Percutaneous Mitral Valve Repair With MitraClip in Inoperable Patients With Severe Mitral Regurgitation Complicated by Cardiogenic Shock

Abstract: Background. Severe mitral regurgitation (MR) complicated by cardiogenic shock has high operative mortality. Percutaneous leaflet repair with MitraClip (Abbott Vascular) is a less invasive alternative to surgery. The effectiveness and safety of this approach is unknown. Methods. We retrospectively analyzed procedural characteristics of shock patients with severe MR treated with MitraClip in a tertiary, high-volume program (Abbott Northwestern Hospital, Minneapolis, Minnesota) during 2010-2019. The primary outcome of the study was 30-day survival free of significant MR (grade ≤2). One-year mortality was a secondary outcome. Results. Among 322 patients who underwent MitraClip implantation during the study period, 11 inoperable patients with severe MR and cardiogenic shock were included in this analysis. Mean patient age was 74 ± 11 years and 54% were male. The mechanism of MR was degenerative in 7 patients (63.6%) and functional in 4 patients (36.4%), including 1 post myocardial infarction, 1 with chronic ischemic heart disease, and 2 with end-stage non-ischemic cardiomyopathy. Hemodynamic support with intra-aortic balloon pump was used in 5 patients (45%). The A2-P2 scallop was the more common location for MitraClip insertion, and 27% of patients had >1 clip implanted. Median fluoroscopy time was 18.5 minutes (interquartile range [IQR], 10-22 minutes) and mean postprocedure gradient was 4.5 mm Hg (IQR, 3-5 mm Hg). At 30 days, eight patients (72.7%) were alive with MR grade ≤2. At 1 year, mortality was 66%, and was driven mainly by non-cardiac causes. Conclusions. Among inoperable patients with severe MR and cardiogenic shock, percutaneous leaflet repair with MitraClip is associated with acceptable short-term effectiveness.

J INVASIVE CARDIOL 2020;32(6):235-242. Epub 2020 May 20.

Key words: acute mitral regurgitation, outcomes, percutaneous leaflet repair

The management of patients with severe, decompensated mitral regurgitation (MR) remains challenging.¹ Owing to acute pulmonary congestion and left ventricular volume overload, many patients present in pulmonary edema with multiorgan dysfunction or shock.² Among patients presenting with MR complicated by cardiogenic shock, surgical mitral valve repair or replacement is associated with considerable morbidity and mortality.^3,4 Furthermore, over 50% of patients with MR complicating myocardial infarction are declined for surgical interventions due to prohibitive surgical risk.⁵ 

Percutaneous mitral valve leaflet repair with MitraClip implantation (Abbott Vascular) provides a novel therapeutic approach for inoperable patients.^6,7 The available evidence with percutaneous leaflet repair in this setting is limited to single-operator case reports with limited follow-up, which limits the generalizability of these observations. We report the clinical characteristics and procedural outcomes of consecutive patients with severe MR complicated by cardiogenic shock treated with MitraClip implantation at a high-volume center. 

Methods

Setting and patients. The study was conducted at Abbott Northwestern’s Heart Hospital, a tertiary 256-bed facility in Minneapolis, Minnesota that is affiliated with the Minneapolis Heart Institute Foundation. The Center for Valve and Structural Heart Disease at the Minneapolis Heart Institute has performed over 500 MitraClip procedures to date. We retrospectively identified consecutive patients undergoing MitraClip implantation for severe MR complicated by cardiogenic shock at Abbott Northwestern Hospital from January 2010 to October 2019. Shock was defined as systolic blood pressure <90 mm Hg for ≥1 hour not responsive to fluid administration alone, thought to be secondary to cardiac dysfunction, and associated with signs of hypoperfusion or cardiac index ≤2.2 L/min/mm² and pulmonary capillary wedge pressure >18 mm Hg.⁸ Baseline clinical, laboratory, and procedural information was prospectively captured using standard Transcatheter Valve Therapy Registry data collection forms (version 2.0) by trained personnel.

Outcomes. The primary outcome of the study was 30-day survival free of significant (grade ≤2). We also report periprocedural changes in inotropic support requirements and 1-year mortality whenever available. 

Statistical analysis. Continuous variables are presented as mean ± standard deviation or as median (interquartile range [IQR]) when appropriate. Categorical variables are reported as frequencies and percentages. Statistical comparisons were not performed due to the manuscript being descriptive in nature with no formal comparison group. All descriptive statistical summaries were performed with Stata, version 15.1 (StataCorp). The study was approved by the institutional review board of Allina. Individual consent requirement was waived.

Results

A total of 322 patients underwent MitraClip implantation during the study period. Eleven of these patients (3.4% of MitraClip cases) with severe MR complicated by cardiogenic shock were included in this analysis. A description of baseline characteristics is presented in Table 1. The mean age of the patients was 74 ± 11 years and 54% were male. The Society of Thoracic Surgeons (STS) risk score for mitral valve replacement was 15% (IQR, 6.9%-39%). Nine of the 11 patients were transferred from outside hospitals. All patients were deemed inoperable by the heart team. Prior to the procedure, 6 patients (54%) had acute kidney injury or were on renal replacement therapy, 5 patients (45%) received hemodynamic support with an intra-aortic balloon pump, and 9 patients (82%) received inotropic support (dobutamine in 5 patients, dopamine in 2 patients, and nipride in 4 patients).

