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Ask Stanford Med: Answers to your questions about heart health and cardiovascular research

As the leading cause of death among both men and women worldwide, cardiovascular disease is a health concern that's near and dear to all our hearts. Earlier this month, we asked interventional cardiologist William Fearon, MD, to respond to questions about heart health and cardiovascular research in honor of American Heart Month. Below he answers a selection of questions submitted via our @SUMedicine Twitter feed and the Scope comments section.

As a reminder, these answers are meant to offer medical information, not medical advice. They're not meant to replace the evaluation and determination of your doctor, who will address your specific medical needs and can make a diagnosis and provide appropriate care.

Heather asks: I’ve experienced infrequent heart palpitations my whole life, mostly when lying down. But lately I’ve been experiencing them daily. At what point do heart palpitations signal a more serious condition?

Palpitations are a very common condition and in most cases benign. When palpitations become bothersome or frequent, most patients will seek medical attention. Vital signs such as low blood pressure or rapid heart rate can be a sign that the palpitations represent a more serious cardiac arrhythmia. Some simple tests such as an electrocardiogram, echocardiogram, blood tests and wearing a cardiac monitor can help to rule out any worrisome arrhythmia. Often changes in lifestyle, such as abstaining from caffeine products and getting more sleep, will relieve palpitations. Occasionally, medications are necessary.

Don Stanathan asks: I was diagnosed with dilated cardiomyopathy and later diagnosed with stage 4 lung cancer. I am stable and going strong, but I have had high blood pressure and high cholesterol for years and have been on medications for both. My question is how high can you allow your overall cholesterol level go before it overrides the cancer issues?

This is a difficult question to answer because it depends on weighing the risk of cancer against the risk of heart disease and balancing these risks with the risk of taking medications to prevent either of the above. One method for determining one’s risk from heart disease is the Framingham Risk Score, which can be accessed from any search engine on the web. After determining your risk of suffering a heart-related issue, you can discuss with your physicians the pros and cons of taking medications to reduce this risk.

Rebecca asks: A recent study shows that individuals with a common genetic variant for a certain type of cholesterol have a significantly (60 percent) greater risk of developing aortic calcifications. How might these findings lead to new therapeutic treatments or prevention options?

The relationship between lipid abnormalities and the development of aortic stenosis has been recognized for many years. This has prompted studies aimed at lowering cholesterol in an attempt to slow the progression of aortic stenosis. Unfortunately, these studies did not show any benefit to this strategy, perhaps because the population of patients studied and the method of lipid lowering used. The recent study to which you are referring found that a genetic variant in the lipoprotein(a) locus results in elevated levels of lipoprotein(a) and the development of aortic valve disease. With this new information, studies can be designed to include patients with this genetic variation and to treat them with medications specifically aimed at reducing lipoprotein(a). Whether this will result in prevention of aortic valve disease remains to be seen.

Lynn asks: I read that the transcatheter aortic valve replacement procedure carries a higher risk of stroke compared to open-heart surgery. Why is this? What are the other risks associated with this procedure?

The PARTNER 1A trial showed that patients at high risk for complications with open surgical aortic valve replacement had a major stroke rate of 3.8 percent when randomly assigned to the less invasive transcatheter aortic valve replacement compared to a rate of 2.1 percent when assigned to traditional surgical valve replacement. These rates were not statistically significantly different. However, when minor strokes and transient ischemic attacks were counted as well, the rate was 5.5 percent as compared to 2.4 percent, and this difference did become statistically significant. We are waiting for more studies in other patient populations and with different and newer transcatheter approaches to further define the risk of stroke with this new procedure.

The reason why the stroke risk may be greater with the transcatheter approach is likely related to deployment of the valve. First a balloon is used to open the valve (balloon valvuloplasty) and then the new valve, which is like a stent, is expanded with a balloon to deploy it within the old valve. Both of these aspects of the procedure can result in embolization of debris to the brain and a neurologic event. During traditional surgical valve replacement, the ascending aorta is clamped and the old valve is surgically removed. Before unclamping the aorta, embolized material can be removed in hopes of preventing neurologic events.

The main other risk associated with transcatheter aortic valve replacement is vascular complication due to the large catheter that is inserted typically through a vessel in the leg. As the technology improves, we expect both the stroke risk and the vascular complication risk to decline further.

Tom R. asks: Is there any potential for the transcatheter aortic valve replacement to be beneficial for low-risk or younger patients?

Yes, there is definitely potential for transcatheter aortic valve replacement to be beneficial in lower risk and younger groups of patients. However before this technique can be regularly applied to these patients, we need better valve devices that can be deployed in a more controlled fashion and easily repositioned. We also need devices that completely seal the old valve so that patients are not left with significant leak around the new valve. Finally, we need long-term data regarding the durability of transcatheter valves before using them in low risk, and particularly, in young patients.

Previously: Ask Stanford Med: Stanford interventional cardiologist taking questions on heart health, Guidewire technology improves heart patient care, New tool for heart disease saves both lives and money, Stanford researchers describe experimental treatment for deadly heart disease and Ask Stanford Med: Cardiologist Jennifer Tremmel responds to questions on women’s heart health
Photo by piX1966

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