Clinical Research Directory

Do QT-Prolonging Drugs Cause Major Adverse Cardiac Events in Hospitalized Adults?

There are 28 non-cardiology medications from multiple families costing more than $13 billion annually in Canada, categorized as 'Known' QT-prolonging medications (QTPmeds) based on very low levels of evidence. The association between many commonly used medications listed as known QTPmeds and actual major adverse cardiac events (MACE) is weak. Meanwhile, QTPmeds-related warnings are ubiquitous in every healthcare setting, triggering 'hard stop' disruption millions of times per day to front line clinicians. Poor quality medication safety alerts are increasingly recognized as a source of inferior patient care and provider burnout which detracts from healthcare sustainability. In this study, anonymized hospital electronic medical record data from more than 990,000 adult patients across Ontario will be used to compare patients who experience MACE with those who do not, measuring their real-time exposure to QT-prolonging drugs. Additionally, machine-learning techniques will also be used to find which patient or treatment factors best predict risk. The objectives of this study are to 1) Investigate whether exposure to one or more 'Known' QTPmed is associated with an increased risk of MACE after adjusting for confounders; and 2) Identify predictors and their relative importance for QTPmeds-associated MACE. In summary, QT-prolonging medications have the potential to cause very serious adverse events, including death. However, it is not sufficiently clear which patients under which circumstances suffer events, or when is QT prolongation a useful surrogate marker for harm. Meanwhile, ubiquitous medication alerts related to QT-prolonging medications are at best imprecise and at worst, misleading, costly and potentially dangerous. Now that data resources are available with the data elements, structure and sample size required to rigorously assess this association, this study will address this question to improve patient safety, provider satisfaction and the cost-effectiveness of care.

Study Evaluating Dexmedetomidine in the Acute Treatment of Electrical Storm

The objective of this study is to determine if there is a meaningful benefit to using the sedative medication dexmedetomidine in the acute treatment of patients with recurrent ventricular arrhythmias, known as electrical storm. This will be a multi-centre, double-blinded, placebo-controlled, randomized trial. Patients with electrical storm will be randomized to receive 48 to 72 hours of dexmedetomidine or placebo as part of their initial treatment in an intensive care unit.

PRIMARY Ancillary Substudy

The PRIMARY trial (NCT05051033), which compares mitral valve repair (MVr) to transcatheter-edge-to-edge-repair (TEER), offers a platform for conducting mechanistic studies to develop early insights into the pathophysiological processes by which mitral valve prolapse (MVP) can impact left ventricular (LV) myocardial structure and function, and, thereby, predispose to arrhythmias and sudden death. Such insights are key to identifying interventions to reduce the long-term sequelae of heart failure (HF) and arrhythmias, as well as delineate optimal therapeutic approaches for different patient sub-groups.

Transcutaneous Vagus Nerve Stimulation for Ventricular Arrhythmias

Ventricular arrhythmias are abnormal heart rhythms that arise from the bottom chambers of the heart. They can cause debilitating symptoms when they occur intermittently (these are called premature ventricular ectopics or PVCs) and can be life-threatening when they occur continuously (called ventricular tachycardia or VT). These are the most common causes of sudden cardiac death, especially in patients with pre-existing heart disease. They can be a result of overactivation of the sympathetic nervous system, and in extreme circumstances, surgery to cut the nerve may be needed. A novel approach to target this nervous system using a transcutaneous electrical nerve stimulator (TENS) machine has successfully treated arrhythmias that come from the top chambers of the heart (atrial fibrillation). An ear clip is applied for an hour per day connected to a device (smaller than a phone) that can activate the parasympathetic nervous system (that counteracts the sympathetic nervous system). This is called Low-Level Tragus Stimulation (LLTS). Because it has been used for epilepsy for decades, we have evidence of a very high safety profile and tolerability. We plan to enrol 72 patients, 34 with many PVCs and 38 with VT, and randomise them to either first receive LLTS or first receive sham treatment (this will appear the same to the patient and researchers but without any meaningful vibrations being emitted in the sham group). Each patient will then swap over to the other treatment. We will compare whether the LLTS reduces the amount of ventricular arrhythmias during compared to the amount during the sham treatment period. We will use Holter monitors to measure the amount of PVCs after each period in the PVC group. VT patients have an implantable defibrillator that continuously monitors for VT episodes in this group. We will only enrol adults who can give informed consent, and study participation will not interfere with a patient's clinical treatment.

