Heart Failure: An Avoidable Endgame
Misconceptions about what heart failure truly is abound. Heart failure is closely related to, often confused with, and sometimes overlapping with a series of confusing acronyms and terms that delineate related conditions, including CVD, CHD, CAD, atherosclerosis, atrial fibrillation or “ischemic” anything; but heart failure can even be mistaken for an acute medical crisis more resembling MI, or “heart attack.” Understanding exactly what heart failure is and being able to spot the symptoms is important both for your own health as you age and for the health of those close to you. You may find yourself currently or one day having to manage care for a loved one who may not be taking care of themselves as well as typical readers of Running & FitNews strive to do.
What is heart failure?
Heart failure is the name for a chronic health condition in which the heart isn't pumping efficiently enough to meet the body's need for blood.
When the body first detects that it's not getting an adequate blood supply, it tries to compensate. Stress hormones rise, pushing the heart to beat faster and harder. Blood vessels narrow in an effort to keep blood pressure stable. To keep blood flowing to the heart and brain, the body diverts blood away from less important tissues. The body also retains sodium and fluid in an attempt to supplement the volume of circulating blood.
Heart failure causes two major problems for the body:
- Insufficient oxygen is delivered to tissues and organs
- Excess fluid accumulates in the tissues and lungs
Lack of oxygen can lead to fatigue and mental confusion, while fluid buildup can cause weight gain and swelling in the feet and ankles. If you're unfamiliar with heart failure, you could easily interpret these as isolated symptoms. People often mistakenly attribute the early signs of heart failure to being out of shape, being overweight or just getting old. Adding to the confusion is the fact that the symptoms can wax and wane over the course of the illness.
When heart failure mainly affects the left side of the heart, blood backs up into the lungs, causing shortness of breath and coughing. When mainly the right side is affected, blood backs up into the veins and builds up in body tissues, often leading to swelling in the legs.
Dangerous, but chronic
Perhaps due to the immediate and urgent-sounding nature of its name, many people confuse heart failure with myocardial infarction or cardiac arrest.
In contrast to the above symptoms and physical effects, myocardial infarction is an acute or sudden drop in blood flow to the heart, within a wide range of severity. With MI the heart can fail, per se, or become extremely erratic. MI is usually caused by coronary artery disease (CAD), which is not diagnostically distinct from coronary heart disease (CHD), adding to the confusion.
Note that an MI, caused by CHD, may cause heart failure: the chronic condition is helped along by the acute circumstance of lack of blood flow, leading to permanently damaged heart tissue that fails in the chronic, compromised or underperforming sense.
More immediately, an MI can also lead to cardiac arrest—that is, when the heart fails to contract and blood stops circulating in the body—but it doesn’t always.
Understanding heart failure, CHD, arteriosclerosis, A-fib and ischemia
In most instances, ischemic heart disease, i.e., CAD or CHD, is a result or consequence of arteriosclerosis (a hardening of the arteries that compromises their ability to expand when a greater rate of blood flow to the organs is called for) and atherosclerosis (the buildup of fatty deposits within the arteries that narrows them). These two terms are common types of cardiovascular disease (CVD), a general term for conditions that involve narrowed or blocked blood vessels. When the coronary artery becomes affected by arteriosclerosis or atherosclerosis, it may become occluded, causing impaired blood supply to the myocardium (heart muscle). Ischemic heart disease is frequently a forerunner of atrial fibrillation (A-fib), which is an erratic heartbeat signaling that the heart muscle is stressed and working inefficiently or beyond its capability.
The terms “ischemia” and "ischemic" refer to a specific form of cardiomyopathy, or heart disease. “Heart disease” is a catchall phrase for any measurable deterioration of the heart muscle’s ability to contract, leading to, by definition, the chronic compromised-performance state of the myocardium known as heart failure. Ischemia is a restriction in blood supply to tissues, causing a shortage of oxygen (and glucose) needed for cellular metabolism, which keeps tissue alive.
