Different trends of changes in heart rate variability in patients with anterior and inferior acute myocardial infarction

Heart rhythm complexity analysis in patients with inferior ST-elevation myocardial infarction

Heart rhythm complexity (HRC), a subtype of heart rate variability (HRV), is an important tool to investigate cardiovascular disease. In this study, we aimed to analyze serial changes in HRV and HRC metrics in patients with inferior ST-elevation myocardial infarction (STEMI) within 1 year postinfarct and explore the association between HRC and postinfarct left ventricular (LV) systolic impairment. We prospectively enrolled 33 inferior STEMI patients and 74 control subjects and analyzed traditional linear HRV and HRC metrics in both groups, including detrended fluctuation analysis (DFA) and multiscale entropy (MSE). We also analyzed follow-up postinfarct echocardiography for 1 year. The STEMI group had significantly lower standard deviation of RR interval (SDNN), and DFAα2 within 7 days postinfarct (acute stage) comparing to control subjects. LF power was consistently higher in STEMI group during follow up. The MSE scale 5 was higher at acute stage comparing to control subjects and had a trend of decrease during 1-year postinfarct. The MSE area under scale 1-5 showed persistently lower than control subjects and progressively decreased during 1-year postinfarct. To predict long-term postinfarct LV systolic impairment, the slope between MSE scale 1 to 5 (slope 1-5) had the best predictive value. MSE slope 1-5 also increased the predictive ability of the linear HRV metrics in both the net reclassification index and integrated discrimination index models. In conclusion, HRC and LV contractility decreased 1 year postinfarct in inferior STEMI patients, and MSE slope 1-5 was a good predictor of postinfarct LV systolic impairment.

Autonomic Responses During Acute Anterior Versus Inferior Myocardial Infarction: A Systematic Review and Meta-Analysis

Autonomic responses elicited by myocardial infarction vary depending on the site of injury, but accurate assessment using heart rate variability during the acute phase is limited. We systematically searched PubMed without language restrictions throughout July 2023. We reviewed studies reporting autonomic indices separately for anterior and inferior infarcts, followed by a meta-analysis of those reporting the standard deviation of the inter-beat interval between normal sinus beats during the initial 24 hours after the onset of symptoms. Six studies were included, comprising 341 patients (165 anterior, 176 inferior infarcts), all with satisfactory scores on the Newcastle-Ottawa quality scale. The estimated average of the standardized mean difference (based on the random-effects model) was -0.722 (95% confidence intervals: -0.943 to -0.501), which differed from zero (z=-6.416, p<0.0001). This finding indicates sympathetic and vagal dominance during acute anterior and inferior infarcts, respectively, with excessive responses likely contributing to early arrhythmogenesis. Despite the amelioration of autonomic dysfunction by revascularization, infarct location should be considered when commencing β-adrenergic receptor blockade, especially after delayed procedures.

Vulnerability to cardiac arrest in patients with ST elevation myocardial infarction: Is it time or patient dependent? Results from a nationwide observational study

AIM

Cardiac arrest is a common complication of ST elevation myocardial infarction and is associated with high mortality. We evaluated whether vulnerability to cardiac arrest follows a circadian rhythm and whether it is related to specific patient characteristics.

METHODS

A total of 24,164 ST elevation myocardial infarction patients who were admitted to 60 Belgian hospitals between 2008-2017 were analysed. The proportion of patients with cardiac arrest before initiation of reperfusion therapy was calculated for different time periods (hour of the day, months, seasons) and related to patient characteristics using stepwise logistic regression analysis.

RESULTS

Cardiac arrest occurred in 10.8% of the ST elevation myocardial infarction patients at a median of 65 min (interquartile range 33-138 min) after onset of pain. ST elevation myocardial infarction patients with cardiac arrest showed a biphasic pattern with one peak in the morning and one peak in the late afternoon. Multivariate analysis identified the following independent factors associated with cardiac arrest: cardiogenic shock (odds ratio=28), left bundle branch block (odds ratio=3.7), short (<180 min) ischaemic period (odds ratio=2.2), post-meridiem daytime presentation (odds ratio=1.4), anterior infarction (odds ratio=1.3). Overall in-hospital mortality was 30% for cardiac arrest patients versus 3.7% for non-cardiac arrest patients (p<0.0001).

CONCLUSION

In the present study population, cardiac arrest in ST elevation myocardial infarction showed an atypical circadian rhythm with not only a morning peak but also a second peak in the late afternoon, suggesting that cardiac arrest and ST elevation myocardial infarction triggers are, at least partially, different. In addition, specific patient characteristics, such as short ischaemic period, cardiogenic shock and left bundle branch block, increase the vulnerability to cardiac arrest.

