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Acute myocarditis is a rare complication of mRNA-based COVID-19 vaccination. Little is known about the natural history of this complication.

Magnetic resonance imaging (MRI) is often considered the gold-standard test for characterizing cardiac as well as noncardiac structure and function. However, many patients with cardiac implantable electronic devices (CIEDs) and/or severe renal dysfunction are unable to undergo this test because of safety concerns. In the past 10 years, newer-generation CIEDs and gadolinium-based contrast agents (GBCAs) as well as coordinated care between imaging and heart rhythm device teams have mitigated risk to patients and improved access to MRI at many hospitals. The purpose of this statement is to review published data on safety of MRI in patients with conditional and nonconditional CIEDs in addition to patient risks from older and newer GBCAs. This statement was developed through multidisciplinary collaboration of pan-Canadian experts after a relevant and independent literature search by the Canadian Agency for Drugs and Technologies in Health. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations include: (1) the development of standardized protocols for patients with a CIED undergoing MRI; (2) patients with MRI nonconditional pacemakers and pacemaker dependency should be programmed to asynchronous mode and those with MRI nonconditional transvenous defibrillators should have tachycardia therapies turned off during the scan; and (3) macrocyclic or newer linear GBCAs should be used in preference to older GBCAs because of their better safety profile in patients at higher risk of nephrogenic systemic fibrosis.

Background: Pulse pressure is a readily available vital sign that has been shown to independently predict outcomes in several cardiovascular disease states. We investigated the prognostic significance of pulse pressure (PP) and systolic blood pressure (SBP) among patients with acute coronary syndromes (ACS).Methods: A total of 14,514 patients with ACS in the prospective, multicentre Global Registry of Acute Coronary Events (GRACE), expanded GRACE (GRACE-2) and Canadian Registry of Acute Coronary Events (CANRACE) were stratified by initial PP on presentation. Patient characteristics and in-hospital outcomes were compared by PP quartiles and the independent prognostic significance of PP for in-hospital mortality was quantified. We compared the discriminative ability (c-statistic) of models incorporating either PP or SBP.Results: Patients with higher PPs were older, more frequently female and had higher prevalence rates of conventional cardiovascular risk factors (all p< 0.01). Lower PP was associated with ST-segment elevation myocardial infarction presentation, higher GRACE risk scores and higher rates of adverse in-hospital outcomes (p< 0.001). PP was strongly correlated with SBP (Pearson’s correlation coefficient = 0.79, p< 0.001). After adjustment for other GRACE risk model predictors, lower PP was independently associated with in-hospital mortality (first vs. fourth quartile [reference]: adjusted odds ratio 2.57, 95% confidence interval 1.80–3.67). The c-statistic was slightly higher for the multivariable model incorporating SBP as compared to the model with PP (0.868 vs. 0.864, respectively, p= 0.028) for in-hospital mortality.Conclusion: Higher presenting PP is associated with increased age and more prevalent cardiovascular risk factors, whereas patients with lower PP present with worse clinical characteristics and in-hospital outcomes. Lower PP is an independent adverse prognosticator in ACS. However, PP did not improve the discriminatory performance of the GRACE risk score compared with SBP.

Introduction:Acute myocarditis is a rare complication of mRNA-based COVID-19 vaccination. The natural history and clinical sequalae of this complication are of critical importance to estimate the impact on population health.Objective:To study the impact of COVID-19 vaccine associated myocarditis on convalescent myocardial health, symptoms, and clinical outcomes.Methods:This study was performed at two tertiary care hospitals. Baseline and convalescent (≥3 month) CMR imaging was performed for 20 consecutive patients meeting Updated Lake Louise Criteria for acute myocarditis within 10 days of mRNA-based vaccination and with no evidenceof active viral infection. Global and segmental CMR-based markers of myocardial injury were studied at baseline and convalescence, inclusive of chamber volumetry, LV ejection fraction (LVEF), LV mass, T1 and T2 mapping, late gadolinium enhancement (LGE) imaging, and extracellular volume (ECV) fraction. Major clinical outcomes were captured.Results:The median age was 23.1 years (range 18-39 years) with 17 (85%) being male. Convalescent CMR evaluations were performed at a median (IQR) of 3.7 (3.3-6.2) months. Five patients (25%) had a baseline LVEF <50%. All patients showed abnormal LGE inclusive of a sub-epicardial pattern with a mean LGE burden of 8.6+/-5.3% LV mass using a >5SD of reference threshold. At follow-up, a mean 3% absolute improvement in LVEF was observed, accompanied by a 7% reduction in LVEDV and 5% reduction in LV mass (all p<0.015). Global LGE volume reduced by 66% (p<0.001). Absolute reductions in global T2, native T1, and ECV of 2.1msec, 58msec, and 2.9%, respectively were documented (all p≤0.001). All patients with LVEF <50% at baseline recovered above this threshold. However, 18 (90%) patients showed persistence of LGE at follow-up with 15% having a burden >5% of the LV mass. No patient experienced major clinical outcomes.Conclusion:COVID-19 mRNA vaccine associated myocarditis shows rapid improvement in CMR-based markers of tissue edema, contractile function, and LGE, and was not associated with adverse events at intermediate range follow-up. However, convalescent fibrosis was commonly observed, justifying ongoing need for clinical surveillance in this population.

Introduction:The respective value of different late gadolinium enhancement (LGE) phenotypes in patients with suspected infiltrative cardiomyopathy remains uncertain.Methods:In a large cohort of patients referred for suspected infiltrative cardiomyopathy, we evaluated respective associations between the dominant LGE phenotype and the composite endpoint of heart failure hospitalization, survived cardiac arrest or death. Kaplan-Meier survival curves were executed for six pre-defined LGE phenotypes. Multivariable analysis was performed to assess their independent association with the composite outcome, adjusted for relevant confounders. Final diagnosis was adjudicated using standardized disease-specific criteria.Results:588 patients (68% male, median age 70 years, mean LVEF 54.7±12.7%) were studied. Of these patients, 139 (24%) were confirmed to have cardiac amyloidosis (CA) (81 [58%] transthyretin, 54 [39%] light chain and 4 [3%] undifferentiated) by objective non-CMR diagnostic criteria. Any LGE was present in 394 patients (67%) with the dominant phenotype being diffuse in 137 (23%), mid-wall patchy in 118 (20%), ischemic in 55 (9.4%), subepicardial in 18 (3.1%), mid-wall striae in 8 (1.4%), and RV insertion site in 58 (9.9%). The sensitivity and specificity of diffuse LGE for CA was 86% and 96%, respectively. Over a median 855 (IQR 372, 1542) days, 239 (41%) experienced the primary outcome. Unadjusted survival curves for each LGE phenotype are shown in the Figure. Following adjustment, diffuse (HR 2.30, p<0.001), mid-wall patchy (HR 1.52, p=0.040) and ischemic LGE (HR 1.78, p=0.023) remained independently associated (Figure).Conclusions:In patients referred for suspected infiltrative cardiomyopathy, diffuse, mid-wall patchy and ischemic patterns all showed independent prognostic value. We confirm that diffuse LGE pattern reliably identifies CA patients with high sensitivity and specificity while delivering strong prognostic value.