These are a couple of Kaplan-Meier curves from a study of severe aortic stenosis patients1. First take a look at the time axis and be alarmed. In previous charts the time was in years. Here it is in months. So get your game face on and focus, this is a new ballgame. The curves show that as long as a patient doesn\'t have symptoms, they experience a 5% per year risk (top line). Pretty high, about the same as untreated severe mitral valve regurgitation and a higher risk than smoking. It means these asymptomatic patients have 10 years on average. That\'s the answer to the question, \"Doc, how long have I got?\": 10 years2. Before their stenosis is graded as \"severe\", the risk is lower and they have longer. Aortic stenosis may take 10, 20, 30 years to progress to severe.
But once symptoms develop and no surgery done, that\'s the lower curve. On average those folks only had 3 more years (50% gone at 3 years) after the onset of symptoms. The downhill slide is so fast, in fact, that about 4 or 5 percent of patients who scheduled surgery at this point died while waiting1,3. Oof.
The bottom line here is: if you have aortic stenosis, have a frank discussion with your doctors about the timing of surgery. Take a copy of \"The Guidelines\" (see my June 30 post) as a conversation prop and ask the doctor to go through the charts and recommendations. The choices will typically be between scheduling surgery once the grade is \"severe\" (when you start experiencing a 5% per year risk), or when symptoms develop - when you have a 15-20% risk per year4. In some cases surgery may not be an option. I am not a medical doctor, but in my view earlier surgery is better than later5. By a lot.
Keep the beat -- DVB6
Footnotes
1. DS Bach, D Siao, SE Girard, C Duvernoy, BD McCallister, Jr, SK Gualano, Evaluation of Patients With Severe Symptomatic Aortic Stenosis Who Do Not Undergo Aortic Valve Replacement: The Potential Role of Subjectively Overestimated Operative Risk, Circ Cardiovasc Qual Outcomes. 2009;2:533-539. Available as a pdf here.
2. Here\'s the calculation. How long do I have means what is my life expectancy, that is when have half of the people in my condition have died. At a loss rate of 5% per year it takes 10 years to lose 50%: 5% per year x 10 years = 50%.
3. DS Bach, N Cimino, Unoperated Patients With Severe Aortic Stenosis, ournal of the American College of Cardiology Vol. 50, No. 20, 2007. This is an unrefereed correspondence, available here as a pdf.
4. Suppose you have just scheduled surgery for AVR (aortic valve replacement) because symptoms have developed. The surgery date is 3 months in the future, a quarter of a year. Since your mortality risk is as high as 20% per year and you are experiencing that risk for 1/4 of a year it stands to reason that there is a 5%-ish chance that you will die before your surgery date: 20% risk per year x (1/4) year = 5% risk. This pre-operative wait risk is bigger than your operative risk!
5. I\'d think that there is an opportunity here to significantly enhance overall survival by adopting a different way of scheduling AVR surgery that decreased the time between deciding surgery was needed and the surgery itself. This could save up to 5 patients per 100, which really matters if you are one of them! But my reading of these journal pages is that most folks are waiting months. It would pay off to jump at any chance to move AVR surgery up (that didn\'t add some other, bigger risk).
6. Debbie A asked for my take on aortic stenosis with and without surgery. This post is about what happens without surgery, I\'ll show the improvement in survival odds with surgery later on. The improvement is quite impressive, but not quite as good as for mitral valve repair. However, new valve-sparing surgery options and catheter-based valve replacement techniques are coming on line that keep getting better.
The solid line shows the survival curve for an age-matched reference population, normal people. They slowly die off as time goes on. Since the average age of the group was 64, their mortality rate was about 3% per year. The dashed curve shows the surgical patients\' survival curve. A couple of things to note. First there is a sharp drop of about 7% right at the beginning. This was the operative and near-operative risk back then, about 25 years ago. It is now much better, and in some centers has recently been zero over many hundreds of surgeries, so don\'t be scared off by that. Second, after the sharp drop the curve is parallel to the reference population curve. That means patients are dropping out at the same rate as the reference population, and that means that their life expectancy is the same as the reference population once they survive the surgery. This chart is the origin of the wisdom that successful surgery gives you back your life expectancy, on average.
That on average bit is interesting. Patients in the study who were asymptomatic and had healthy ejection fractions did significantly better than the reference population! Even after accounting for peri-operative (operative and near-operative) mortality. Wow. And remember, the perioperative mortality rate is now much lower. The authors did not venture to explain why the ongoing mortality risk is lower than average in this group, but one idea is that these folks learned a lot about heart health in the aftermath of their \"adventure\" and adopted heart-healthy practices. Whether it was by this manner or another, they reduced their overall mortality rates by about 30% compared to average. Talk about a bonus prize - available to those who bite the bullet and have surgery before symptoms arise.