Ultra High Resolution CT to Assess Role of Intramyocardial Fat and Delayed Enhancement in Ventricular Arrhythmogenesis

This research is being done to determine how well cardiac computed tomography (CT) scanning measures of fat within the heart can predict abnormal heart rhythms and how well cardiac CT can measure scar within the heart versus cardiac magnetic resonance imaging (MRI). * People who have been enrolled in PROSe-ICD (NA\_00045142) and Reynolds (NA\_00037404) studies may join * The procedures, tests, drugs or devices that are part of this research and will be paid for by the study

Evaluation of Electrocardiographic Measurements by High Density Electrode ECG

Cardiac electrical activity is detected on the body surface with conventional electrocardiography involving 12 leads (ECG 12). A limitation of the current ECG technique is that recordings are obtained from only 6 independent precordial leads pairs ; which may miss cardiac potentials from spatially limited regions. More extensive sampling of the body surface may contribute to additional clinical information. The present study investigates the additional sensitivity of ECG using 128 body surface leads (High Density (HD) ECG) in measuring global or regional cardiac activity.

Hybrid Score to Predict OTVA-SOO in Patients with Wide Basal QRS

Outflow tract ventricular arrhythmia (OTVA) is the most common type of ventricular arrhythmia, and catheter ablation (CA) is the primary treatment option for patients experiencing symptoms. Accurately identifying the origin site of OTVA is essential for effective catheter ablation, minimizing procedural risks, and enhancing treatment success. However, most studies that developed algorithms or scoring systems for distinguishing OTVA origins excluded participants with structural heart disease and those with paced rhythms from their study groups. A recent prospective evaluation of a hybrid score (HS) that integrates both clinical and ECG data to predict OTVA-SOO, including patients with cardiac implantable electronic devices and those with structural heart disease in our study. The presented study aimed to assess the effectiveness of the previously described hybrid algorithm in predicting OTVA-SOO in a patient population characterized by a wide basal QRS due to intraventricular conduction defects or paced rhythms. The Hybrid Score The Hybrid Score (HS), involves a sum of points based on clinical and ECG characteristics. Points are assigned as follows: one point each for being over 50 years old, male, and having arterial hypertension. ECG-based points are allocated according to QRS transition: 3 points for a transition in V1, 2 points for V2, 1 point for V3 if the R-wave in V3 is greater than 1 mV; 1 point is subtracted if V3 has an R-wave less than 1 mV, and further deductions or additions apply for transitions up to V6. A score ≤ 1 suggests an RVOT origin, whereas ≥ 2 suggests an LVOT origin. ECGs were recorded with a standard configuration at a 25 mm/s sweep speed. Premature Ventricular Contraction (PVC) Ablation Activation mapping of spontaneous OTVAs was conducted. The procedure aimed to abolish spontaneous OTVAs, with the site of ablation marking the site of origin (SOO). Collected data * Patient Information and Consent (procedure must be done within 60 days of consent) * Demographics (age, gender, etc.) * Vital signs (length, weight, etc.) * Medical history, including cardiovascular risk factors, cardiomyopathy and drugs * ECG data * Echocardiographic data (left ventricular ejection fraction and left ventricular end-diastolic diameter) * Procedure data (number of radiofrequency applications, site of effective ablation, total radiofrequency time, total fluoro time, points mapping, procedure time) * Adverse Events

Scandinavian Multicenter Study to Advance Risk Stratification in Heart Disease- Ventricular Arrhythmias

The purpose of this study is to identify markers of increased risk for incident ventricular arrhythmias and cardiovascular events in patients already being treated with an implantable cardioverter-defibrillator (ICD) by exploring patient history and clinical findings, biological markers, ECG markers, and echocardiographic markers.