Chronic coronary syndromes lead to reduced strain parameters compared to patients without myocardial ischemia in a propensity score-matched cohort assessed by cardiac magnetic resonance imaging

Background

Vasodilator perfusion cardiac magnetic resonance (CMR) has evolved as gold standard in detecting myocardial perfusion deficits (MPD). Even reversible chronic MPD in chronic coronary syndromes can lead to impaired myocardial contractility similar to hibernating myocardium. Feature tracking strain analysis (FTS) provides the opportunity to detect these subclinical alterations of myocardial function before ejection fraction (EF) is impaired. It was therefore the aim of this study to investigate, if subtle changes in myocardial mechanics can be detected by FT strain analysis in patients with MPD.

Methods

Between April 2017 and October 2019 we identified 226 patients with MPD by vasodilator stress CMR out of 1500 patients included in our tertiary care center registry. Propensity score matching was used to identify patients without MPD with similar myocardial characteristics defined by EF, enddiastolic volume indexed by body surface area (EDVi) and native T1-mapping. Steady state free precession cine CMR sequences were analyzed by FTS retrospectively generating three global strain parameters: global longitudinal, circumferential and radial strain (GLS, GCS, GRS).

Results

Propensity score matching yielded 104 patients in each group (MPD mean age 63.6±12.8 years, 25 females; no MPD mean age 67.7±10.6 years, 26 females; LV-EF 51.3±16.0% vs. 52.6±15.2%, p=0.2307; EDVi 88.3±32.7 ml/m2 vs. 82.6±29.3 ml/m2, p=0.1533; native T1 values 1139±60 ms vs. 1125±63 ms, p=0.118). All global strain parameters were significantly reduced in MPD patients compared to patients with no MPD (global longitudinal strain −15.5±4.9 vs. −17.1±4.9, p=0.0046, global circumferential strain −18.0±5.4 vs. −19.4±5.6, p=0.0298; global radial strain 35.4±14.8 vs. 39.4±15.6, p=0.0127).

Conclusion

Chronic Coronary Syndromes cause subtle changes of myocardial mechanics, which are not reflected by EF but can be detected with FTS.

Funding Acknowledgement

Type of funding source: None

P5264There is no significant effect of ischemic time and elapse time since cardiac allograft transplant on myocardial T1 relaxation time

Background

Graft failure caused by allograft rejection and vasculopathy is the most common cause of mortality after heart transplantation. To detect an early allograft rejection, endomyocardial biopsy is still needed. Tissue characterization by T1-mapping and Late gadolinium enhancement is well established in acute and chronic myocardial tissue alterations. Therefore several studies investigated T1-mapping as a potential noninvasive parameter to monitor cardiac allograft vasculopathy and allograft rejection. However it is unclear if T1 is also influenced by pretransplant ischemic time and elapsed time since transplantation.

Purpose

It was the aim of our study to examine the influence of ischemic and elapsed time since transplantation to the cardiac allograft tissue characteristics measured by CMR T1 relaxation times.

Methods

Allograft transplant patients underwent stress CMR on a yearly routine. T1-maps were acquired using a modified look locker sequence (MOLLI 3(2)3(2)5) in the midventricular septum. Uni- and multi linear regression analysis was used to predict T1 by ischemic time, time since transplantation, troponin and NT-Pro-BNP.

Results

49 cardiac allograft transplanted patients underwent stress CMR (mean age 58.6±11.7 years, left ventricular ejection fraction 62.1±6.8%; indexed enddiastolic volume 68.4±14.7 ml/m2; native T1 1120±51 ms, extracellular volume 0.27±0.04). A significant correlation was found between T1 and NT-Pro-BNP (1519±3639 pg/ml, p=0.003) and a trend for troponin (17.0±12.8 ng/dl, p=0.051). We saw no correlation between T1 and the ischemic time (198.4±44.9 minutes, p=0.1172) and elapse time since transplantation (47±7 month, p=0.9868). In the multivariate regression analysis none of the four parameters were independently associated with the T1 time (p=0.1017).

Table 1 Characteristics Mean ± SD p Ischemic time (minutes) 198.4±44.9 0.1172 Time since transplant (month) 47±7 0.9868 NT-Pro-BNP (pg/ml) 1519±3639 0.003 Troponine (ng/dl) 17.0±12.8 0.051

Conclusion

There was no significant effect of pretransplant ischemic time and elapse time since transplantation on native T1 times, whereas native T1 was significantly correlated with troponine and NT-Pro-BNP-Levels. T1 is excellently suited to detect acute changes in allograft transplant patients without being influenced by aging of the transplanted heart and the heart's pretransplant condition.

P5260Differences in myocardial mechanics between dilated cardiomyopathy and ischemic cardiomyopathy by CMR derived feature tracking strain - A propensity score-matched study

Background

Adult heart failure in industrialized nations is primarily due to dilated (DCM) and ischemic cardiomyopathy (ICM). Both diseases are characterized by different pathological pathways. While ICM is predominantly caused by local, subendocardial myocyte necrosis, DCM is characterized by a general myocyte apoptosis involving all myocardial layers. Using feature tracking, longitudinal, circumferential, and radial motion of the left ventricle (LV) can be measured, which allows the function of subendocardial, mostly longitudinal orientated, and subepicardial, mostly circumferential orientated fibers to be assessed independently.

Purpose

It was the aim of our study to detect differences of LV motion between DCM and ICM patients in a propensity score-matched cohort.

Methods

Between April 2017 and December 2018 we included 845 patients with a clinical indication for CMR in our tertiary care center registry. Out of this cohort we identified 273 patients with ICM and 126 with DCM. Propensity score matching was used to pair patients in each group based on their indexed enddiastolic volume (EDVi), ejection fraction (EF), septal T1. Feature tracking technique was used for strain analyses quantified on steady state free precession cine CMR images yielding six strain parameters.

Results

Propensity score matching yielded 59 patients in each group (ICM mean age 59.4±13.0 years, 11 females; DCM mean age 66.5±10.6 years, 15 females; LV-EF 32.6±11.4% vs. 33.0±14.2%, p=0.8178; EDVi 124.2±36 ml/m2 vs. 132.9±42 ml/m2, p=0.0909; native T1 values 1161±66 ms vs. 1164±59 ms, p=0.7049). There was no difference in global longitudinal strain between ICM and DCM patients (−10.9±4.4% vs. −10.6±5.8%, p=0.686), whereas global circumferential strain and radial strain were reduced in DCM patients (−12.0±4.3% vs. −10.31±4.8%, p=0.0190 and 21.1±8.9% vs. 18.0±15.5%, p=0.0386).

Conclusion

Our data confirm the inherently different mechanics of ICM and DCM patients. While myocardial fibres are globally affected in DCM, myocardial damage is predominantly confined to subendocardial layers in ICM despite equally reduced EF.