should be carefully selected for mitral valve repair because of its higher reoperation rate, particularly those with previous percutaneous transvenous mitral commissurotomy. Careful assessment of anterior leaflet mobility/calcification to determine mitral repair or replacement was associated with improved outcomes. This decision-making strategy may alter the threshold for rheumatic mitral replacement in the current valve-in-valve era.

Long-term outcomes comparison of mitral valve repair or replacement for secondary mitral valve regurgitation. An updated systematic review and reconstructed time-to-event study-level meta-analysis.

BACKGROUND AND AIM: The ideal surgical intervention for secondary mitral regurgitation (SMR), a disease of the left ventricle not the mitral valve itself, is still debated. We performed an updated systematic review and study-level meta-analysis investigating mitral valve repair (MVr) versus mitral valve replacement (MVR) for adult patients with SMR, with or without coronary artery disease (CAD). METHODS: PubMed, CENTRAL and EMBASE were searched for studies comparing MVr versus MVR. Randomized trial or observational studies were considered eligible. Primary endpoint was long-term mortality for any cause. Kaplan-Meier survival curves were reconstructed and compared with Cox linear regression. Landmark analysis and time-varying hazard ratio (HR) were analyzed. Sensitivity analyses included meta-regression and separate sub-analysis. A random effects model was used. RESULTS: Twenty-three studies (MVr=3,727 and MVR=2,839) were included. One study was a randomized trial, and 19 studies were adjusted. The mean weighted follow-up was 3.7±2.8 years. MVR was associated with significative greater late mortality (HR=1.26; 95 % CI, 1.14-1.39; P<0.0001) at 10-year follow-up. There was a time-varying trend showing an increased risk of mortality in the first 2 years after MVR (HR=1.38; 95 % CI, 1.21-1.56; P<0.0001), after which this difference dissipated (HR=0.94; 95 % CI, 0.81-1.09; P=0.41). Separate sub-analyses showed comparable long-term mortality in patients with concomitant coronary surgery ≥90 %, left ventricle ejection fraction ≤40 %, and sub-valvular apparatus preservation rate of 100 %. CONCLUSIONS: Compared to repair, MVR is associated with higher probability of mortality in the first 2 years following surgery, after which the two procedures showed comparable late mortality rate.

Understanding transcatheter edge-to-edge repair "knobology": Advanced catheter steering for different scenarios of transseptal puncture.

Following the introduction in the latest European and American guidelines, transcatheter edge-to-edge repair has become a valid alternative to surgery for ineligible patients. Among the available technologies, MitraClip (Abbott) was the first to be introduced for the percutaneous treatment of mitral regurgitation with the edge-to-edge technique. Although its safety and effectiveness has been widely demonstrated, the optimal procedural results are highly dependent from operators' experience. In this manuscript, we provide a full guide of advanced steering maneuvers of MitraClip in different scenarios of transseptal puncture.

Transcatheter Mitral Valve Repair With the MitraClip Device for Prior Mitral Valve Repair Failure: Insights From the GIOTTO-FAILS Study.

BACKGROUND: Minimally invasive mitral valve repair has a favorable risk-benefit profile in patients with significant de novo mitral regurgitation. Its role in patients with prior mitral valve repair is uncertain. We aimed to appraise the outcome of patients undergoing transcatheter edge-to-edge repair (TEER) with prior transcatheter or surgical mitral valve repair (SMVR). METHODS AND RESULTS: We queried the Italian multicenter registry on TEER with MitraClip, distinguishing naïve patients from those with prior TEER or (SMVR). Inhospital and long-term clinical/echocardiographic outcomes were appraised. The primary outcome was the occurrence of death or rehospitalization for heart failure. A total of 2238 patients were included, with 2169 (96.9%) who were naïve to any mitral intervention, 29 (1.3%) with prior TEER, and 40 (1.8%) with prior SMVR. Several significant differences were found in baseline clinical and imaging features. Respectively, device success was obtained in 2120 (97.7%), 28 (96.6%), and 38 (95.0%, P=0.261) patients; procedural success in 2080 (95.9%), 25 (86.2%), and 38 (95.0%; P=0.047); and inhospital death in 61 (2.8%), 1 (3.5%), and no (P=0.558) patients. Clinical follow-up after a mean of 14 months showed similar rates of death, cardiac death, rehospitalization, rehospitalization for heart failure, and their composite (all P>0.05). Propensity score-adjusted analysis confirmed unadjusted analysis, with lower procedural success for the prior TEER group (odds ratio, 0.28 [95% CI, 0.09-0.81]; P=0.019) but similar odds ratios and hazard ratios for all other outcomes in the naïve, TEER, and SMVR groups (all P>0.05). CONCLUSIONS: In carefully selected patients, TEER can be performed using the MitraClip device even after prior TEER or SMVR.

