Final answer:
The healthcare organization is using core measures as defined by the Joint Commission to collect performance data on care for heart attack, heart failure, and pneumonia.
Step-by-step explanation:
The performance measure set that the healthcare organization is using, according to the details provided, is core measures. Core measures are standardized sets of data hospitals collect to measure the quality of certain aspects of patient care. The Joint Commission designates these core measures for hospitals to track and report, which may include care for conditions such as heart attacks, heart failure, and pneumonia. Collecting and analyzing this data helps healthcare providers to improve the quality and safety of patient care.