Influence of standard modifiable risk factors on ventricular tachycardia after myocardial infarction

Background

Inducible ventricular tachycardia (VT) at electrophysiology study (EPS) predicts sudden cardiac death because of ventricular tachyarrhythmia, the single greatest cause of death within 2 years after myocardial infarction (MI).

Objectives

We aimed to assess the association between standard modifiable risk factors (SMuRFs) and inducible VT at EPS early after MI.

Methods

Consecutive patients with left ventricle ejection fraction ≤40% on days 3-5 after ST elevation MI (STEMI) who underwent EPS were prospectively recruited. Positive EPS was defined as induced sustained monomorphic VT cycle length ≥200 ms for ≥10 s or shorter if hemodynamically compromised. The primary outcome was inducibility of VT at EPS, and the secondary outcome was all-cause mortality on follow-up.

Results

In 410 eligible patients undergoing EPS soon (median of 9 days) after STEMI, 126 had inducible VT. Ex-smokers experienced an increased risk of inducible VT [multivariable logistic regression adjusted odds ratio (OR) 2.0, p = 0.033] compared with current or never-smokers, with comparable risk. The presence of any SMuRFs apart from being a current smoker conferred an increased risk of inducible VT (adjusted OR 1.9, p = 0.043). Neither the number of SMuRFs nor the presence of any SMuRFs was associated with mortality at a median follow-up of 5.4 years.

Conclusions

In patients with recent STEMI and impaired left ventricular function, the presence of any SMuRFs, apart from being a current smoker, conferred an increased risk of inducible VT at EPS. These results highlight the need to modify SMuRFs in this high-risk subset of patients.

The cardiothoracic ratio: a neglected preoperative risk-stratified method for patients with rheumatic heart disease undergoing valve replacement surgery

OBJECTIVES

It is common for patients with rheumatic heart disease to have an enlarged heart. We investigated the prognostic value of cardiothoracic ratio (CTR) in patients with rheumatic heart disease undergoing valve replacement surgery.

METHODS

A total of 1772 patients were divided into 4 groups based on the quartiles of preoperative CTR: <0.56 (n = 349), 0.56-0.61 (n = 488), 0.61-0.66 (n = 449) and ≥0.66 (n = 486). The CTR was measured from postero-anterior chest radiographs. We then investigated the association between the CTR and adverse outcomes.

RESULTS

In-hospital mortality was 4.0% (71/1772). Analyses of receiver operating characteristic curves showed that, at a cut-off of 0.6, the CTR exhibited 66.2% sensitivity and 64.0% specificity for detecting in-hospital death (area under curve 0.671, P < 0.001). The prevalence of in-hospital death was 7.1% in males with a CTR >0.6, which was significantly higher in males without a CTR. A similar result was observed in females (1.9 vs 5.1%, P = 0.004). Multivariable regression showed that a CTR >0.6 was an independent predictor of in-hospital (odds ratio 2.36, P = 0.005) and 1-year mortality (hazard ratio 2.06, P = 0.006). Kaplan-Meier curves, for the cumulative rate of 1-year mortality among groups, indicated that the risk of death was increased if the CTR >0.6 (log-rank 16.36, P < 0.001).

CONCLUSIONS

CTR, as a simple and reproducible indicator, was identified as a prognostic factor for predicting poor outcomes in patients with rheumatic heart disease undergoing valve replacement surgery.

Sex Differences in Electrophysiology, Ventricular Tachyarrhythmia, Cardiac Arrest and Sudden Cardiac Death Following Acute Myocardial Infarction

BACKGROUND

Women experience less appropriate implantable cardioverter-defibrillator (ICD) interventions and are underrepresented in randomised ICD trials. Sex-differences in inducible and spontaneous ventricular tachycardia/fibrillation (VT/VF), cardiac arrest and sudden cardiac death (SCD) early post-myocardial infarction (MI) require further study.

METHODS

Consecutive ST-elevation MI patients with left ventricular ejection fraction (LVEF)≤40% underwent electrophysiology study (EPS) to target early prevention of SCD. An ICD was implanted for a positive (inducible monomorphic VT) but not a negative (no arrhythmia or inducible VF) EPS. The combined primary endpoint of VT/VF (spontaneous or ICD-treated), cardiac arrest or SCD was assessed using competing risk survival analysis in women versus men with adjustment for confounders. Logistic regression was used to determine independent predictors of inducible VT at EPS.

RESULTS

A total of 403 patients (16.9% female) underwent EPS. Women were significantly older than men but with similar LVEF (31.5 ± 6.3 versus 31.6 ± 6.4%, p = 0.91). Electrophysiology study was positive for inducible VT in 22.1% and 33.4% (p = 0.066) and an ICD implanted in 25.0% and 33.4% (p = 0.356) of women versus men. Appropriate ICD activations (VT/VF) occurred in 5.9% of women and 36.6% of men (p = 0.012). The adjusted cumulative primary endpoint incidence was significantly lower in women than men (1.6% versus 26.5%, p = 0.03). Female sex was not an independent predictor of inducible VT at EPS (HR 0.63, 95% CI 0.33-1.23, p = 0.178).

CONCLUSIONS

Women with early post-MI cardiomyopathy had lower VT/VF, cardiac arrest and SCD, compared to men. In ICD recipients the rate of appropriate activations was six-fold less in women compared to men.

Driving with cardiac devices in Australia. Does a review of recent evidence prompt a change in guidelines?

Australian Driving Guidelines for patients with pacemakers and implanted cardioverter defibrillators are in line with many around the world, with some minor differences. Some aspects of these guidelines lack contemporary evidence in key decision-making areas and make broad recommendations regarding groups with heterogeneous populations. In addition, more recent studies suggest lower rates of adverse events in some patients with these devices than previously thought. Through a systematic literature review, along with discussion of current guidelines, we combine new evidence with well established risk assessment tools to ask the following questions: (i) Given the heterogeneity of patient risk within the defibrillator population, should guidelines allow for further individualisation of risk and subsequent licensing restrictions?; and (ii) Could some patients with primary prevention automated cardioverter defibrillators be able to hold a commercial driving licence?