Ask The Doctors: December 2018
Q: I have heart failure and a severely leaking mitral valve. I am not a candidate for valve surgery, but I've heard about MitraClip. Is this an option for me?
A: An enlarging left ventricle caused by heart failure can strain the muscles and cords connected to the mitral valve, distorting the leaflets and preventing them from closing tightly between beats. When this happens, blood flows backwards into the left atrium, further overloading the heart. The condition, called mitral regurgitation (MR), increases the risk of hospitalization, poor quality of life and death from heart failure. Surgery in these patients is often very risky and may not be beneficial.
MitraClip is a device used to repair a mitral valve in a minimally invasive procedure. The device is introduced into the heart through a catheter and clipped to the underside of the valve leaflets, tightening the valve by forming two smaller openings.
Two recent trials comparing MitraClip to medical therapy in nonsurgical candidates with heart failure and severe MR reached very different results. The MITRA-FR trial, conducted in 304 patients over 12 months, found no difference in death or heart failure hospitalizations between the two approaches. In the COAPT trial, conducted in 614 patients over 24 months, MitraClip was associated with 47 percent fewer hospitalizations and 38 percent fewer deaths. The difference in results is likely due to the more stringent criteria used to define severe MR, less left-ventricular dilatation and better efforts to ensure appropriate medication use in COAPT. Although these subjects represent only about 10 percent of all heart-failure patients, this is a group in whom medical treatment is often ineffective. Therefore, there is good reason to be enthusiastic about these results.
A cautionary note is the importance of having new procedures such as this performed by experienced physicians in high-volume institutions.
Q: I am familiar with the CHA2DS2-VASc score for using anticoagulants to prevent a stroke. Can you explain how the HAS-BLED score differs?
A: These tools work together to help physicians make an informed decision about using oral anticoagulation (OAC). A CHA2DS2-VASc score is used to estimate stroke risk in individuals with atrial fibrillation. It assigns a score of 0 to 9 based on age, gender and history of heart failure, diabetes, stroke/TIA or vascular disease. A score of 0 is considered low risk, 1 is intermediate risk and 2 or more is high risk. A 70-year-old man with diabetes, prior stroke and hypertension would have a score of 5, which corresponds to a 6.7 percent yearly risk of stroke.
Generally, OAC is recommended for anyone with a score of 2 or higher and may be considered for a score of 1. Integral to this decision is the assessment of bleeding risk. The HAS-BLED score estimates the annual risk of major bleeding using hypertension, abnormal liver or kidney function, history of stroke, history of or predisposition to bleeding, labile INR indicating easy bleeding, elderly age, drugs (medications) taken concurrently and amount of alcohol used. A score of 3 or more indicates high risk for bleeding. Our 70-year-old man would have a score of 4, or a yearly bleeding risk of up to 8.9 percent. This would not be an absolute contradindication to OAC, since is stroke is more concerning than a bleeding event in most patients. HAS-BLED highlights patients in whom caution with OAC is warranted and helps identify and correct modifiable bleeding risk factors to improve the safety of OAC. These tools help in the decision to use OAC, which requires continuous re-evaluation of the risk of stroke versus that of bleeding.