Indications and Effectiveness of ICD for Primary and Secondary Prevention in Patients Admitted in Ahvaz Imam Khomeini Hospital since 2017.

Background: Implantable cardioverter-defibrillators (ICDs) have been established for primary and secondary prevention of fatal arrhythmias and effectively reduce the rate of sudden cardiac death (SCD). This study aims to evaluate the indications and effectiveness of ICD for primary and secondary prevention of SCD. Materials and Methods: This retrospective study was conducted on 229 patients (136 for primary and 93 for secondary prevention) with ICD implantations in Imam Khomeini Hospital, Ahvaz, between 2017 and 2020. The incidence of arrhythmic events after implantation of ICDs was saved in electrograms, and the performed treatments (antitachycardia pacing (ATP)/shock) were recorded from the device memory. Results: The indications for ICD implantation in primary and secondary prevention were different (P < 0.0001). The most common cause of ICD implantation for primary prevention was ischemic cardiomyopathy (ICMP, 90.4%) and for secondary prevention was ICMP (58.1%) followed by dilated cardiomyopathy (31.2%). During ICD implantation, 54 patients (39.7%) with ICD implantation for primary prevention and 50 patients (53.8%) for secondary prevention had arrhythmia (P = 0.043). The rate of appropriate therapies in patients with secondary prevention was higher than the primary prevention (57.9% vs. 42.1%), while the rate of inappropriate treatments in patients with primary prevention indication was more than the secondary prevention (63% vs. 37%) (P = 0.060). Conclusions: ICMP was the main cause of ICD implantation for the prevention of SCD in both groups. At follow-up, the high prevalence of appropriate ICD therapy was observed in both groups, and this risk was slightly higher in the secondary prevention group.

Comparison of trinitroglycerin and adenosine as provocative agents for head-up tilt test in patients with unexplained syncope: a semi-crossover randomized clinical trial with prospective follow-up.

PURPOSE: Head-up tilt test (HUTT) is a reasonable diagnostic evaluation for patients with suspected vasovagal syncope; however, its lengthy duration is a remarkable limitation. Although adenosine (AD), as an alternative provocative agent, is a promising option for tackling this shortcoming, it received little appreciation in the literature. We aimed to compare the efficacy and the time to elicit a positive response to HUTT for sublingual trinitroglycerin (TNG) and intravenous AD. Furthermore, we evaluated patients' outcomes in the follow-up. METHODS: Patients with a chief complaint of transient loss of consciousness (TLOC) were evaluated. We randomized patients with the diagnosis of unexplained syncope after diagnostic evaluations, to undergo TNG-augmented HUTT or AD-augmented HUTT. They were crossed over to receive the other medication in case of negative response to the test. In the follow-up, we evaluated traumatic and non-traumatic TLOCs, hospitalization due to syncope, and death in patients. RESULTS: We randomized 132 patients (41.70 ± 19.37 years, 52.3% female) to receive TNG (n = 66) or AD (n = 66). Respectively, the positivity rate of TNG and AD for the first and the crossover-HUTT was 31.1% and 26.7%, and 20.5% and 26.2% with no statistically significant differences in both tests (P ˃ 0.50). The time to positive response was significantly shorter for AD than TNG (P < 0.001). In the follow-up, re-admission was significantly more prevalent in HUTT-negative patients compared to HUTT-positive patients (P = 0.04). CONCLUSIONS: We found that diagnostic yield of TNG and AD in HUTT is comparable, while AD acts 4 times faster than TNG in evoking a vasovagal response.