Another aspect of on average is that the study group contained a large number of mitral valve replacements (214) compared to the number of repairs (195). We now know that repair is superior to replacement5, so current patients who undergo repair prior to the onset of symptoms have most excellent outcomes, especially if they have their surgery done at a center of excellence.
Now that\'s something to get excited about!
-- DVB
Footnotes
1. See the CDC page on smoking and mortality. Smokers live 14 years less on average than non-smokers and smoking-related economic costs exceed 150 billion dollars a year (data from 1995 to 1999), about two to three times the size of the US tobacco products market.
2. I bought this textbook when diagnosed. Pricey but incredibly broad, deep, and useful. Amazon page.
3. JF Aviernos, BJ Gersh, LI Melton et al, Natural history of asymptomatic mitral valve prolapse in the community, Circulation 106, 1355 (2002). PDF available here.
4. M Enriquez-Sarano, AJ Tajik, HV Schaff, TA Orszulak, KR Bailey and RL Frye, Echocardiographic prediction of survival after surgical correction of organic mitral regurgitation, Circulation 90, 830 (1994). PDF available here.
5. Robert R. Moss, Karin H. Humphries, Min Gao, Christopher R. Thompson, James G. Abel, Guy Fradet and Brad I. Munt, Outcome of Mitral Valve Repair or Replacement: A Comparison by Propensity Score Analysis, Circulation 108, II-90 - II-97 (2003). PDF available here. By now you are an old hand at understanding survival aka Kaplan-Meier curves. Here\'s the one from this paper with my annotation showing that repairs are superior to replacement (be aware however that a repair is not always possible). The advantage is significant and is thought to be because in a repair the tissues are left intact and this leads to long term heart health.

These are Kaplan-Meier curves for men\'s survival against all causes of death according to a 2009 study using half a million people. This is a real eye-opening study. First notice that the data are stratified according to BMI (a measure of under/overweight-ness), that\'s why there are multiple curves. The curves show the chance of reaching a given age for various BMI cohorts. Here\'s how to read the plot. At each year the height of a curve says what fraction of men in that curve\'s BMI cohort are still alive with that age. As time goes on, men die in each cohort and the curve drops to the right. For example, at age 60, 91 percent of the blue population of men (top curve) are still alive. Those are the guys who have optimum BMI, around 24 kg/m2. It\'s a just-right number, you don\'t want your BMI to be much larger or much smaller. Knowing your height and weight you can calculate your own BMI5 easily. Hey, mine\'s 23, not bad. What\'s considered obese? That would be BMI over 30. Now here\'s the eye-opening thing. Check out how many of the very most obese guys (BMI over 40) are still alive at age 60. It\'s only 76%. They are represented by the lowest curve, the one with little red circles. They are two and half times more likely to die by age 60as the guys with optimum BMI6. 60 is not even retirement age. Thanks very much for your Social Security contributions, sorry you don\'t get any back. BMI over 40? Only about a third as likely to hit 80. And only one fifteenth as likely to hit 90. Ouch. This is why the obesity epidemic is considered a public health crisis. For you ladies the situation is a little better, but you\'re nowhere near off the hook. As for skinny skinny, skinny folks - the chart doesn\'t show your curve, but according to the paper having a BMI of 17 is as bad as having a BMI of 37. That\'s between the bottom two curves, pretty ouch too7. This brings me pretty close to full circle from where I started. And looking at the length of this post it\'s about time. The life expectancies published by the government are population averages, they include obese people. Obesity rates are increasing. Why? Calorie-rich low cost foods are more available and there are more opportunities for sedentary lifestyles. Maybe for other reasons too. All else being equal, increasing obesity would be shortening the average lifespan. But nationwide, on average, we are living longer. Given that the obesity rate is already 30%8 it means the optimum BMI folks are gaining life expectancy way faster than the average of two or three months per year9. That\'s a club I want to be in! You too, I\'ll bet. Glad I got that wonky valve fixed. My darling, I\'m hoping we still have a long, long time together. stayin\' alive-- DVB Footnotes 1. Your tax dollars at work produce the US Life Tables, an annual publication by the CDC. 2. With the advent of DNA sequencing and related technologies, medical science is becoming an information science. As such it will become subject to a kind of Moore\'s law of exponential growth, like computer technology\'s rapid advancement. Only two factors of two are needed for the average life expectancy to reach the 1-for-1 inflection point. In the computer realm that amount of improvement only takes 3 or 4 years. 