What is the primary condition characterized by the heart's inability to maintain sufficient cardiac output?

The primary condition characterized by the heart's inability to maintain sufficient cardiac output is heart failure. Heart failure occurs when the heart cannot pump enough blood to meet the body's needs, leading to a range of symptoms including fatigue, shortness of breath, and fluid retention. This condition can arise from various underlying problems, such as coronary artery disease, high blood pressure, or previous heart attacks, which compromise the heart's function.

In contrast, arrhythmia refers to abnormal heart rhythms that can affect the heart's ability to pump effectively, but it is not specifically defined by an inability to maintain cardiac output. Myocardial infarction, or a heart attack, occurs when blood flow to a part of the heart is blocked, leading to damage that can ultimately contribute to heart failure. Hypertension, or high blood pressure, is a condition that can lead to heart failure over time as it places an increased workload on the heart. However, heart failure itself is the condition directly linked to the heart's inability to sustain adequate cardiac output.