Force-based left ventricular contractile reserve, a novel stress echocardiographic marker

Stress echocardiography, often done by giving a dobutamine infusion in graded doses, assesses regional wall motion abnormality for indicating critical epicardial coronary artery stenosis. That mostly determines subendocardial underperfusion. Recent introduction of evaluation of left ventricular contractile reserve based on force has enriched the core protocol of stress echocardiography. Left ventricular contractile reserve is the difference between the basal and peak stress (either exercise or pharmacological) left ventricular ejection fraction. It unmasks latent dysfunction that may not be visible while the patient is at rest. But LVEF is dependent on preload and afterload, that is related to ventricular volume and blood pressure.

The newer, more robust echocardiographic marker is Force-based LVCR:

Force = Systolic blood pressure/End systolic volume

LVCR = Force at stress/Force at rest

This ratio is relatively load-independent, making it a truer measure of the health of left ventricular muscle. Systolic blood pressure can be determined by a sphygmomanometer and end systolic volume by echocardiography [1]. Changes in force can be caused by microvascular and/or epicardial coronary artery disease. It can also be affected by myocardial scar, necrosis or disease of the sub-epicardial layer.

Normal Value: Typically > 2.0 for exercise/dobutamine or > 1.1 for vasodilators. Lower value for vasodilator is because that is a weaker inotropic stimulus.

International Stress Echo 2020 Study evaluated the prognostic value of LVCR both in ischemic and non-ischemic heart disease [2]. The study used ABCDE protocol for coronary artery disease. Step A, regional wall motion abnormalities on stress echo; step B, B lines on lung ultrasound; step C, left ventricular contractile reserve; step D, Doppler-based coronary flow velocity reserve in left anterior descending coronary artery; and step E, electrocardiogram-based heart rate reserve. The study showed that the protocol was effective in prediction of survival in patients with chronic coronary syndromes [3]. B lines on lung ultrasound indicate pulmonary edema.

In addition, the study had 10 sub projects focussing on: contractile reserve for prediction of cardiac resynchronization or medical therapy response, stress B-lines in heart failure; hypertrophic cardiomyopathy; heart failure with preserved ejection fraction; mitral regurgitation after either transcatheter or surgical aortic valve replacement; outdoor stress echo in extreme physiology; right ventricular contractile reserve in repaired Tetralogy of Fallot; suspected or initial pulmonary arterial hypertension; coronary flow velocity, left ventricular elastance reserve and B-lines in known or suspected coronary artery disease. So it was a major project and we can look out for more reports.

References

1. Picano E, Bombardini T, Kovačević Preradović T, Cortigiani L, Wierzbowska-Drabik K, Ciampi Q. Left ventricular contractile reserve in stress echocardiography: the bright side of the force. Kardiol Pol. 2019;77(2):164-172. doi: 10.5603/KP.a2019.0002. Epub 2019 Jan 15. PMID: 30644080.
2. Picano E, Ciampi Q, Citro R, D’Andrea A, Scali MC, Cortigiani L, Olivotto I, Mori F, Galderisi M, Costantino MF, Pratali L, Di Salvo G, Bossone E, Ferrara F, Gargani L, Rigo F, Gaibazzi N, Limongelli G, Pacileo G, Andreassi MG, Pinamonti B, Massa L, Torres MA, Miglioranza MH, Daros CB, de Castro E Silva Pretto JL, Beleslin B, Djordjevic-Dikic A, Varga A, Palinkas A, Agoston G, Gregori D, Trambaiolo P, Severino S, Arystan A, Paterni M, Carpeggiani C, Colonna P. Stress echo 2020: the international stress echo study in ischemic and non-ischemic heart disease. Cardiovasc Ultrasound. 2017 Jan 18;15(1):3. doi: 10.1186/s12947-016-0092-1. PMID: 28100277; PMCID: PMC5242057.
3. Ciampi Q, Zagatina A, Cortigiani L, Wierzbowska-Drabik K, Kasprzak JD, Haberka M, Djordjevic-Dikic A, Beleslin B, Boshchenko A, Ryabova T, Gaibazzi N, Rigo F, Dodi C, Simova I, Samardjieva M, Barbieri A, Morrone D, Lorenzoni V, Prota C, Villari B, Antonini-Canterin F, Pepi M, Carpeggiani C, Pellikka PA, Picano E. Prognostic value of stress echocardiography assessed by the ABCDE protocol. Eur Heart J. 2021 Oct 1;42(37):3869-3878. doi: 10.1093/eurheartj/ehab493. PMID: 34449837; PMCID: PMC8486488.