FAILURE · Causes of heart failure exacerbation acronym

Heart failure is a clinical syndrome used to describe the inability of the heart to pump enough blood to meet the body’s demands. It affects millions of people around the world and is a leading cause of morbidity and mortality worldwide. There are a wide variety of conditions that can ultimately contribute to heart dysfunction, including coronary artery disease, hypertension, valvular heart disease, and many others—like alcohol and substance use, obesity, and diabetes mellitus.    

Heart failure can be due to either a failure of the heart to contract effectively, called systolic dysfunction, or failure to relax and fill properly, called diastolic dysfunction. Systolic dysfunction is commonly associated with a reduced left ventricular ejection fraction (EF), meaning the left ventricle is squeezing out less blood than it should with each heartbeat. This is why systolic heart failure is also known as heart failure with reduced ejection fraction (HF-rEF). With diastolic dysfunction, the heart muscle is squeezing hard enough but not filling properly, so despite a normal or preserved EF (>50%), the cardiac output is still inadequate. In both cases, blood can back up into the lungs and other body tissues, causing congestion or fluid build-up, which is why it is also known as congestive heart failure. 

Common symptoms of heart failure include fatigue, exercise intolerance, shortness of breath upon exertion, peripheral edema, and weight gain due to fluid retention. In most cases, heart failure follows a chronic clinical course where individuals remain stable for certain periods and then worsen rapidly due to an acute exacerbation of the symptoms. Even after stabilization, each exacerbation leads to a slight functional decline, leaving individuals with poorer exercise tolerance and worsening symptoms over time. 

The “F” in FAILURE stands for forgotten medications, including skipping doses, taking the wrong amount, or not following the prescribed treatment for heart failure. Currently, treatment for HF-rEF includes four pillars:  

• Beta-blockers (e.g., carvedilol, metoprolol) 

• Angiotensin receptor-neprilysin inhibitors (ARNI) (e.g., sacubitril/valsartan) 

• Mineralocorticoid receptor antagonists (MRA) (e.g., spironolactone, eplerenone), and 

• Sodium-glucose cotransporter 2 inhibitors (SGLT2I) (e.g., empagliflozin, canagliflozin).  

While it might seem like a lot of medications, adhering to quadruple therapy has proven to significantly reduce heart failure-related hospitalizations and cardiovascular deaths, even within the first 6 months of starting treatment. In fact, research suggests that this comprehensive treatment approach can extend life expectancy by approximately 6 to 8 years compared to conventional care or suboptimal therapy. 

The “I” in FAILURE means ischemia and infections. Here, ischemia refers to a myocardial infarction, where the coronary arteries supplying the heart become blocked and a segment of the myocardium, or heart muscle, loses its ability to contract properly. Because ischemia occurs suddenly, the body doesn’t have time to adapt to the rapid changes in heart function, resulting in a rapid worsening of the symptoms. If the blockage affects an artery supplying an extensive region of the heart, ischemia might be so severe that the heart is unable to function altogether, resulting in a cardiogenic shock.  

On the other hand, infections, such as those affecting the respiratory tract, can exacerbate chronic heart failure by increasing the metabolic and oxygen demands of the body, placing additional stress on the heart.  

The “L” in FAILURE means lifestyle, referring to changes in one’s diet and habits. Individuals with heart failure are typically advised to limit their sodium intake to 1,500-2,000 mg per day to help manage fluid retention and blood pressure. A common precipitating factor of heart failure is increased intake of sodium, which is commonly found in salty foods and condiments (e.g., soy sauce, ketchup, barbecue sauce, salad dressings), cured meats and cheeses, and highly processed foods.  

Likewise, individuals with heart failure may be recommended to limit their fluid intake as drinking too much fluid can overwhelm the heart's ability to pump and worsen fluid retention. Certain medications, such as non-steroidal anti-inflammatory drugs (NSAIDs), should also be avoided. Other recommendations include exercising regularly, avoiding smoking and alcohol consumption, managing stress levels, and maintaining a healthy weight to reduce strain on the heart. 

The “U” in FAILURE refers to upregulation of metabolic demands, which happens in conditions like hyperthyroidism or pregnancy. With hyperthyroidism, elevated thyroid hormones (T3 and T4) stimulate the heart, increasing heart rate and contractility. A faster heart rate reduces the filling time of the heart during diastole, which decreases the amount of blood pumped out to the rest of the body.  

In pregnancy, on the other hand, blood volume increases by up to 50%, leading to a higher cardiac output. In individuals with heart failure, the weakened heart function may not be able to handle the increased demand, worsening symptoms like fatigue, shortness of breath, and fluid retention.