A 68-year-old female with a cardiac history shows crackles bilaterally. What should you suspect?

In the context of a 68-year-old female with a cardiac history who presents with crackles bilaterally upon auscultation, the most appropriate suspicion is congestive heart failure (CHF).

CHF is a condition where the heart's ability to pump blood is impaired, leading to increased pressures within the heart and blood vessels. This can result in fluid backing up into the lungs, which causes pulmonary congestion. The presence of crackles, often described as "rales," is a classic sign of this fluid buildup in the alveoli of the lungs.

Given the patient’s age and cardiac history, it is reasonable to connect these factors to a potential exacerbation of heart failure. Simple pulmonary conditions such as chronic obstructive pulmonary disease (COPD) or asthma typically come with a different set of symptoms and are often associated with wheezing rather than crackles. Hypertension, while a risk factor for heart disease, does not directly correlate with the pulmonary symptoms observed here.

Therefore, based on the patient's symptoms and medical history, CHF stands out as the most likely condition leading to the observed clinical findings.