ECG analysis
| Sham | PMI | BNP-PMI | BB-PMI | BB-BNP-PMI | |
|---|---|---|---|---|---|
| ECG parameters | |||||
| Heart rate (bpm) | 593±11 | 630±12* | 665±10†,§ | 536±12*,|| | 539±12*,|| |
| QRS duration (ms) | 17.4±1.1 | 32.8±1.4† | 33.1±1.1† | 33.5±1.2† | 28.2±0.9*,§,¶ |
| QTc interval (ms) | 32.2±1.3 | 51.3±1.4† | 59.5±1.6‡ | 46.4±3.2†,§ | 45.7±2.4†,§ |
| QTSTV (ms) | 178±34 | 362±31† | 454±45† | 285±33‡,§ | 149±55||,¶ |
| Heart rate variability | |||||
| LF (ms2) | 0.052±0.005 | 0.012±0.009† | 0.009±0.004† | 0.028±0.005†,§ | 0.041±0.004*,||,¶ |
| HF (ms2) | 0.032±0.005 | 0.028±0.009 | 0.025±0.006 | 0.032±0.005 | 0.033±0.009 |
| LF to HF | 1.62±0.11 | 0.43±0.12† | 0.36±0.28† | 0.87±0.27*,§ | 1.24±0.19*,||,¶ |
| SDNN (ms) | 14.9±2.4 | 9.1±1.4* | 5.8±1.3† | 13.5±2.1§ | 18.1±2.1||,¶ |
| RMSSD (ms) | 5.7±0.9 | 3.18±0.8* | 3.54±1.1* | 3.7±1.0* | 3.6±1.1* |
| VA | |||||
| Number of VA | 21.3±4.2 | 44.7±3.1† | 56.2±2.7† | 28.3±4.2§ | 16.6±2.4||,¶ |
| SVT (%) | |||||
| During treatment | 8 | 50† | 66‡,§ | 0|| | 8|| |
| After treatment | 0 | 58† | 58† | 33§ | 8||,¶ |
BB+BNP improved heart rate variability and were more efficient than metoprolol alone to prevent variability of ventricular repolarisation and VA. Parameters estimated from 12 h nocturnal ECG: heart rate, QRS duration, corrected QT interval (QTc) and short term variability of QT (QTSTV). Heart rate variability analysis in the frequency- and time-domain with low frequencies (LF), high frequencies (HF) spectral power, LF to HF ratio, SD of all normal R-R intervals (SDNN) and square root of the mean square successive differences between successive normal R-R intervals (RMSSD). Number of spontaneous ventricular extrasystoles (VA) developed over 12 h ECG recording. Percentage of mice developing SVT following injection of isoproterenol (2.5 mg/kg intraperitoneal) during and assessed 4 weeks after treatment. *,†,‡ p<0.05, p<0.01, p<0.001 versus Sham; §,|| p<0.05, p<0.01 versus PMI; ¶ p<0.05 versus BB-PMI; n=15/group.
BB, β1-adrenergic blocker; BNP, B-type natriuretic peptide; PMI, postmyocardial infarction; SVT, sustained ventricular tachycardia; VA, ventricular arrhythmia.