In-hospital predictors for primary prevention of sudden death after acute myocardial infarction with cardiac dysfunction

BACKGROUND

Current guidelines recommend prophylactic defibrillator implantation in patients with acute myocardial infarction (AMI) and left ventricular ejection fraction (LVEF) ≤40 % or LVEF ≤35 % plus heart failure symptoms or inducible ventricular tachyarrhythmias during an electrophysiology study at 40 days after AMI or 90 days after revascularization. In-hospital predictors of sudden cardiac death (SCD) after AMI during the index hospitalization remain unsettled. We sought to examine in-hospital predictors of SCD in patients with AMI and LVEF ≤40 % evaluated during the index hospitalization.

METHODS

We retrospectively evaluated 441 consecutive patients with AMI and LVEF ≤40 % admitted to our hospital between 2001 and 2014 (77 % male gender; median age: 70 years; median hospitalization length: 23 days). The primary endpoint was a composite of SCD or aborted SCD at ≥30 days after AMI onset (composite arrhythmic event). LVEF and QRS duration (QRSd) on electrocardiography were measured at a median of 12 days and 18 days, respectively.

RESULTS

During a median follow-up of 7.6 years, the incidence of composite arrhythmic events was 7.3 % (32 of 441 patients). In multivariable analysis, QRSd ≥100 msec (beta-coefficient = 1.54, p = 0.003), LVEF ≤23 % (beta-coefficient = 1.14, p = 0.007), and onset-reperfusion time > 5.5 h (beta-coefficient = 1.16, p = 0.035) were independent predictors of composite arrhythmic events. The combination of these 3 factors was associated with the highest rate of composite arrhythmic events compared with 0-2 factors (p < 0.001).

CONCLUSIONS

The combination of QRSd ≥100 msec, LVEF ≤23 %, and onset-reperfusion time > 5.5 h during the index hospitalization provides precise risk stratification for SCD in patients early after AMI.

Implantable cardioverter defibrillator and survival after out-of-hospital cardiac arrest due to acute myocardial infarction in Denmark in the years 2001-2012, a nationwide study

AIM

The purpose of this study was to describe the implantation of implantable cardioverter defibrillator after out-of-hospital cardiac arrest caused by myocardial infarction in Denmark 2001-2012 and subsequent survival.

METHODS

The Danish Cardiac Arrest Registry was used to identify patients ⩾18 years surviving to discharge without prior implantable cardioverter defibrillator. Information on cardioverter defibrillator implantation was obtained from the National Patient Registry.

RESULTS

We identified 974 myocardial infarction-out-of-hospital cardiac arrest patients surviving to hospital discharge, 130 of these patients (13%) had a cardioverter defibrillator implanted early (⩽40 days post-out-of-hospital cardiac arrest), 58 patients (6%) had late implantable cardioverter defibrillator (41-365 days post-out-of-hospital cardiac arrest). Odds of implantable cardioverter defibrillator implantation within one year were higher in patients receiving cardiopulmonary resuscitation (odds ratio (OR)_CPR: 1.99, confidence interval (CI): 1.23-3.22, p=0.01), and Charlson Comorbidity Index level 1, (OR_CCI1: 2.10, CI:1.25-3.49, p<0.01). Odds of a late implantable cardioverter defibrillator was higher in patients undergoing percutaneous coronary intervention (PCI) (OR_PCI: 3.67, CI: 1.35-9.97, p=0. 01). An early, but not late implantable cardioverter defibrillator was associated with increased survival (event time ratio_{Early ICD}: 1.45, CI: 1.11-1.90, p=0.01). Chronic heart failure, higher age groups, Charlson Comorbidity Index levels 1 to ⩾3 and male sex were associated with lower survival. Highest income was associated with higher survival.

CONCLUSION

Cardioverter defibrillator implantation rates in patients surviving an myocardial infarction-out-of-hospital cardiac arrest increased from 14% to 19% over the period. Of the total patient population, 13% had implantation earlier than recommended by guidelines, presumably as primary prevention of sudden cardiac death. Acute PCI and arrest later in the study period (increase one year) were predictors of late cardioverter defibrillator implantation. Early cardioverter defibrillator implantation was significantly associated with a long-term survival benefit, later implantation was not.

Evolution of Left Ventricular Ejection Fraction After Acute Myocardial Infarction

Background—

Implantable cardioverter-defibrillator therapy improves survival in patients with reduced left ventricular ejection fraction (LVEF) after acute myocardial infarction (AMI). Although the risk of sudden cardiac death is highest in the first month after AMI, there is no survival benefit of early implantable cardioverter-defibrillator implantation, and the optimal time frame has yet to be established. Thus, the aim of this study was to investigate what proportion of post-AMI patients had improved LV function to such an extent that the indication for implantable cardioverter-defibrillator was no longer present.

Methods and Results—

Patients admitted for AMI with reduced LVEF (≤40%) were eligible for inclusion. Repeat echocardiographic examinations were performed 5 days, 1 month, and 3 months after the AMI. We prospectively included 100 patients with LVEF of 31±5.8% after AMI. At the 1-month follow-up, 55% had an LVEF >35%. The main improvement in LVEF had occurred by 1 month. The mean difference in LVEF over the next 2 months was small, 1.9 percentage units. During the first 9 weeks, 10% of the patients suffered from life-threatening arrhythmias.

Conclusions—

Most patients have improved LVEF after AMI, and in the majority, the improvement can be confirmed after 1 month, implying that further delay of implantable cardioverter-defibrillator implantation may not be warranted. Life-threatening arrhythmias occurred in 10% of the patients, illustrating the high risk for sudden cardiac death in this population.

In-hospital heart rate turbulence and microvolt T-wave alternans abnormalities for prediction of early life-threatening ventricular arrhythmia after acute myocardial infarction

BACKGROUND

In the setting of primary prevention, most implantable cardiac defibrillators (ICD) are implanted more than 6 months after acute myocardial infarction (AMI). Abnormal heart rate turbulence (HRT) and T-wave alternans (TWA) are predictors of long-term sudden cardiac death (SCD). We intended to assess the predictive value of HRT and TWA for early post-AMI SCD and life-threatening ventricular arrhythmias (VA).

METHODS

One hundred ninety-nine consecutive patients with AMI were prospectively included (age 61.7 years, LV ejection fraction 45%). One hundred eighty-three patients (92%) underwent percutaneous coronary intervention. We assessed HRT using turbulence slope (TS), turbulence onset (TO), and TWA on channels 1 and 2 (TWA1 and TWA2) using the modified moving average method. Predictive performance for SCD/VA was assessed by area under the receiver operating curve characteristic (ROC-AUC).

RESULTS

Within 6 months after AMI, 2 patients (1%) developed life-threatening VA and 3 (1.5%) experienced SCD. TO and TWA1 had poor ROC-AUC (both 0.64) whereas TS and TWA2 failed to show any predictive performance (ROC-AUC 0.48 and 0.57, respectively). When combining TO and TWA1, ROC-AUC increased to 0.80. Importantly, when considering the subset of patients with a LV ejection fraction ≤40%, the combined variable of TO and TWA1 remained strongly predictive of a short-term event (ROC-AUC 0.86).

CONCLUSIONS

Combined assessment of HRT and TWA showed a high predictive performance for SCD or life-threatening VA within 6 months after AMI. This combined Holter ECG index could be useful to identify high-risk patients who might benefit from early ICD implantation.