QTc interval on 24-hour holter monitor: To trust or not to trust?

INTRODUCTION: QT interval represents the ventricular depolarization and repolarization. Its accurate measurement is critical since prolonged QT can lead to sudden cardiac death. QT is affected by heart rate and is corrected to QTc via several formulae. QTc is commonly calculated on the ECG and not the 24-h Holter. METHODS: 100 patients presenting to our institution were evaluated by an ECG followed by a 24-h Holter. QTc measurement on both platforms using Bazett and Fridericia formulae was recorded and compared. RESULTS: Mean age was 14.09 years, with the majority being males. Mean heart rate was 125.87. In the ECG, the mean QTc interval via the Bazett formula was 0.40 s compared with 0.38 s using the Fridericia formula. The mean corrected QT via the Bazett formula was 0.45, 0.39, and 0.42 s for the shortest RR, the longest RR, and the average RR, respectively. In contrast to the Fridericia formula, the corrected QT interval was 0.40, 0.39, and 0.40 s for the shortest RR, the longest RR, and the average RR, respectively. Using the Bazett formula, the highest specificity was reached during the longest RR interval (92.2%), while the highest sensitivity was recorded during the shortest RR interval (40%). As for the Fridericiaformula, sensitivity always reached 0%, while the highest specificity was reached during the average RR interval. CONCLUSION: QTc measured during Holter ECG reached a high specificity regardless of RR interval using the Fridericia and during the longest and the average RR interval for the Bazett formula. The consistently low sensitivity reveals that Holter ECG should not be used to rule out prolonged QT.

Cardiac Tamponade Caused by Cutibacterium acnes: An Updated and Comprehensive Review of the Literature.

Bacterial pericarditis is a critical diagnosis caused by a wide range of organisms including Streptococcus pneumoniae and other anaerobic organisms like Cutibacterium acnes which has been gaining more importance as a causative organism. Cutibacterium species are Gram-positive microaerophilic rods that constitute part of the normal flora of skin and mucosal membranes. The incidence of pericarditis caused by this organism is underreported as it is often dismissed as a skin flora contaminant. However, if left untreated, Cutibacterium acnes can cause pericarditis with serious complications. In this paper, we present a comprehensive review of the literature regarding pericarditis caused by Cutibacterium acnes along with a case presentation from our institution. In our institution, a 20-year-old man with history of atrial septal defect presented with chest pain radiating to the back along with symptoms of upper respiratory tract infection including headaches and myalgia. Electrocardiogram was remarkable for diffuse low-voltage waves. Echocardiography revealed a large pericardial effusion with tamponade features. Pericardiocentesis drained 1.2 L of milky fluid. Pericardial fluid analysis grew Cutibacterium acnes after being cultured for 8 days. The patient received 3 weeks of IV penicillin followed by 3 weeks of oral amoxicillin along with nonsteroidal anti-inflammatory agents and colchicine with no recurrence. Pericarditis caused by Cutibacterium acnes requires a high clinical suspicion since isolation of this organism can be dismissed as a skin flora contaminant. Literature review reveals that this infection may be underdiagnosed and underreported. Prompt diagnosis may lead to timely initiation of antibiotics which can help prevent devastating complications like constrictive pericarditis. Prospective studies are needed to evaluate the true incidence and prevalence of this disease.