Retrospective evaluation of the utility of shock index to determine the presence of congestive heart failure in dogs with myxomatous mitral valve disease (2019-2021): 98 cases.

OBJECTIVES: To calculate the shock index (SI) in dogs with myxomatous mitral valve disease (MMVD) and to evaluate its use to predict the presence of congestive heart failure (CHF). DESIGN: Retrospective study. SETTING: Small animal university veterinary teaching hospital. ANIMALS: Ninety-eight dogs with MMVD and 20 healthy dogs as part of a control group. INTERVENTIONS: Heart rate (HR) and systolic blood pressure (SBP) were recorded, and SI was calculated by dividing HR by SBP for each dog. MEASUREMENTS AND MAIN RESULTS: The mean (SD) HR, SBP, and SI were 123/min (32.6), 147 mm Hg (21.5), and 0.86 (0.3), respectively, for dogs with MMVD and 98/min (20.9), 145 mm Hg (18.7), and 0.68 (0.13), respectively, for control dogs. Dogs with MMVD had a significantly higher HR compared with control dogs (P < 0.01), and an elevation in HR was seen as the severity of MMVD increased. Dogs in stage B2 and C/D MMVD had a significantly higher SI value compared with control dogs (P = 0.04 and P < 0.01, respectively). SI was significantly higher in dogs in stage C/D MMVD compared with dogs in stage B2 MMVD (P < 0.01). Ten of 98 (10%) dogs had an arrhythmia. HR, SBP, and SI were not significantly different between dogs with and without arrhythmias (P = 0.13, P = 0.57, and P = 0.07, respectively), but significantly more dogs with CHF had an arrhythmia (P = 0.01). SI (area under the curve [AUC]: 0.98) and HR (AUC: 0.95) were excellent indicators for the presence of CHF. An optimal SI cutoff value ≥1.1 had 92% sensitivity and 95% specificity for predicting the presence of CHF, and an optimal HR cutoff value of ≥157/min had 92% sensitivity and 93% specificity for the prediction of CHF. CONCLUSIONS: When there are compatible clinical signs, SI values ≥1.1 may suggest the presence of CHF in dogs with MMVD.

Significant Mitral Regurgitation After Permanent Right Ventricular Pacemaker Implantation: Prognostic Implications.

The underlying mechanisms leading to the development of mitral regurgitation (MR) after right ventricular (RV) pacemaker (PM) implantation and its prognostic value have yet to be fully understood. The purpose of this study was to evaluate the prevalence and clinical variables associated with the development of MR after RV pacing and its association with outcomes. A total of 451 patients (mean age 69 ± 15 years, 61% male) who underwent de novo RV PM implantation were included. The development of significant MR, defined as ≥moderate from mild or none/trace at baseline, occurred in 131 (29%) patients at a median of 2.4 years (interquartile range: 1.0 to 3.8 years) after PM implantation. Multivariate logistic regression analysis demonstrated that implantation of a single-chamber PM, left ventricular end-systolic volume index, and the presence of mild MR (vs no MR) at baseline were independently associated with the development of significant MR post-implant. Cardiac events, defined as the composite of all-cause mortality or heart failure hospitalization, occurred in 143 patients (31.7%) during a median follow-up of 5.4 years (interquartile range: 3.0 to 8.1 years). Multivariate Cox regression analysis demonstrated that the development of significant MR was independently related to the occurrence of cardiac events. In conclusion, the development of significant MR after PM implantation is seen in about one-third of recipients and is independently associated with adverse cardiac events.

Percutaneous Coronary Intervention as a Non-Surgical Treatment for Ischemic Mitral Regurgitation in Patients with Multi-Vessel Coronary Artery Disease.

BACKGROUND Multi-vessel coronary artery disease (MVD) represents a severe type of coronary artery disease (CAD). Ischemic mitral regurgitation (IMR) is a common mechanical complication in patients with CAD. This study aimed to retrospectively investigate the efficacy of percutaneous coronary intervention (PCI) on moderate/severe IMR in patients with MVD. MATERIAL AND METHODS Clinical data were collected from 15 patients who underwent successful treatment for MVD combined with moderate/severe IMR through the PCI procedure and achieved complete revascularization between January 2014 and December 2022. Cardiac structural and functional parameters were assessed through echocardiographic evaluations. Color flow recordings of MR jets were obtained through an enlarged view of the 4-chamber cut, and the diagnosis of MR was categorized into mild (<4 cm²), moderate (4-8 cm²), and severe (>8 cm²), based on the MR area. RESULTS The common features of the selected cases were advanced age, low body weight, and renal insufficiency. Cardiac echocardiography revealed an augmentation in the left atrial anteroposterior diameter and left ventricular internal diameter at end-systole after PCI, while the left ventricle internal diameter in diastole, left ventricular ejection fraction, and left ventricular fractional shortening were comparable to preoperative values. All patients had moderate/severe MR preoperatively, and MR improved at 1 month (2.73±0.69) and 12 months (2.26±0.58) after PCI. CONCLUSIONS In cases of MVD accompanied by moderate/severe IMR, undergoing PCI can spare certain elderly patients with low body weight and renal insufficiency from high-risk surgery, alleviating the severity of MR without undergoing mitral valve intervention.