Electrocardiologic and Echocardiographic Features of Patients Exposed to Scorpion Bite

The purpose of this study is to examine clinical progress and hemodynamic and electrocardi ologic features (QT depression and heart rate variability [HRV]) of patients exposed to a scorpion bite.

Seventeen patients bitten by scorpions, and, as a control group, 15 healthy subjects were included in the study. Standard electrocardiograph (ECG) records, 24-hour Holter-ECG, and Doppler echocardiographic examinations were performed.

Holter ECG indicated sinus tachycardia, sinus bradycardia, paroxysmal supraventricular tachycardia, atrial fibrillation, first-degree and second-degree atrioventricular block not requiring treatment, early atrial beats, and early ventricular beats in the patients at frequen cies of 82%, 12%, 35%, 12%, 8%, 70%, and 47%, respectively.

HRV parameters that reflected parasympathetic activity (SD 35 ±13-43 ±16, RMS-SD: 20 ±9-30 ± 12, high frequency: 7.8 ±2-4.3 ±3, p<0.05) were significantly lower (p<0.05). Low frequency, which especially showed sympathetic activity (LF: 11 ± 13-11 ±23, p>0.05), was similar in both groups. In addition, the LF/HF ratio, which reflected sympathovagal balance, was significantly increased in the patient group (1.5 ±1-3.0 ±2, p = 0.005).

Corrected QT and QT dispersion values were not significantly different with respect to the control (p>0.05).

In the patient group compared to the control, a significant decrease was determined in the proportion of mitral E velocity to mitral A velocity (mEv/mAv), diastolic filling period (DFP), and left ventricular ejection fraction (LVEF), while a significant increase was noticed in pulmonary artery pressure (PAP) (mEv/mAv: 0.9 ±0.4-1.7 ±0.6, DFP: 362 ±8.5-425 ±89, LVEF: 53.1 ±6.7-68.6 ±5.8, PAP: 38.1 ±13-27.2 ±6, p<0.05).

Scorpion bite leads to serious cardiovascular disorders, associated with decreased HRV, decreased systolic and diastolic functions, increased arrhythmic events, and hemodynamic disturbance with sympathetic and parasympathetic balance disturbance.

Primary PCI is associated with different cardiac autonomic patterns in relation to the site of myocardial infarction

AIM

Reflex alterations of cardiac autonomic modulation have been described after acute myocardial infarction (AMI). The non-homogeneous autonomic innervation of the heart gives reason of different patterns of autonomic modulation depending upon the site of AMI. Conflicting data are available on cardiac autonomic modifications after primary percutaneous coronary intervention (pPCI). We evaluated cardiac autonomic changes in patients with ST-elevation myocardial infarction (STEMI) after pPCI, either within 24h after revascularization (T0) and at clinical stability (T1, 6±2days), taking into account the site of infarction.

METHODS AND RESULTS

We enrolled 33 consecutive patients with STEMI treated with pPCI (25 males, mean age 61±12.1yr); 15 had an anterior wall STEMI (ANT) and 18 had an inferior wall STEMI (INF). ECG and respiration were recorded at T0 and at T1. Cardiac autonomic modulation was evaluated by means of symbolic analysis of heart rate variability. At T0, At T0, 0V% (marker of sympathetic modulation) was higher in INF compared to ANT [31% (18-43) vs 18% (7-32), p=0.014]. Moreover, ANT had a higher 2LV%, index of vagal modulation, compared to INF [8% (7-15) vs 5% (2-8), p=0.006].

CONCLUSION

After pPCI, these preliminary results suggest that patients with INF were characterized by a sympathetic predominance, while ANT by a predominant vagal modulation. Our data suggest that pPCI can be associated with specific autonomic patterns, which are different for ANT and INF STEMI, according to the different autonomic innervation. Future ad hoc studies are needed to confirm these preliminary observations.

Depressed heart rate response to vasodilator stress for myocardial SPECT predicts mortality in patients after myocardial infarction

BACKGROUND

As heart rate (HR) response during vasodilator stress myocardial perfusion studies can be a marker of HR variability, we investigated its prognostic value in patients after myocardial infarction (MI).

METHODS

Subjects were 147 survivors of MI who underwent vasodilator stress thallium-201 scintigraphy. HR response was measured as peak to basal (P/B) ratios during vasodilator infusion. End points for survival analysis were all-cause deaths, non-fatal recurrent MI, and soft events.

