Examining Criteria for ICD Primary Prevention Therapy

The Particulars: Studies have suggested that nearly 25% of implantable cardioverter-defibrillators (ICDs) for primary prevention are implanted outside of evidence-based criteria. Currently, there is little information comparing the long-term outcomes among patients receiving ICDs within evidence-based guidelines and those outside of such criteria.

Data Breakdown: A retrospective analysis of patients who received ICDs for primary prevention found that those who received their device outside of evidence-based criteria experienced similar results to those within such criteria. Similar findings were observed in time to first appropriate ICD therapy, risk of death, and time of first inappropriate ICD therapy.

Take Home Pearl: Patients who receive ICDs for primary prevention outside of evidence-based criteria appear to experience similar therapeutic benefits and outcomes as patients who receive their device within evidence-based criteria.

Real-World Results With Subcutaneous ICD

The Particulars: The Subcutaneous Implantable Cardioverter-Defibrillator (S-ICD) System does not require the intravascular leads used in typical transvenous implantable cardioverter-defibrillator (ICD) procedures. The device is inserted under the skin and outside the ribcage of patients at risk for sudden cardiac arrest (SCA). Long-term performance of the S-ICD System, including patient quality of life and long-term resource use, has yet to be studied.

Data Breakdown: Researchers reviewed the real-world experiences of 230 recipients of the S-ICD System in nine countries. They found a conversion rate of more than 98% for induced and ambulatory ventricular tachycardia or fibrillation. No patients received therapy for any supraventricular tachycardia within a programmed conditional shock zone.

Take Home Pearl: According to real-world experiences, the S-ICD System appears to be a safe and effective option for most patients requiring protection from SCA.

Obesity Raises Sudden Cardiac Death Risk

The Particulars: Obesity is widely recognized as a moderate risk factor for sudden cardiac death (SCD). However, there are currently gaps in the literature with regard to information on the nature of this association.

Data Breakdown: An analysis of more than 15,000 people with SCD examined the association between BMI, waist circumference (WC), and waist-to- hip ratio (WHR). BMI, WC, and WHR were positively associated with SCD after adjusting for multiple factors. After further adjustment for obesity-related comorbidities, WHR was independently associated with SCD.

Take Home Pearls: In the general population, obesity appears to be associated with SCD. After accounting for multiple factors and obesity-related comorbidities, WHR appears to be independently associated with SCD.

The Role of Gender in Arrhythmic Event Rates

The Particulars: Previous investigations have indicated that appropriate therapies for ventricular arrhythmia are less likely to be obtained by women with ischemic heart disease. The influence of gender on arrhythmic events between men and women warrants further study.

Data Breakdown: Cardiac arrhythmia rates were determined for nearly 1,800 patients over 3 years in an analysis. During follow-up, 16% of women and 28% of men experienced a ventricular arrhythmia-related event or died. While average ventricular tachycardia (VT) cycle lengths were significantly shorter in men than women, lengths did not differ significantly for ventricular fibrillation (VF). For implantable cardioverter-defibrillator (ICD) recipients, the 2-year risk for VT/VF/death was 13% in ischemic women and 27% in ischemic men, but no significant differences were seen between non-ischemic males and females. The hazard ratio for VT/ VF/death in cardiac resynchronization therapy defibrillator versus ICD was 0.68 for females, compared with 0.86 for males.

Take Home Pearls: Women with ischemic cardiomyopathy appear to have a lower risk of arrhythmic events than men. More research is needed to further explore the nature of this relationship.

Assessing Primary AF Prevention with Statins in the Elderly

The Particulars: Statins have proven to be effective treatments for older patients with many types of cardiac conditions. However, the effectiveness of statin therapy as a primary prevention treatment for atrial fibrillation (AF) has not been well studied in elderly patients.

Data Breakdown: Taiwanese researchers conducted a study to determine if any comorbidity or CHADS2 score could predict the effectiveness of statin therapy on primary AF prevention in patients aged 65 and older. Risk of AF was reduced by 19% among statin therapy users when compared with non-users. The benefits of statin therapy did not appear to be affected by the presence or lack of any particular comorbidity. Statins were significantly effective in patients with a CHADS2 score of 2 or greater in most cases.

Take Home Pearl: Statin therapy appears to lower the risk of new-onset AF in elderly patients who have hypertension.

Looking at SDB in Patients Undergoing PCI

The Particulars: The association between sleep disordered breathing (SDB) and complex ventricular tachyarrhythmias in patients undergoing direct PCI for acute myocardial infarction (AMI) has not been well studied in previous research.

Data Breakdown: Investigators conducted overnight sleep studies between 3 and 7 days after primary PCI in patients with an AMI. An apnea-hypopneaindex score of 5 or higher was observed in 66% of patients. Non-sustained ventricular tachycardias (nsVT) were observed in 10.2% of patients in the study group. The incidence of nsVT was strongly associated with the severity of SDB.

Take Home Pearls: The prevalence of previously undiagnosed SDB appears to be high among patients admitted to the hospital with AMI. The risk for nsVT appears to increase as the severity of SDB worsens.

References

For more information on these studies and others that were presented at Heart Rhythm 2012, go to www.hrsonline.org/sessions.