 Hello, everyone. My name is Aidan Sharkey, and I'm an attending anesthesiologist at Beth Israel Deaconess Medical Center in Boston. And today we're going to be discussing ischemic mitral regurgitation using a case-based approach. I will be discussing four unique cases today, and I plan to go through the thought process and rationale behind decisions that were made during these cases. I have no conflicts or disclosures. For those who don't know me, prior to coming to Boston three years ago, I completed my cardiac fellowship in Toronto, and it is both an honor and a privilege to be asked to speak at this prestigious conference today. I'm also glad to see Bilal sharing this session today. Bilal and I are longtime friends from Ireland, so it is great to see him again, along with everyone else from Toronto General Hospital. So today we're going to be discussing ischemic mitral regurgitation. And my goal today is to give a brief background on this topic before going through our four cases. So when we think about ischemic mitral regurgitation, it is important to remember that this is not a leaflet problem, but instead an apparatus problem. Indeed, the valve leaflet and cordial structures can be thought of as innocent bystanders. And regurgitation is due to papillary muscle displacement, leaflet tethering, reduced closing forces, and annular dilatation. There are many controversies when it comes to ischemic mitral regurgitation, and significant research still needs to be done in this area. Some of the controversies relating to ischemic mitral regurgitation include, who should have an intervention? When should this intervention be done? What intervention should be done? And does this intervention have any survival benefit of these patients? The American College of Cardiology and American Heart Association have guidelines trying to answer some of these questions. And these guidelines state that intervention should be considered in patients undergoing coronary revascularization surgery with moderate to severe mitral regurgitation. Then comes the question as to what intervention should be undertaken in these patients at the time of surgery? Should these patients undergo mitral valve repair or mitral valve replacement therapy? This is a complex and important consideration for patients. And recent randomized trials have attempted to answer these specific questions. In this randomized controlled trial that looked at repair versus replacement in ischemic mitral regurgitation, the authors found no significant difference in left ventricular reverse remodeling or survival between patients who underwent mitral valve repair compared to those who underwent mitral valve replacement. In the two-year follow-up to this study, the authors found that mitral regurgitation recurred more frequently in the repair group, resulting in more heart failure related adverse events and cardiovascular admissions. However, the authors did note that on subgroup analysis that patients in the repair group who did not have recurrent mitral regurgitation had significantly reverse remodeling and an overall better quality of life. So given this, the real question should be, how can we carefully select patients who will benefit from mitral valve repair surgery? This is where we as cardiac anesthesiologists play an important role in the decision-making process. Transesophageal echocardiography and more specifically, three-dimensional transesophageal echocardiography plays an integral role in guiding therapy. The role of transesophageal echocardiography has expanded from a monitoring modality to a procedural adjuvant. The value of 3D echo is that it has the ability to assist us in navigating through complex decision-making with regards to mitral valve interventions and providing roadmap of mitral valve anatomy for possible repair. In our department, we perform a lot of mitral valve surgeries and in order to standardize our approach and be consistent with the information we deliver to our surgeons, we tend to follow an algorithmic approach when determining if a mitral valve is suitable for repair or if a replacement is a better option for the patients. We have recently published our approach and this is not meant to replace well-established guidelines that already exist on how to examine the mitral valve but merely to highlight how we approach a mitral valve for suitability for repair. This is our algorithm that we follow and we utilize on a day-to-day basis and I will be referencing this algorithm throughout the remainder of my talk. So moving on to our case-based discussion and when we encounter ischemic mitral regurgitation in the operating room, we can encounter itch emergently, acutely or incidentally. So our first case today, this is a 74-year-old gentleman who had a ST elevated MI. He presented hemodynamically unstable with an inferior infarct and had a intraaortic balloon pump inside him for hemodynamic support. After catamethalation, he was brought to the operating room for an emergent bypass surgery. On