Ischemia can be thought of as essentially a delivery problem; the blood vessels for whatever reason are unable to supply blood to the organs that are said to suffer from ischemia. This includes the heart, which circulates oxygenated blood to itself in a loop that sends blood to the lungs and back.
A summary of heart problems: cause and effect
Ischemia is a subcategory of cardiomyopathy,
or any disease of the heart muscle.
CVD is a general term for when blood can’t
flow optimally through arteries and veins.
CVD → ischemic heart disease (IHD)
IHD = CHD = CAD
CAD → A-fib
CAD → MI or heart failure
MI → heart failure
Heart failure → oxygen deficit to
tissues and fluid buildup in them
Pulmonary edema refers to fluid
buildup in the lungs specifically.
→ leads to
= is the same as
Whether or not CHD causes an MI along the way, CHD has a huge causal role in heart failure. What else can cause heart failure, and what can prevent it? These answers are not entirely surprising, though there is one underlooked group of suspects, and one underlooked preventive measure, to consider.
Heart failure is associated with a highly complex drug regimen, ironically increasing the risk of heart failure exacerbation either by direct myocardial toxicity, multiple drug interactions or both.
The American Heart Association recently published in Circulation a comprehensive list of prescription drugs that may lead to or worsen heart failure.
Some of the drugs that may exacerbate existing myocardial dysfunction include nonsteroidal anti-inflammatory drugs, COX-2 inhibitors, metformin, dronedarone, verapamil, tricyclic antidepressants and itraconazole. Some that could cause direct myocardial toxicity include appetite suppressants, clozapine, docetaxel and stimulants. You can view the full list in pdf form here.
Role of exercise
It’s widely known that exercise helps prevent CHD, and therefore heart failure. A new meta-analysis in BMJ sorts out just how exercise helps stave off five major diseases.
The first main tier of benefits were found at a MET level of around 3,600 minutes per week, the equivalent of about 20 minutes of running or 25 to 30 minutes of bicycling seven days a week. And while health gains beyond that level of activity were subject to a kind of diminishing returns phenomenon, the paper saw gains really top out at much higher: 8,000 MET minutes per week.
The World Health Organization recommends getting in no less than 600 MET minutes per week, which translates to about 150 minutes if the intensity is moderate, or 75 minutes at a vigorous intensity. The researchers found that exceeding this significantly had a big reductive impact on disease risk. All percentages are derived by comparing the WHO’s 600-MET low threshold to 8,000 MET minutes per week:
- Diabetes: 28% lower risk
- Ischemic stroke: 26% lower risk
- Ischemic heart disease: 25% lower risk
- Colon cancer: 21% lower risk
- Breast cancer: 14% lower risk
Role of whole grains
A lesser obvious weapon in the arsenal against ischemia, heart disease and heart failure comes to us through the diet. Another large meta-analysis in BMJ finds that the health risk reduction to be found through increased whole grain consumption is even better than previously thought.
An increase in whole grain consumption of 90 grams per day yielded significant health gains. This is the equivalent of just two slices of whole grain bread and one bowl of whole grain cereal, or one and a half pieces of pita bread made from whole grains, added to the diet daily. Reductions in risk were observed up to an intake of seven and a half servings per day for most outcomes.
An increase in whole grain intake of just three more servings per day was associated with:
- CHD: 16% lower risk
- Cancer: 15% lower risk
- CVD: 13% lower risk
The relative risks of mortality from the following were also significantly lowered: total cancer, respiratory disease, diabetes, infectious diseases, nervous system disease, and all non-cardiovascular, non-cancer causes.
Intakes of whole grain bread, whole grain breakfast cereals and added bran all lowered health risk, whereas intake of refined grains and white rice did not. One mechanism that is likely in play here is that the high fiber content of whole grain foods can lead to better glycemic control. The authors agree with current dietary recommendations that call upon us to increase intake of whole grains and as much as possible choose them over refined grains. So should we all agree.