Research ArticleHEALTH AND MEDICINE

Screening system for drug-induced arrhythmogenic risk combining a patch clamp and heart simulator

See allHide authors and affiliations

Science Advances  01 May 2015:
Vol. 1, no. 4, e1400142
DOI: 10.1126/sciadv.1400142
  • Fig. 1 Diagram of the assay system.

    Dose-inhibition curves of drugs were determined for six ion channels from in vitro experiments using the automated patch clamp system. On the basis of these data, conditions of the in silico heart model under specific drug concentrations were simulated by modulating the channel parameters in cell models of cardiac electrophysiology to yield the 12-lead ECG.

  • Fig. 2 Dose-inhibition relation of drugs on ion currents.

    Left column (top to bottom): amiodarone, astemizole, bepridil, cisapride, dofetilide, and d-sotalol. Right column (top to bottom): E-4031, moxifloxacin, quinidine, ranolazine, terfenadine, and verapamil. In each graph, relative activities of ion currents are plotted as a function of drug concentration in logarithmic scale. Black line, INa; black dotted line, INaL; red line, ICa; dark blue line, IKr; green line, IKs; light blue line, IK1; orange line, Ito; green circle, ETPCunbound.

  • Fig. 3 In silico risk assessment of drug-induced arrhythmogenesis.

    (A and B) Two-lead ECGs with varying doses of drugs (control, 1×, 10×, 30×, 50× of ETPCunbound) are shown for cisapride (A) and verapamil (B) at HR = 40 bpm (left column) and HR = 60 bpm (right column). For both drugs, a dose-dependent prolongation of QT intervals was observed, although TdP was only observed for cisapride. (C) Threshold values relative to ETPCunbound are shown for each drug categorized as high risk (1, 2, and 3) or safe (4 and 5). TdP was not observed for drugs in categories 4 and 5. ND, not detected.

  • Fig. 4 Comparison of the predictability of currently proposed biomarkers for arrhythmogenic risk for drugs in each category.

    (A) Threshold (Th) for TdP (current method). For drugs not inducing TdP, an ○ value is assigned at HR = 60. (B) hERG inhibition quantified by hERG IC50/ETPCunbound. (C) Prolongation of QT interval at the ETPC. (D) MICE model evaluated as −log(Cav1.2 IC50) + log(hERG IC50). d,l-Sotalol was not evaluated for the MICE model because Cav1.2 IC50 could not be identified. (E) TDR measured by the difference between maximum and minimum action potential durations under maximum tolerable concentration without arrhythmia. Concentrations are 100 (amiodarone), 100 (astemizole), 5 (bepridil), 10 (cisapride), 30 (dofetilide), 50 (d,l-sotalol), 5 (E-4031), 100 (moxifloxacin), 1 (quinidine), 20 (ranolazine), 10 (terfenadine), and 50 (verapamil) times ETPC. Except for the present method, values of biomarkers were distributed evenly among the categories.

  • Fig. 5 Effect of the number of channels assayed on risk prediction.

    (A) Drug effect of quinidine on ECG simulated using the data on six (left), four (middle), and three (right) channels (ch). When using the data on only three channels, arrhythmogenicity was not reproduced. (B) Relative threshold values for TdP of each drug examined using the data on three (red), four (blue), and six (black) channels. A difference was detected in quinidine.

  • Fig. 6 Significance of the three-dimensional heart model with realistic tissue structure for the accurate prediction of arrhythmogenic risk.

    Effects of varying doses of quinidine up to 10 times of ETPCunbound on ECG were evaluated using the model with three types of ventricular myocytes (endocardial, M, and epicardial cells) arranged transmurally (physiological), endocardial cell only (endo), M cell only (M), epicardial cell only (epi), and two-layered model with epicardial and endocardial cells (epi, endo). Arrhythmia was observed only in the physiological model, suggesting the importance of three-dimensional heart simulation with realistic tissue structure in which inhibition of IKs augmented the TDR.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/1/4/e1400142/DC1

    Fig. S1. Simulated 12-lead ECG.

    Fig. S2. Drug effects on two-lead ECG.

    Fig. S3. Effect of hypothetical multichannel blockers on ECG.

    Fig. S4. Effect of cisapride for a subject carrying a common polymorphism of hERG channel.

    Fig. S5. Effect of concomitant use of clarithromycin on the arrhythmogenicity of amiodarone.

    Fig. S6. Effect of irregular heartbeats.

    Table S1. Inhibitory actions of 12 drugs on six ion channels.

    Table. S2. Abbreviations.

    Movie S1. Simulation of regular heartbeat.

    Movie S2. Simulation of drug-induced arrhythmia.

    Reference (36)

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Simulated 12-lead ECG.
    • Fig. S2. Drug effects on two-lead ECG.
    • Fig. S3. Effect of hypothetical multichannel blockers on ECG.
    • Fig. S4. Effect of cisapride for a subject carrying a common polymorphism of hERG channel.
    • Fig. S5. Effect of concomitant use of clarithromycin on the arrhythmogenicity of amiodarone.
    • Fig. S6. Effect of irregular heartbeats.
    • Table S1. Inhibitory actions of 12 drugs on six ion channels.
    • Table. S2. Abbreviations.
    • Reference (36)

    Download PDF

    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mpg format). Simulation of regular heartbeat.
    • Movie S2 (.mpg format). Simulation of drug-induced arrhythmia.

    Files in this Data Supplement:

Navigate This Article