TE examination of this patient, we can see that there is a rupture of the posterior medial papillary muscle. More imaging in this patient clearly shows the rupture of papillary muscle and a flail anterior leaflet as a consequence of this. On 3D imaging of this patient, the mitral valve, we can see that the flail leaflet is in the left atrium and then with the color flow Doppler, we can see a posteriorly directed jet of severe mitral regurgitation. So clearly this patient needs a mitral valve intervention and looking at how we first approach mitral valve in our decision-making algorithm, it is our first step to exclude immediate contraindications to repair. Immediate contraindications that we consider preclude a possible repair include active and effective endocrinitis, mitral stenosis, significant mitral aneurocalcification and emergent surgery with ischemic papillary muscle rupture, where definitive procedure with minimal time on bypass is of the essence. Consequently, in this situation, we decided to proceed with bypass surgery and mitral valve replacement. Obviously a valve sparing procedure could not be performed. So the damage papillary muscle and cordae along with the leaflet were resected as seen in the specimen here. Moving on to our next case, this is a 68-year-old gentleman who presented with shortness of breath and chest pain or exertion. His background history was of known ischemic heart disease along with hypertension and hyperlipidemia. He proceeded to have a coronary angiogram to investigate his symptoms. I was subsequently found to have severe coronary artery disease as seen in the representative diagram. Of note, a recent preoperative trans thoracic echo demonstrated mild mitral regurgitation. He presented to the operating room for bypass surgery and underwent uneventful induction of general anesthesia with very stable hemodynamics. We performed our baseline trans-sophageal echocardiography examination which showed moderate LV dysfunction with global hypokinesis and also an achinetic apex. We then proceeded to our examination of the mitral valve where we demonstrated no more than mild mitral regurgitation which was as advertised in this patient. Post-wave Doppler of the left upper pulmonary vein showed mild blunting and the venic contractor was consistent with mild regurgitation. So our assessment of this patient was he had moderate LV dysfunction with mild mitral regurgitation. As the surgery progressed and the memory was being taken down, we noticed that there were some hemodynamic changes with the patient. Specifically, the patient had become a bit more hypertensive, tachycardic and also the PA pressures began to rise. We had another look with the trans-sophageal echo and what we noticed was that there was now a significantly worse LV dysfunction with almost complete achinesis of the inferior wall. We reexamined the mitral valve and at this stage we noticed that the mitral regurgitation was considerably worse with a large central jet of mitral regurgitation. Further assessment of the mitral regurgitation showed that the regurgitation was at least of moderate, if not severe intensity, which was a big difference from the baseline in this patient. We also noticed that co-optation of the mitral valve leaflets was not as good as baseline in this patient. We felt at the time that this was all ischemia related and as we were not ready at this stage to go on to bypass, we just started to start some anti-ischemic therapy with nitroglycerin. After we started the nitroglycerin therapy, we saw an immediate improvement in LV contractility and also an improvement in the co-optation of the mitral valve leaflets. Again, we reexamined the mitral regurgitation after commencement of the nitroglycerin and what we noticed was that the regurgitation had come back down to mild in nature. Just looking at the regurgitation pre and post commencement of the nitroglycerin, we can see a considerable improvement in the degree of mitral regurgitation in this patient. So at this stage, we were left with the predicament of what should we do with this patient? Should we ignore the mitral regurgitation and proceed with the cabbage as previously planned? Should we perform a coronary artery bypass with mitral valve repair? Or should we perform a coronary artery bypass with mitral valve replacement? So examining this patient's mitral valve apparatus further and looking at some valve geometry, we can see that this is not exactly a normal valve as there is some evidence of remodeling. However, there did seem to be a good leaflet co-optation when the patient was not ischemic, as seen here with a good anatomical or co-optation reserve between the mitral valve leaflets. So given all this data, the decision was made to proceed with the cabbage surgery alone and we did not intervene in the mitral valve and the patient did very well coming off bypass and in the postoperative period. So moving on to our next case, this is a 72-year-old female who was found to have severe three-vessel coronary