3. Average lifespan after diagnosis of severe mitral regurgitation is 5-10 years, give or take. Bah. Subject of a future post. 4. Kaplan, E. L.; Meier, P.: Nonparametric estimation from incomplete observations. J. Amer. Statist. Assn. 53:457–481, 1958. Available as a PDF here for the geekiest among us. 5. More of your tax dollars at work. Explore that site. Tools to live by. 6. Here\'s the math: 100%-91%=9% gone in the optimum BMI group (blue line/squares) vs 100%-76%=24% in the high BMI group (red dashed line/circles). Then the ratio 24% divided by 9% is about 2.5. 7. These curves say there is a clear correlation of lifespan on BMI, that very high and very low BMI are mortality risk indicators. The curves do not say that changing your BMI will alter your lifespan directly. To show that rigorously would require studying people who changed their BMI and looked at how that change affected their lifespans compared to people who didn\'t alter their BMI\'s. On the other hand, the simplest explanation for the data is that indeed BMI does directly affect lifespan, so a prudent approach would be to safely modify your BMI to be in the optimal range. Because of human biology, this is very difficult for some people to do, but as you can see has large potential payoff. 8. The Center for Disease Control\'s page on obesity in America includes a year-by-year animated map showing the spread of the obesity epidemic. 9. I haven\'t done the calculation or gathered up the right data to do it, but I\'d expect the cohort with BMI between roughly 20 and 30 to be extending lifespan faster than average while those below 20 or above 30 to be extending lifespan less than average. Obese people are probably living longer now than obese people used to, but the obesity epidemic means that non-obese people with longer life expectancies are becoming obese people with shorter life expectancies as they gain weight.

Frankly it\'s a hard read, end to end. Written by cardiologists for cardiologists so quite a slog. Here\'s how I approached it: picked out just the parts needed using the fantastic table of contents then used wikipedia to decode the secret society jargon. Ah, just like studying for college all over again! But its real value is as a conversation prop. Print it out and take it with you to your cardiologist, or have them dredge up their dog-eared copy. They\'ve read it and know it inside out. Ask them to take you to the right section and go through it with you while discussing your own valves. Make notes on it. Have them thoroughly explain the what\'s and the why\'s. Make sure you are satisfied that you understand. These are just guidelines and every patient is different. Every doctor is different. Sometimes the best thing to do might not be one of the guidelines, it might be a deviation from the guidelines. Like it might be new and not yet rolled in. But you deserve to know that the judgement behind the deviation is sound. Confident that it\'s backed up by evidence. And that\'s where my first cardiologist strayed. He strayed away from The Guidelines without convincing me it was sound. That\'s why I have a new cardiologist. The Guidelines are the distilled wisdom and knowledge from decades of heart valve medicine. Vast treasures were spent learning what\'s in the guidelines. Trials, errors, studies, science, engineering, art, careers and lives. Millions of patients, thousands of doctors. Each patient bearing a gift of experience and knowledge for the doctors. Each doctor bearing a gift of care and cure for the patients. Yin and Yang. All tied together into a book of goodness and life. Learn and live -- DVB Footnotes 1. I\'ve pointed out The Guidelines in a bunch of HVJers Guestpages. I\'d appreciate hearing from any who\'ve used them and what your experience was. 2. The American Heart Association requests that this document be cited as follows: Bonow RO, Carabello BA, Chatterjee K, de Leon AC Jr, Faxon DP, Freed MD, Gaasch WH, Lytle BW, Nishimura RA, O’Gara PT, O’Rourke RA, Otto CM, Shah PM, Shanewise JS. 2008 Focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Valvular Heart Disease). Circulation. 2008;118:e523–e661.

The heart is a well-honed organ. Hundreds of millions of years of natural selection have weeded out variations that are less than the fittest, so the blood\'s flow through the heart has minimal turbulence and minimal resistance. That\'s why the interval between the beats in a normal heart are pretty silent and the beats themselves are short and well defined. Turbulent flow is noisy, takes a while to decay, and gives rise to murmurs. Bad valves make turbulent flow, lots of it. Ergo, bad valves produce heart murmurs. And lucky for us, dangerous heart murmurs are easy to find using a stethoscope. Listen to the beat -- DVB Footnotes 1. Always an adventure to embed links in a blog since the \"away file\" could disappear. I found these sounds using the google search terms: heartbeat audio files murmur. Man, I love Google. The linked file is from the University of Washington Department of Medicine site, which provides a whole collection of sounds for various valve disorders. 2. From Debbal and Bereksi-Reguig, \"Frequency analysis of the heartbeat sounds\", Biomedical Soft Computing and Human Sciences, volume 13, page 85 (2008). PDF version available here.

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