A 56-year-old man was referred for evaluation of severity of mitral regurgitation (MR). Three years ago, he was diagnosed with moderate mitral valve regurgitation due to mitral valve prolapse during a regular follow-up for his stable coronary artery disease. During his last visit with the referring cardiologist, the MR appeared to have increased. At that time, the patient did not report any symptoms and claimed to regularly perform mountain hikes. A bicycle stress test was terminated because of dyspnea at 98% of the age/gender predicted work capacity. Stress echocardiography immediately after the stress test revealed a right ventricle to right atrium pressure gradient of 69 mmHg.
On examination, the patient did not show clinical signs of cardiopulmonary decompensation. His blood pressure was 128/72 mmHg, and his resting heart rate was 56 bpm. On auscultation, there was a 3/6 systolic murmur at the apex and the left parasternal border.
Movies 1-4
Transthoracic echocardiography revealed eccentric MR toward the aortic root (Movie 1). The left ventricular (LV) size and systolic function were within normal range (LV volume indexed to body size: 56 ml/m2, three-dimensional [3D] LV ejection fraction: 61%), and the left atrium size was in the upper normal range (34 ml/m2 by 3D echocardiography). However, 3D strain depicted a reduced LV global longitudinal strain of -16.6% (normal range -19.9 ± 3.1) (Movie 2). Detailed analyses of the MR are shown in Movies 3 and 4, including systolic reversal of pulmonary vein flow, quantification of MR, and 3D transesophageal echocardiography (TEE).
A coronary angiogram showed patent epicardial coronary arteries. The results of the right heart catheter were as follows:
Cardiac index = 1.7 l/min/m2
LV end diastolic pressure = 12 mmHg
Mean wedge pressure = 15 mmHg
V-wave = 18 mmHg
Mean pulmonary pressure = 17 mmHg
The kidney function and the level of N-terminal pro-B-type natriuretic peptide were normal.
Should this patient be referred for mitral valve surgery?
Show Answer
The correct answer is: E. Yes. This is severe, clinically relevant MR, and surgical mitral valve repair is indicated because the chance for successful repair is high.
The recently updated guidelines1 describe several measurements to quantify MR, including those demonstrated in our patient. If four or more are met, MR can be assumed severe. However, as illustrated in this case of eccentric severe MR, the measurements are sometimes conflicting, and additional testing is necessary. The proximal isovelocity surface area method is suggested to further quantify MR by estimating the effective regurgitant orifice area, the regurgitant volume, and the regurgitant fraction. However, this method is less accurate in patients with eccentric jets, and small measurement errors can translate into largely inaccurate results. In such cases, matching functional with anatomical findings is crucial, and further assessment using TEE or cardiac magnetic resonance imaging is indicated. 3D TEE is our preferred method because it not only helps assess mitral valve morphology and severity of regurgitation, but it also predicts the complexity of mitral valve repair.2 In this patient, 3D TEE depicted a flail lateral part of the broad segment (P2) of the posterior leaflet. Although some echocardiographic images suggest the presence of anterior leaflet prolapse, operative inspection suggested that the pathology was isolated to the P2 segment. Furthermore, 3D quantification of the vena contracta area confirmed the severe coaptation gap. Thus, this patient suffers from severe MR.
The next question is whether the patient is truly asymptomatic and early in the course of chronic primary MR. The normal level of N-terminal pro-B-type natriuretic peptide does not answer this question but rather mirrors the compensated state at rest. More worrisome are three other aspects. Despite being a physically active man, his work capacity during the exercise test was below 100% of the age/gender predicted capacity. In addition, the increase of the right ventricle to right atrium pressure gradient to 69 mmHg post-exercise caused by MR represents an exercise-induced pulmonary hypertension and is a predictor of worse outcome after surgery.3 Furthermore, strain imaging of LV function revealed reduced global longitudinal strain as a marker of subclinical LV impairment. A recent study has demonstrated that a work capacity <100% predicted and reduced global longitudinal strain are independent predictors of worse long-term (>10 year) outcome after successful mitral valve repair.4
This patient suffers from severe, clinically relevant MR stage C1 (asymptomatic severe MR with preserved LV ejection fraction) or D (if we do not consider him truly asymptomatic as discussed). According to the 2017 AHA/ACC Focused Update of the 2014 Guideline on the Management of Patients With Valvular Heart Disease,5 there is a Class IIa indication for surgery if we assume stage C1 in this patient, and a Class I indication if we consider him symptomatic.
As this case demonstrates, decision-making can be challenging because not all clinical or echocardiographic signs of severe MR are equally met. Some might argue that a watch-and-wait strategy can be followed in such a case. However, the exercise stress test discussed above, together with the mildly reduced longitudinal strain, demonstrates the delicate balance in this patient, suggesting a more aggressive treatment plan. This patient is at low risk for cardiac surgery, and the 3D TEE demonstrated limited valvular disease (single segment flail of the posterior leaflet without calcifications). In dedicated mitral valve centers, such a patient can be operated with low operative mortality (<1%), a >95% likelihood of successful repair, and an excellent long-term outcome,6 often using a minimally invasive approach. However, because repair rates differ largely among centers,7 the referring physician should get information of the repair rate of the center of choice before sending the patient for mitral valve surgery.
The MitraClip (Abbott Laboratories, Abbott Park, Illinois) procedure is a safe alternative to surgery for clearly symptomatic patients who are high-risk surgical candidates. Thus, it is not an option for the patient in this case.8
References
Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr 2017;30:303-71.
Biaggi P, Jedrzkiewicz S, Gruner C, et al. Quantification of mitral valve anatomy by three-dimensional transesophageal echocardiography in mitral valve prolapse predicts surgical anatomy and the complexity of mitral valve repair. J Am Soc Echocardiogr 2012;25:758-65.
Magne J, Donal E, Mahjoub H, et al. Impact of exercise pulmonary hypertension on postoperative outcome in primary mitral regurgitation. Heart 2015;101:391-6.
Mentias A, Naji P, Gillinov AM, et al. Strain Echocardiography and Functional Capacity in Asymptomatic Primary Mitral Regurgitation With Preserved Ejection Fraction. J Am Coll Cardiol 2016;68:1974-86.
Nishimura RA, Otto CM, Bonow RO, et al. 2017 AHA/ACC Focused Update of the 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol 2017;Mar 10:[Epub ahead of print].
David TE, Armstrong S, Ivanov J. Chordal replacement with polytetrafluoroethylene sutures for mitral valve repair: a 25-year experience. J Thorac Cardiovasc Surg 2013;145:1563-9.
Kilic A, Shah AS, Conte JV, Baumgartner WA, Yuh DD. Operative outcomes in mitral valve surgery: combined effect of surgeon and hospital volume in a population-based analysis. J Thorac Cardiovasc Surg 2013;146:638-46.
Feldman T, Kar S, Elmariah S, et al. Randomized Comparison of Percutaneous Repair and Surgery for Mitral Regurgitation: 5-Year Results of EVEREST II. J Am Coll Cardiol 2015;66:2844-54.
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