Five-year outcomes of different techniques for minimally invasive mitral valve repair in Barlow's disease.

OBJECTIVES: Barlow's disease is a specific sub-form of mitral valve (MV) disease, characterized by diffuse excessive tissue and multi segment prolapse. The anterolateral mini-thoracotomy represents the standard access for MV regurgitation in many centres. It still remains unclear which surgical technique provides the best results. Therefore, the aim of this study was to compare operative safety and mid-term outcomes after (i) isolated annuloplasty, (ii) use of additional artificial chordae or (iii) leaflet resection in patients suffering from Barlow's disease undergoing minimally invasive MV repair. METHODS: A consecutive series of patients suffering from Barlow's disease undergoing minimally invasive MV surgery between 2001 and 2020 were analysed (n = 246). Patients were grouped and analysed according to the used surgical technique. The primary outcome was a modified Mitral Valve Academic Research Consortium combined end-point of mortality, reoperation due to repair failure or reoccurrence of severe mitral regurgitation within 5 years. The secondary outcome included operative success and safety up to 30 days. RESULTS: No significant difference was found between the 3 surgical techniques with regard to operative safety (P = 0.774). The primary outcome did not differ between groups (P = 0.244). Operative success was achieved in 93.5% and was lowest in the isolated annuloplasty group (77.1%). Conversion to MV replacement was increased in patients undergoing isolated annuloplasty (P < 0.001). CONCLUSIONS: Isolated annuloplasty, use of additional artificial chordae and leaflet resection represent feasible techniques in Barlow patients undergoing minimally invasive MV surgery with comparable 5-year results. In view of the increased conversion rate in the annuloplasty group, the pathology should not be oversimplified.

Ertugliflozin for Functional Mitral Regurgitation Associated With Heart Failure: EFFORT Trial.

BACKGROUND: The morbidity and mortality rates of patients with heart failure (HF) and functional mitral regurgitation (MR) remain substantial despite guideline-directed medical therapy for HF. We evaluated the efficacy of ertugliflozin for reduction of functional MR associated with HF with mild to moderately reduced ejection fraction. METHODS: The EFFORT trial (Ertugliflozin for Functional Mitral Regurgitation) was a multicenter, double-blind, randomized trial to examine the hypothesis that the sodium-glucose cotransporter 2 inhibitor ertugliflozin is effective for improving MR in patients with HF with New York Heart Association functional class II or III, 35%≤ejection fraction<50%, and effective regurgitant orifice area of chronic functional MR >0.1 cm2 on baseline echocardiography. We randomly assigned 128 patients to receive either ertugliflozin or placebo in addition to guideline-directed medical therapy for HF. The primary end point was change in effective regurgitant orifice area of functional MR from baseline to the 12-month follow-up. Secondary end points included changes in regurgitant volume, left ventricular (LV) volume indices, left atrial volume index, LV global longitudinal strain, and NT-proBNP (N-terminal pro-B-type natriuretic peptide). RESULTS: The treatment groups were generally well-balanced with regard to baseline characteristics: mean age, 66±11 years; 61% men; 13% diabetes; 51% atrial fibrillation; 43% use of angiotensin receptor-neprilysin inhibitor; ejection fraction, 42±8%; and effective regurgitant orifice area, 0.20±0.12 cm2. The decrease in effective regurgitant orifice area was significantly greater in the ertugliflozin group than in the placebo group (-0.05±0.06 versus 0.03±0.12 cm2; P<0.001). Compared with placebo, ertugliflozin significantly reduced regurgitant volume by 11.2 mL (95% CI, -16.1 to -6.3; P=0.009), left atrial volume index by 6.0 mL/m2 (95% CI, -12.16 to 0.15; P=0.005), and LV global longitudinal strain by 1.44% (95% CI, -2.42% to -0.46%; P=0.004). There were no significant between-group differences regarding changes in LV volume indices, ejection fraction, or NT-proBNP levels. Serious adverse events occurred in one patient (1.6%) in the ertugliflozin group and 6 (9.2%) in the placebo group (P=0.12). CONCLUSIONS: Among patients with functional MR associated with HF, ertugliflozin significantly improved LV global longitudinal strain and left atrial remodeling, and reduced functional MR. Sodium-glucose cotransporter 2 inhibitors may be considered for patients with functional MR. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04231331.

