Living myocardial slices retain patient-specific features: Insights into etiology and therapeutic history

Figures

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  Figure 1. LMS reflect patient-specific functional variability and the impact of LVAD-induced mechanical unloading. (A) PCA of key functional parameters (refractory period, threshold potential, contractile force, post pause potentiation at 30 seconds, diastolic tension, and force-frequency relationship at 240 bpm), showing patient-specific grouping. Ellipses represent the standard deviation per patient. (B) Euclidean distance analysis reveals lower intrapatient functional variability compared to interpatient variability (A and B: N = 12, n = 138). (C) PCA was regrouped by the presence or absence of LVAD at the time of heart explantation and LMS preparation. (D) Euclidean distances between LVAD and no-LVAD patients highlight a decreased intrapatient variability in LVAD patients (C and D: LVAD, N = 8, n = 73; no LVAD, N = 2, n = 29). (E) Positive correlation between NT-proBNP levels, a marker for ventricular pressure and stress, and diastolic tension in LMS (E: N = 10, n = 102). A Wilcoxon rank-sum test was used to compare Euclidean distances, and Pearson correlation was performed to assess associations with NT-proBNP. p < 0.05 was considered statistically significant. LMS, living myocardial…

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  Figure 2. Functional characterization of LMS based on patient etiology. (A) PCA of key functional parameters showing distinct clustering of LMS based on etiology (TTN, non-TTN, ICM, and non-ICM). Ellipses represent the standard deviation per patient. (B) LMS from patients with a TTN mutation exhibit stronger contractile force compared to other etiologies. (C) Post pause potentiation after a 3-, 12-, and 30-second pause is significantly higher in LMS from non-TTN groups, particularly for longer pause durations. (D) Interaction between etiology and pacing frequency reveals distinct responses: LMS from non-TTN etiology show stronger contractile force at lower frequencies, while LMS from ICM patients demonstrate enhanced force at higher frequencies (A-D: TTN, N = 3, n = 31; non-TTN, N = 3, n = 48; ICM, N = 3, n = 21; non-ICM, N = 3, n = 38). One-way ANOVA with Tukey’s posthoc test and mixed-effects analysis were used where appropriate. p < 0.05 was considered statistically significant. ICM, ischemic cardiomyopathy; LMS, living myocardial slices; TTN, titin.

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  Figure 3. Effect of amiodarone on LMS function. (A) A representative LC-MS trace showing the retention time (RT) of 2.8 seconds, corresponding to amiodarone isolated from epicardial fat and LMS, as confirmed by comparison with the amiodarone standard. (B) PCA of functional parameters showing distinct clustering of LMS from amiodarone-treated vs untreated patients. (C) LMS from amiodarone-treated patients exhibit a higher threshold potential. (D) Post pause potentiation is enhanced in amiodarone-treated LMS, particularly at longer pause durations. (E) Force-frequency assessment reveals weaker contractile force in LMS from amiodarone-treated patients at higher pacing frequencies. (B-E: amiodarone N = 7, n = 66; no amiodarone N = 5, n = 70). Welch’s t-test and mixed-effects models with posthoc analysis were used where appropriate. p < 0.05 was considered statistically significant. LMS, living myocardial slices; PCA, principal component analysis.

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  Figure 4. Effect of amiodarone on LMS electrophysiological properties. (A) LMS from amiodarone-treated patients exhibit prolonged APD90 compared to untreated LMS. (B) APD90 in treated LMS fails to adapt to increased pacing frequency. (C) LMS derived from amiodarone-treated patients are unable to maintain pacing at 3 Hz, unlike the LMS from patients without amiodarone. (D, E) CTD90 shows an interaction between pacing interval and amiodarone treatment, though no significant differences are observed in posthoc analysis. (F) Calcium transient analysis reveals an inability of LMS from patients treated with amiodarone to follow pacing at 3 Hz, though less pronounced than for action potentials. (A-F: amiodarone, N = 6, n = 17; no amiodarone, N = 4, n = 11). A mixed-effects model with posthoc analysis was used to compare amiodarone and no amiodarone. p < 0.05 was considered statistically significant. APD, action potential duration; CTD, calcium transient duration; LMS, living myocardial slices.