RESULTS

HR response was significantly depressed in the post-MI patients compared to controls (p<0.0005). HR response correlated to LVEF (r=0.37, p<0.0001) and summed stress scores (r=-0.18, p<0.05), but not with antianginal medication. During 58+/-30 mo of follow-up, there were 15 deaths, 7 recurrent MI, and 11 soft events. Low HR response, old age, low LVEF, and high difference score were significant univariate risk factors for death. Multivariate analysis identified low HR response (p=0.03), high stress score (p=0.02), and low LVEF (p=0.05) as independent predictors of mortality. The predictive value of HR response was incremental to that offered by other variables (p=0.02).

CONCLUSIONS

HR response, readily attained during vasodilator stress myocardial perfusion studies, may provide useful additional prognostic information in post-MI patients.

Relationship between the mismatch of 123I-BMIPP and 201Tl myocardial single-photon emission computed tomography and autonomic nervous system activity in patients with acute myocardial infarction

The purpose of this study was to elucidate the relationship between the mismatch of thallium-201(Tl) and iodine-123-beta-methyl-iodophenyl-pentadecanoic acid (BMIPP) myocardial single-photon emission computed tomography (SPECT) and autonomic nervous system activity in myocardial infarction (MI) patients. The subjects were 40 patients (34 males, 6 females) who underwent examinations by 123I-BMIPP and 201Tl myocardial SPECT imaging and 24-hour Holter monitoring within a 3-day period 3 weeks after the onset of their first MI. R-R intervals were analyzed every hour over a period of 24 hours by fast Fourier transformation (FFT). High frequency (HF) and low frequency (LF) were defined as markers of cardiac vagal activity in the former and the LF/HF ratio as sympathetic activity. Greater or more extensive decreases in the BMIPP image than that in the Tl image were defined as a positive mismatch. Patients were divided into positive and negative mismatch groups of 20 patients each. There were no significant differences between the 2 groups in age, sex, site of infarction, max CK (creatine kinase), max CK-MB, or left ventricular ejection fraction. The incidences of clinical signs suggesting residual myocardial ischemia were significantly greater in the positive than in the negative mismatch group (P < 0.05). The mean values for HF over the entire 24-hour period and over the 5-hour nocturnal period (0-5 AM) in the positive mismatch group were both significantly lower than those in the negative mismatch group (P < 0.001 in both groups). The 24-hour mean HF and mean nighttime HF in patients with signs of residual ischemia were both significantly lower than in those without signs of residual ischemia in the positive mismatch group (P < 0.05 in both groups). The mean LF/HF ratio for both the entire 24-hour and the nocturnal period in the positive mismatch group were significantly higher than those in the negative mismatch group (P < 0.001, P < 0.05, respectively). The daily profile of hourly HF measurements was significantly lower in the positive mismatch group than in the negative mismatch group (P < 0.02). The mean values of HF for 24-hour and 5-hour periods were significantly lower in patients with signs of residual ischemia in the positive mismatch group than in those with signs of residual ischemia in the negative mismatch group (P < 0.01, P < 0.02, respectively). There were no significant differences between the patients with signs of residual ischemia in the negative mismatch group and those without signs of residual ischemia in the positive and negative mismatch group with regard to the mean values of HF and the LF/HF ratio measured every hour for 24 hours and 5 hours. It is concluded from the present study that the findings of a mismatch on 123I-BMIPP and 201Tl myocardial SPECT 3 weeks after a first acute myocardial infarction with uncomplicated moderate or severe heart failure and decreased heart rate variability are related to residual myocardial ischemia. A combined assessment of heart rate variability in 24-hour Holter ECG monitoring and perfusion-metabolism mismatch in 123I-BMIPP and 201Tl myocardial SPECT is useful for determining residual myocardial ischemia in the follow-up of those with acute myocardial infarction.

Heart rate versus heart rate variability in risk prediction after myocardial infarction

INTRODUCTION

The aim of this study was to evaluate and compare heart rate and heart rate variability (HRV) in risk prediction after acute myocardial infarction (MI) and to evaluate the effect of beta-blocker treatment on the prognostic performance of heart rate and HRV.