artery disease on investigation for increasing shortness of breath and chest tightness. It was also noted that she had moderate to severe mitral regurgitation in the preoperative transtheracic echo. On examination of the mitral valve, we can clearly see that there is significant dysfunction and there is a large jet of central mitral regurgitation that is at least moderate to severe in intensity. We then proceeded to perform some 3D imaging of the mitral valve with color flow Doppler and this confirmed our findings of a significant mitral regurgitation jet which was central at the A2P2 commissures. So looking at our decision-making algorithm, there is no immediate contraindications to repair this patient and we have clearly identified the presence of dysfunction in this patient. So with that, our next step is to quantify the degree of dysfunction and for this, our primary method is the venocontractor method. Despite many pitfalls with this method, we find it to be a very quick, reproducible and good method to distinguish mild and severe regurgitation. In patients with moderate mitral regurgitation, this method should not be used alone due to their propensity to underestimate the degree of mitral regurgitation. In our specific patients, we graded the regurgitation as severe based on the venocontractor and the presence of flow reversal in the left upper pulmonary vein. So now that we have quantified the degree of dysfunction, our decision-making algorithm is to identify the mechanism of dysfunction and to do this, we follow the carpentia classification system. In this patient, we can clearly see that there is leaflet tethering with an annulus that is not dilated. So given this, we classify this as carpentia type 3B dysfunction. Next, it is our routine practice to establish the pathophysiology of dysfunction and at this instance, it is ischemia related. When we quantify valve geometry and identify indices of mitral valve apparatus remodeling. When we quantify valve geometry, there are simple-to-use artificial intelligence software available for us to use that give us an abundance of information such as highlighted in these images. These software packages offer quick analysis of the geometric changes of the mitral valve that occurred throughout the cardiac cycle. We can also perform basic geometric analysis using manual calipers such as tented height, tented area, P3 leaflet retracted angle, along with indices that predict the occurrence of some post-mitral valve repair, such as the ALPL ratio, CSEF distance, and mitral aortic angle. It is important to measure all these geometric indices as these all play a role in the final decision as to whether we should repair or replace the patient's mitral valve. In patients who have predictors of repair failure such as dilated ventricles, significant leaflet retraction as evidenced by increasing tented height, tented area, and P3 leaflet retraction greater than 29 degrees, then these patients should proceed to mitral valve replacement as opposed to repair due to the risk of repair failure. Certainly back to our patients, we can see that there is significant evidence of remodeling as seen by an increased tented height, an increased tented area, and also the P3 leaflet retraction angle that was measured at 59 degrees. Also in this patient, very importantly, there was evidence of a basal aneurysm, and a basal aneurysm is highly associated with repair failure. So given all this information that we have collected, we decided that the best decision for this patient was to proceed with bypass surgery and a mitral valve replacement in this patient. Moving on to our final case, this is a 62-year-old male patient who was having unstable angina and was found to have pre-versal coronary artery disease as seen on the angio. A transterrastic echo that was done pre-operatively showed moderate to severe mitral regurgitation. He presented to the operating room for his cardiary bypass surgery, and after an uneventful induction of general anesthesia, we performed our transesophageal echocardiography examination of the mitral valve. And our assessment of the mitral regurgitation was that it was mild to moderate in severity. Given this patient had documented moderate to severe mitral regurgitation on his pre-operative transterrastic echo, we decided we would augment his physiology with an increase in pre- and afterload. And after doing this, we noticed a definite increase in the severity of mitral regurgitation. This concept of matching awake state hemodynamics when assessing the degree of mitral regurgitation has been shown to more accurately assess the degree of regurgitation in patients under general anesthesia with the caveat of sometimes, in fact, overestimating the severity. So it must be used with some degree of caution. We then proceeded to perform some three-dimensional analysis of the mitral valve. And this did not reveal any structural abnormality of the valvular leaflets except for some leaflet tethering when the valve was viewed from