The hybrid (physical-computational) cardiovascular simulator to study valvular diseases.

To better understand the impact of valvular heart disease (VHD) on the hemodynamics of the circulatory system, investigations can be carried out using a model of the cardiovascular system. In this study, a previously developed hybrid (hydro-numerical) simulator of the cardiovascular system (HCS) was adapted and used. In our HCS Björk-Shiley mechanical heart valves were used, playing the role of mitral and aortic ones. In order to simulate aortic stenosis (AS) and mitral regurgitation (MR), special mechanical devices have been developed and integrated with the HCS. The simulation results proved that the system works correctly. Namely, in the case of AS - the mean pulmonary arterial pressure was increased due to increased preload of the left ventricle and the decrease in right ventricular preload was caused by a decrease in systemic arterial pressure. The severity of AS was performed based on the transaortic pressure gradient as well as using the Gorlin and Aaslid equations. In the case of severe AS, when the mean gradient was above 40 mmHg, the aortic valve orifice area was 0.5 cm2, which is in line with ACC/AHA guidelines. For the case of MR - with increasing severity of MR, there was a decrease in the left ventricular pressure and an increase in left atrial pressure. Using mechanical heart valves to simulate VHD by the HCS can be a valuable tool for biomedical research, providing a safe and controlled environment to study and understand the pathophysiology of VHD.

In vivo mitral valve repair for the transplanted donor heart in orthotopic heart transplantation.

A 53-year-old woman with the dilated phase of hypertrophic cardiomyopathy underwent orthotopic heart transplantation. The donor heart was evaluated as normal preoperatively without mitral regurgitation or the left atrium dilation, transplanted using the modified bicaval technique. Although the heart beat satisfactorily after aortic declamping, massive mitral regurgitation was observed without any prolapse or annular dilation. Because of the difficulty in weaning from cardiopulmonary bypass, a second aortic cross-clamp was applied, and we detached the inferior vena cava and the right side of the left atrial anastomosis to approach the mitral valve, obtaining a satisfactory exposure. No abnormalities were observed in the mitral valve leaflets, annulus or subvalvular apparatus. Subsequent in vivo mitral annuloplasty using prosthetic full ring successfully controlled the regurgitation, and the patient was easily weaned from cardiopulmonary bypass. She discharged to home with good mitral valve and cardiac functions. And the patient has been doing well without any recurrence of MR or heart failure for over a year after surgery.

Iron parameters analysis in dogs with myxomatous mitral valve disease.

BACKGROUND: Myxomatous mitral valve disease (MMVD) is the most common acquired cardiovascular disease in small breed dogs. In contrast to human patients with heart failure (HF), iron deficiency (ID) prevalence in dogs with MMVD is weakly known. The study aimed to assess the usability of ID markers in serum and reticulocyte parameters from whole blood of dogs with MMVD to evaluate early ID symptoms. RESULTS: Sixty-eight dogs (43 male and 25 female) were included in the study. MMVD dogs were assigned according to the 2019 ACVIM guidelines for groups B1 (n = 9), B2 (n = 10), C (n = 27) and D (n = 10). Groups were also combined into B1 and B2 as non-symptomatic HF and C with D as symptomatic HF. Healthy controls were 12 dogs. Serum iron concentration below the reference range in dogs with MMVD was 12.5%. Other ID indices, such as %SAT, UIBC, and TIBC were similar in the MMVD groups and healthy controls (p > 0.05 for all parameters). Statistical comparison between control group and 4 groups of different stages of MMVD showed that significant differences occur only in serum transferrin. The assessment of ferritin and soluble transferrin receptors using Western Blotting did not show differences between control (n = 7) and MMVD (n = 33) dogs. Study has shown positive correlation between ID parameters and echocardiographic indices such as LA/Ao and LVIDdN, and some biochemical parameters. A significant increase in reticulocytes percentage, assessed manually, was observed in the HF group of animals (p = 0.027) compared to the control group. CONCLUSIONS: Studies have shown that ID parameters in serum are not significantly different in dogs with MMVD compared to healthy dogs. However, there is a clear correlation between atrial size and normalised left ventricular size to body size and some biochemical parameters, including ID parameters and therefore the severity of MMVD.