What is cardiac reserve?

From the Guidelines

Cardiac reserve refers to the ability of the heart to increase its output in response to physical activity or other stressors.

Definition and Mechanisms

• Cardiac reserve is often defined as the difference between the maximum cardiac output and the resting cardiac output [ 1 ].
• It is influenced by various factors, including heart rate reserve, stroke volume, and contractile function [ 1 ].
• Chronotropic incompetence, which is the failure to reach a target heart rate with exertion, can impair cardiac reserve [ 1 ].

Clinical Assessment

• Cardiac reserve can be assessed using various methods, including exercise stress testing, echocardiography, and cardiopulmonary exercise testing (CPX) [ 1 ].
• CPX can provide valuable information on cardiac function, including heart rate reserve, ventilatory threshold, and peak oxygen uptake [ 1 ].

Clinical Implications

• Impaired cardiac reserve is associated with various cardiovascular conditions, including heart failure, coronary artery disease, and cardiomyopathy [ 1 ].
• Assessing cardiac reserve can help guide exercise prescription, risk stratification, and management of patients with cardiovascular disease [ 1 ].

From the Research

Definition of Cardiac Reserve

• Cardiac reserve is defined as the difference between basal and maximal cardiac performance 2
• It represents the heart's ability to increase its output in response to physical activity or other stressors

Measurement of Cardiac Reserve

• Cardiac reserve can be measured non-invasively using techniques such as CO2 rebreathing 3
• Cardiac power output (CPOmax) at peak exercise is a significant indicator of cardiac reserve and correlates well with aerobic capacity and exercise duration 3
• Echocardiography, invasive hemodynamics, and Langendorff techniques can be used to assess systolic and diastolic reserves in preclinical models 4

Importance of Cardiac Reserve

• Cardiac reserve is a major determinant of exercise capacity in patients with heart failure 3, 5
• It is also a significant predictor of post-device survival in patients with mechanical circulatory support 2
• Cardiac reserve can be used as a marker for early detection of cancer treatment-related cardiac dysfunction (CTRCD) 6

Factors Affecting Cardiac Reserve

• Sex differences can affect the interpretation of cardiac reserve assessment, with differences in dose response to dobutamine and echocardiography parameters 4
• Cardiac reserve can be influenced by various factors, including cardiac function, exercise capacity, and therapeutic interventions 3, 5