the left ventricular aspect. When we add a color flow dopper to our three-dimensional images, we can see a significant jet of central mitral regurgitation. And using some of the new rendering software such as the class view, we can really appreciate the broad base jet of this mitral regurgitation. So again, when we go through our decision-making algorithm, we can see in this patient there was no immediate contraindications to repair. But we've clearly identified the presence of dysfunction. Our next step is to quantify the dysfunction. And as I stated previously, we routinely use the vena-contractor method. As I previously said, this is a good method that is quick, easy, reproducible, and easy to use. However, it also has the pitfalls of not being very accurate in patients with ischemic mitral regurgitation, where the effective regurgent are of this area is non-circular in nature and more elliptical in nature. Consequently, using the vena-contractor method will often underestimate the degree of mitral regurgitation. As we can see in this case here, where we measured the 2D vena-contractor which would put this patient in the moderate range. In cases such as this, we will routinely measure 3D vena-contractor, which is a more accurate measure of the effective regurgent-arvors area of the regurgent and jet in patients with ischemic mitral regurgitation. In this particular patient's instance, we measured the 3D vena-contractor to be 0.41 cm2, which automatically puts this patient in the severe range and most definitely warrants an intervention for the mitral valve in this patient. So again, going back to our decision-making algorithm, our next step would be to quantify the mechanism of dysfunction according to Carpentier's classification system. With our patient, we can see that there is no excessive leaflet motion. The alias was not dilated. However, there was evidence of leaflet tethering. So again, we classify this as a type 3B dysfunction. And in terms of establishing the pathophysiology of dysfunction, in this patient, it is ischemic in nature. So automatically, our next step is to quantify valve geometry and identify indices of mitral valve remodeling. As stated previously, we routinely measure tenting height and tenting area as markers of remodeling. And these can be measured in two-dimensional reviews. Or we typically do all our measurements with multi-planar reconstruction. The value of using multi-planar reconstruction is that we can be very precise in the measurements we make and where we make them. We routinely measure the P3 leaflet retraction in patients such as this. And using multi-planar reconstruction allows us to easily confirm that it is actually the P3 scallop that we are measuring, which we cannot traditionally do in 2D echocardiography. We also routinely assess for predictors of SAM after mitral valve repair. And we again do this using multi-planar reconstruction where we measure the AL to PL ratio, the CSEF distance, and mitral aortic angle. Putting all this together when deciding if this particular patient is suitable for mitral valve repair or replacement. We can see that while this patient has evidence of remodeling, there are no geometric indices indicating that he is at a high risk for repair failure. The patient's tending height, tending area, and P3 leaflet retraction angle and LV dimensions all point towards a durable repair for this patient. Also, there were no high risk indicators of post repair SAM in this patient. And as a result of all these, this information that we collected, we decided for this patient that we would perform a mitral valve repair as part of his bypass surgery. And again, this patient did very well in his post-operative course. So in conclusion, a scheme of mitral regurgitation is a complex problem of the mitral valve apparatus. An intervention should be considered in its select patients undergoing coronary artery bypass surgery. It is important to note however that repair is not an operation for everybody. And that 3D echocardiography has an integral role in identifying patients who may benefit from repair. Finally, looking at potential future studies in this area, we at BIDMC are very interested in trying to figure out if we can somehow identify patients who might be at risk of future regurgitation. And if early intervention might be an option in these patients at the time of their bypass surgery. Just because a valve is non-regurgitant does not automatically imply that it has normal function. And this idea plays into the concept of mitral valve co-optation reserve and the risk of mitral regurgitation. This co-optation reserve acts to sustain ischemia related remodeling and prevent development of mitral regurgitation. And based on the available reserve, non-regurgitant mitral valves could vary in their risk of developing systolic incompetence. And identifying patients at risk could mean prophylactic intervention before overt systolic malco-optation of the mitral valve leaflets resulting in mitral regurgitation.