Baseline echocardiographic and procedural characteristics are presented in Table 2. The mechanism of MR was degenerative in 7 patients (63.6%) and functional in 4 patients (36.4%). Functional MR cases included 1 patient post myocardial infarction, 1 patient with acute decompensation of chronic ischemic heart disease, and 2 patients with end-stage non-ischemic cardiomyopathy. All patients underwent MitraClip implantation in A2-P2 location, with 4 patients (36%) receiving ≥1 clip. Postprocedure MR was graded ≤2 in 8 patients (72%). The median fluoroscopy time was 18.4 minutes (IQR, 10.9-22.5 minutes). The postprocedure mitral mean gradient was 4.5 mm Hg and no patient required conversion to open surgery. Changes in hemodynamic support after MitraClip implantation are presented in Table 3. 

At 30 days post procedure, 8 patients (72%) were alive, with residual MR grade ≤2 (Table 4). There were 3 deaths within 30 days, but only 1 was attributed to cardiac causes (cardiac amyloidosis). The 2 other deaths were related to gastrointestinal bleeding leading to acute renal failure, and hospital-associated pneumonia with encephalopathy and sepsis. 

At 1 year post procedure, vital status was available in 9 of the 11 patients (81%). Mortality rate was 66% (6 of the 9 patients with available data) at 1 year. Of the remaining 2 patients, 1 was alive but did not have the necessary amount of follow-up time and 1 could not be contacted (out of state referral). Two of the 3 deaths that occurred after hospital discharge were non-cardiac; 1 was related to sepsis from peritonitis after feeding tube dislodgment, 1 enrolled in hospice due to severe psychiatric illness, and 1 was undetermined. 

Discussion

There is a need for less-invasive treatment options for patients with severe MR complicated by cardiogenic shock and prohibitive surgical risk. We report a case series of 11 such patients successfully treated with MitraClip implantation at a high-volume referral center. Most of the patients included were on inotropic or mechanical circulatory support prior to the procedure, with multiple comorbidities and advanced age. Despite these adverse characteristics, percutaneous leaflet repair with MitraClip was feasible in all patients, with 72% still alive with MR grade ≤2 at 30 days. Additionally, there was a significant de-escalation of inotropic support after MitraClip. 

Outcomes for operative candidates with acute severe MR have been previously reported in the surgical literature.⁹ At 30 days, mitral valve surgery was associated with a 22.5% mortality rate in a much younger cohort of patients (mean age, 62 years) with various mitral valve disease etiologies (degenerative MR, 26%; acute endocarditis, 28%; and post myocardial infarction, 45%).⁹ The majority of these patients underwent mitral valve replacement surgery (73%) and not mitral valve repair (27%). More relevant to our study is the proportion of patients who cannot undergo surgery due to prohibitive surgical risk. In the SHOCK (SHould we use emergently revascularize Occluded arteries in Cardiogenic shocK?) trial registry, fewer than half of patients (43%) with severe MR post myocardial infarction underwent surgery. Patients not offered surgery had larger myocardial infarctions and worse left ventricular function, which is indicative of treatment bias.⁵ Despite this selection bias, the group offered surgery had a 40% in-hospital mortality,⁵ which highlights the need for alternative treatments. 

Percutaneous leaflet repair with MitraClip is currently FDA approved for patients with degenerative MR, prohibitive surgical risk, and favorable anatomy, as well as in selected patients with severe functional MR in the setting of advanced heart failure symptoms despite optimal medical therapy.^10-12 The use of MitraClip for the treatment of acute MR complicated by cardiogenic shock is limited to case reports.^6,7,13-15 Our case series of 11 patients treated over a decade expands on these preliminary observations and could be used to inform the consent process. Adequately powered comparative trials of surgery and MitraClip are probably not feasible in this population, given declining rates of post-MI MR with reperfusion therapy, high level of technical expertise required, and other considerations.^16,17 Enhancements in mechanical circulatory support devices and percutaneous leaflet repair technology could expand the target population. The recent addition of the fourth-generation MitraClip device with wider clip arms, independently controlled grippers, and continuous left atrial pressure monitoring may facilitate leaflet grasping and further improve outcomes of these high-risk patients. 

Study limitations. Our study has limitations common to single-center, observational, retrospective cohort studies. These include selection bias, small sample size, and lack of a surgical control group, all of which limit the external validity. All operators in our study have performed more than 50 MitraClip implants, a threshold associated with improved clinical outcomes and less risk of complications.¹⁸ Caution is warranted when extrapolating these results to low-volume operators. 

Conclusion

Percutaneous leaflet repair with MitraClip is feasible in inoperable patients with acute MR complicated by cardiogenic shock and is associated with acceptable 30-day survival rates and MR reduction. 

From the Valve Science Center, Minneapolis Heart Institute Foundation at Abbott Northwestern Hospital, Minneapolis, Minnesota.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Bae reports personal fees from Abbott Vascular. Dr Cavalcante reports personal fees and grant support from Abbott Structural. Dr Gössl report personal fees from Abbott Vascular. Dr Garcia reports personal fees and grant support from Abbott Vascular. Dr Sorajja reports personal fees from Abbott Structural, Medtronic, Boston Scientific, Edwards Lifesciences, Admedus, Gore, and Teleflex. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted November 26, 2019, provisional acceptance given December 2, 2019, final version accepted December 6, 2019.

Address for correspondence: Santiago Garcia, MD, Minneapolis Heart Institute at Abbott Northwestern Hospital, 800 East 28th Street, Minneapolis, MN 55407.Email: santiagogarcia@me.com

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