Abstract
Acute myocardial infarction (AMI) can progress to heart failure, which has a poor prognosis. Normally, 60% of stroke volume (SV) is attributed to the longitudinal ventricular shortening and lengthening evident in the atrioventricular plane displacement (AVPD) during the cardiac cycle, but there is no information on how the relationship changes between SV and AVPD before and after AMI. Therefore, the aim of this study was to determine how SV depends on AVPD before and after AMI in two swine models. Serial cardiac magnetic resonance imaging was carried out before and 1–2 h after AMI in a microembolization model (n = 12) and an ischemia-reperfusion model (n = 14). A subset of pigs (n = 7) were additionally imaged at 24 h and at 7 days. Cine and late gadolinium enhancement images were analyzed for cardiac function, AVPD measurements and infarct size estimation, respectively. AVPD decreased (P < 0.05) in all myocardial regions after AMI, with a concomitant SV decrease (P < 0.001). The ischemia-reperfusion model affected SV to a higher degree and had a larger AVPD decrease than the microembolization model (−29 ± 14% vs. −15 ± 18%; P < 0.05). Wall thickening decreased in infarcted areas (P < 0.001), and A-wave AVPD remained unchanged (P = 0.93) whereas E-wave AVPD decreased (P < 0.001) after AMI. We conclude that AVPD is coupled to SV independent of infarct type but likely to a greater degree in ischemia-reperfusion infarcts compared with microembolization infarcts. AMI reduces diastolic early filling AVPD but not AVPD from atrial contraction. These findings shed light on the physiological significance of atrioventricular plane motion when assessing acute and subacute myocardial infarction.NEW & NOTEWORTHY The link between cardiac longitudinal motion, measured as atrioventricular plane displacement (AVPD), and stroke volume (SV) is investigated in swine after acute myocardial infarction (AMI). This cardiac magnetic resonance study demonstrates a close coupling between AVPD and SV before and after AMI in an experimental setting and demonstrates that this connection is present in ischemia-reperfusion and microembolization infarcts, acutely and during the first week. Furthermore, AVPD is equally and persistently depressed in infarcted and remote myocardium after AMI.
Highlights
Heart failure (HF) is a major global health burden, and an estimated 6.5 million adults are suffering from this condition in the United States alone [3]
stroke volume (SV), end-diastolic volume (EDV), and endsystolic volume (ESV) were larger in the Ischemia-Reperfusion group compared with the Microembolization group (P Ͻ 0.01 for all)
Cardiac output (CO) decreased differently in Ischemia-Reperfusion and Microembolization groups compared with baseline [Ϫ17 Ϯ 30% (P Ͻ 0.05) and Ϫ37 Ϯ 19% (P Ͻ 0.001), respectively]
Summary
Heart failure (HF) is a major global health burden, and an estimated 6.5 million adults are suffering from this condition in the United States alone [3]. Longitudinal shortening of the ventricles, called mitral annular plane systolic excursion, is essential for normal pumping and filling [20]. It can be measured as the atrioventricular (AV) plane displacement (AVPD) with ultrasound [24] or cardiac magnetic resonance imaging (CMR) [13]. The longitudinal lengthening in diastole results in a scooping of the AV plane over atrial blood, resulting in diastolic filling [12] To this end, it is important to know 1) the extent to which different myocardial ischemic injuries alter AVPD and SV and 2) how the relationship between AVPD and SV changes with different types of myocardial injury
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