Marked QTc Reduction Immediately Following Direct Current Cardioversion of Atrial Fibrillation: Clinical Implications and Mechanisms.

BACKGROUND: The QTc in sinus rhythm (SR) following direct current cardioversion (DCCV) of atrial fibrillation (AF) is commonly used as a baseline QTc for patients who require initiation of antiarrhythmic drugs for rhythm control. Inaccurate baseline QTc may cause drug-induced torsades de pointes. OBJECTIVES: This study sought to assess time-dependent QTc changes following DCCV. METHODS: We prospectively assessed QTc changes with Bazett's QTc and Fridericia's QTc formulas in 65 patients following conversion of AF to SR. Among these 65 patients, 48 underwent DCCV and 17 spontaneously converted to SR. RESULTS: There was a large and statistically significant decrease in QTc in SR immediately following DCCV in 40 patients, which occurred with an abrupt reduction in heart rate postcardioversion. This finding excluded 8 patients with ventricular-paced QRS. The mean decrease from QTc in AF was 70.7 ± 37.2 milliseconds in the QTc interval for heart rate using Bazett's formula and 33.8 ± 17.9 milliseconds in the QTc interval for heart rate using Fridericia's formula at 1-minute post-DCCV. In 17 patients with spontaneous conversion from AF to SR, the QTc reduction was comparable to those in patients with DCCV. The QTc increased with time and reached a steady state at 5 minutes following conversion. Initiation of Class III drugs based on the "shortened" baseline QTc following DCCV was associated with drug-induced torsades de pointes. CONCLUSIONS: In patients with AF following conversion, regardless spontaneous or DCCV, the QTc shortened significantly with decreases in heart rate, likely via the mechanism of time-dependent rate adaption of ventricular repolarization. A steady-state QTc at 5-minutes following DCCV should be used as real baseline for guidance of pharmacotherapy in patients with AF.

Catheter-Directed Mechanical Thrombectomy in Massive Pulmonary Embolism With Cardiogenic Shock.

We discuss a patient who presented with cardiogenic shock secondary to massive pulmonary embolism and right ventricular failure. She was managed by a multidisciplinary heart team and treated with catheter-directed thrombectomy, followed by ProtekDuo (Tandem [Liva Nova], London, United Kingdom) heart percutaneous right ventricular support leading to complete recovery from this often fatal condition. (Level of Difficulty: Intermediate.).

Case report and systematic review of pulmonary embolism mimicking ST-elevation myocardial infarction.

BACKGROUND: To study trends in the clinical presentation, electrocardiograms, and diagnostic imaging in patients with pulmonary embolism presenting as ST segment elevation. METHODS: We performed a systematic literature search for all reported cases of pulmonary embolism mimicking ST-elevation myocardial infarction. Pre-specified data such as clinical presentation, electrocardiogram changes, transthoracic echocardiographic findings, cardiac biomarkers, diagnostic imaging, therapy, and outcomes were collected. RESULTS: We identified a total of 34 case reports. There were 23 males. Mean age of the population was 56.5 ± 15.5 years. Patients presented with dyspnea (76.4%), chest pain (63.6%), and tachycardia (71.4%). All patients presented with ST-elevations, with the most common location being in the anterior-septal distribution, lead V3 (74%), V2 (71%), V1 (62%) and V4 (47%). ST-segment elevations in the inferior distribution were present in lead II (12%), III (18%), and aVF (21%). Presentation was least likely in the lateral distribution. Troponin was elevated in 78.9% of cases. Right ventricular strain was the most common echocardiographic finding. Over 80% of patients had findings consistent with elevated right ventricular pressure, with 50% reported RV dilatation and 20% RV hypokinesis. The most commonly used imaging modality was contrast-enhanced pulmonary angiography. There was a greater incidence of bilateral compared to unilateral pulmonary emboli (72.4% vs. 10%). About 65% patients received anticoagulation and 36.3% were treated with thrombolytics. Forty-six percent of patients required intensive care and 18.7% intubation. Overall mortality was 25.8%. CONCLUSIONS: A review of the literature reveals that in patients presenting with pulmonary embolism, electrocardiogram findings of ST-segment elevations will occur predominantly in the anterior-septal distribution.