METHODS AND RESULTS

Three hundred sixty-six patients underwent 24-hour Holter recording 1 to 6 days after an MI. HRV was expressed as the standard deviation of all normal-to-normal intervals. Left ventricular systolic function was evaluated using the wall motion index. Half of the patients were taking a beta-blocker at the time of Holter recording. Mean follow-up was 44 months (median 34) after MI. By the end of follow-up, 82 patients had died. Mortality at 1 and 3 years was 12.5% and 22.6%, respectively. HRV, heart rate, wall motion index, number of ventricular premature beats per hour, and ventricular tachycardia were all significantly (P < 0.05) associated with mortality in univariate analysis, independent of beta-blocker therapy. In multivariate Cox analysis, only heart rate, wall motion index, number of ventricular premature beats per hour, and age had independent prognostic value (P < 0.001). In any model, including heart rate, HRV had no predictive value.

CONCLUSION

The prognostic information of HRV is contained completely in heart rate, which carries prognostic information further than that of HRV. This result was independent of beta-blocker treatment.

Evolutionary pattern and prognostic importance of heart rate variability during the early phase of acute myocardial infarction

AIMS

To investigate the evolution of time domain heart rate variability in the early phase of acute myocardial infarction (MI) and assess its prognostic ability.

METHODS

We analysed several measures of heart rate variability (SDNN, SDANN, SDNN index, RMSSD) in 138 patients at days 0, 1 and 5+/-1 after hospital admission for acute MI. Results were correlated with infarct site, clinical variation and clinical outcome (death, MI, PTCA, CABG surgery).

RESULTS

Measures of heart rate variability (SDNN, SDANN and SDNN index) declined during the first 24 h after acute MI (P<0.01) and increased to admission levels after about 5 days. SDNN values on day 0, 1 and 5 respectively were: 86+/-35, 75+/-28 and 87+/-27 ms. Patients with anterior infarction had lower heart rate variability than patients with inferior infarction on all test days but similar evolution patterns. After 3 years of follow-up there were 12 cardiac deaths (8.7%) and six resuscitated arrests and 33 (24%) new MIs, or revascularisation procedures. The evolutionary pattern of heart rate variability was similar in survivors to those who died although values were generally lower. Mortality was significantly higher in the group with SDNN<50 ms at day 1 (P<0.01) and 5 (P<0.05), but not at day 0.

CONCLUSIONS

Our findings show that autonomic imbalance, already evident on the day of the acute event, progresses further over the next 24 h and recovers over the next few days. Low heart rate variability as early as 24 h after acute MI may be a useful predictor of cardiac mortality and contribute to the early risk stratification and therapeutic management of patients.

The effects of trimetazidine on heart rate variability and signal-averaged electrocardiography in early period of acute myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is accompanied by electrophysiological changes in cardiovascular system as well as those in autonomic cardiac control. Heart rate variability (HRV) is depressed due to increased sympathetic activity and/or decreased parasympathetic activity following AMI. Moreover, the frequency of ventricular late potentials (VLP) is increased due to the electrophysiological changes. Based on the hypothesis that the treatments increasing HRV and decreasing the frequency of VLP can improve the prognosis of AMI, we investigated the short-term effects of trimetazidine (TMZ) on HRV and VLP in patients with AMI.

METHODS

The study group consisted of 64 patients (men 49, mean age 55+/-12 years, range 26-70) suffering from first Q-wave AMI. Thirty-one of them were treated with conventional therapy (thrombolytic therapy, aspirin, beta-blocker, heparin and intravenous nitroglycerin) plus TMZ 20 mg tid. The remaining 33 patients served as controls. Holter monitorization between 24 and 48 h, echocardiography at average day 6 (range 4-7 days) and SAECG and sub-maximal exercise at average day 7 (range 6-9 days) were performed to all patients.

RESULTS

While HRV parameters reflecting parasympathetic activity (SDSD: 43+/-16 ms-35+/-13 ms, RMSSD: 34+/-14 ms-27+/-8 ms, HF: 7.8+/-5 ms(2) -4.3+/-4 ms(2), P<0.05) were of significantly higher levels in TMZ group, the low frequency component mainly reflecting sympathetic activity (LF: 10+/-6 ms(2)-10+/-5 ms(2), P>0.05) was similar in both groups. In addition, LF/HF ratio showing sympatho-vagal balance was significantly decreased in TMZ group (1.5-3.0, P=0.005). About VLP, the mean FQRS (105+/-8 ms-107+/-10 ms), LAS (28+/-10 ms-30+/-11 ms) and RMS-40 (34+/-15 microV-41+/-12 microV) were not different in both two groups (P>0.05).

CONCLUSION

Our results suggest that TMZ treatment causes changes in sympatho-vagal balance in favor of vagal activity by increasing parasympathetic activity in AMI at early period; however, no effect on VLP was observed.