Heart failure is caused by diseases or other factors that affect the pumping ability of the heart, specifically the left lower chamber (left ventricle). When the heart cannot pump well, it is called systolic heart failure. Things that affect how the heart pumps include:

• Coronary artery disease (CAD) and heart attack (most common causes).
• Damage from poorly controlled high blood pressure or diabetes.
• Cardiomyopathy, alcoholic cardiomyopathy, or infection or inflammation of the heart muscle (such as myocarditis).
• Illegal drugs (such as a stimulant, like cocaine).
• Disease of the sac surrounding the heart (pericardial disease).
• Heart disease that is present from birth (congenital heart disease).
• Heart valve disease.
• Fast, slow, or irregular heart rhythms (arrhythmias).
• Aging. As you age, your heart muscle tends to stiffen, which can prevent your heart from filling properly with blood.
• A rare kind of heart failure called postpartum heart failure. This can happen late in the pregnancy or within the first 5 months after delivery.

When the left ventricle cannot fill properly, it is called diastolic heart failure. High blood pressure, coronary artery disease, and heart valve problems can cause diastolic heart failure.

Specific triggers may suddenly make heart failure worse and may sometimes cause life-threatening conditions such as pulmonary edema or cardiogenic shock.