Key result
In healthy Landrace pigs, dobutamine stress significantly increased external myocardial power from 1.3 to 2.3 W/m2 (p=0.005), while verapamil-induced ischemia decreased it to 0.8 W/m2 (p=0.005).
Why the study?
Measuring myocardial efficiency typically requires invasive catheterization and ionizing radiation, prompting the need for non-invasive assessment during pharmacological stress and ischemia.
Does non-invasive CMR accurately quantify changes in myocardial power and efficiency during dobutamine stress and verapamil-induced ischemia in healthy pigs?
Does non-invasive CMR accurately quantify changes in myocardial power and efficiency during dobutamine stress and verapamil-induced ischemia in healthy pigs?
Non-invasive CMR can successfully quantify myocardial power and efficiency changes under stress and ischemic conditions, offering a potential radiation-free alternative to invasive catheterization for evaluating myocardial energetics.
Hypothesis-generating for CMR myocardial power assessment in porcine stress/ischemia; leaves open human translation and validation.
Background: Myocardial efficiency should be maintained stable under light-to-moderate stress conditions, but ischemia puts the myocardium at risk for impaired functionality. Additionally, the measurement of such efficiency typically requires invasive heart catheterization and exposure to ionizing radiation. In this work, we aimed to non-invasively assess myocardial power and the resulting efficiency during pharmacological stress testing and ischemia induction. Methods: In a cohort of n = 10 healthy Landrace pigs, dobutamine stress testing was performed, followed by verapamil-induced ischemia alongside cardiac magnetic resonance (CMR) imaging. External myocardial power, internal myocardial power, and myocardial efficiency were assessed non-invasively using geometrical and functional parameters from CMR volumetric as well as blood flow and pressure measurements. Results: External myocardial power significantly increased under dobutamine stress [2.3 (1.6–3.1) W/m 2 vs. 1.3 (1.1–1.6) W/m 2 , p = 0.005] and significantly decreased under verapamil-induced ischemia [0.8 (0.5–0.9) W/m 2 , p = 0.005]. Internal myocardial power [baseline: 5.9 (4.6–8.5) W/m 2 ] was not affected by dobutamine [7.5 (6.9–9.0) W/m 2 , p = 0.241] nor verapamil [5.8 (4.7–8.8) W/m 2 , p = 0.878]. Myocardial efficiency did not change from baseline to dobutamine [21% (15–27) vs. 31% (20–44), p = 0.059] but decreased significantly during verapamil-induced ischemia [10% (8–13), p = 0.005]. Conclusion: In healthy Landrace pigs, dobutamine stress increased external myocardial power, whereas myocardial efficiency was maintained stable. On the contrary, verapamil-induced ischemia substantially decreased external myocardial power and myocardial efficiency. Non-invasive CMR was able to quantify these efficiency losses and might be useful for future clinical studies evaluating the effects of therapeutic interventions on myocardial energetics.
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Faragli et al. (2021) studied Healthy (n=10). Dobutamine stress and verapamil-induced ischemia vs. Baseline (rest) was evaluated on External myocardial power under dobutamine stress (p=0.005). In healthy Landrace pigs, dobutamine stress significantly increased external myocardial power from 1.3 to 2.3 W/m2 (p=0.005), while verapamil-induced ischemia decreased it to 0.8 W/m2 (p=0.005).
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