Introduction/Hypothesis:
A 74-year-old gentleman presented with acute on chronic hypoxic respiratory failure. His medical comorbidities include, but are not limited to, right lower lobe adenocarcinoma s/p chemoradiation ( 60 Gy/30 fractions; last treatment 5/2022) followed by a 12-month course of immunotherapy with Durvalumab (Durvalumab 1500 mg every 28 days, last dose 5/2023), COPD (2L nasal cannula at baseline), hypertension, gastroesophageal reflux disease, and hypothyroidism.
Briefly, for one month, the patient experienced worsening dyspnea on exertion. CT chest showed right lower lobe consolidation/infiltrate with associated lymphadenopathy, concerning for treatment-associated pneumonitis (radiation- vs. ICI-associated).  Transthoracic echocardiography revealed normal left ventricle size and function (left ventricular ejection fraction 66%), new valvular diseases, and normal inferior vena cava size with normal collapsibility.  Subsequently, patient was initiated on prednisone 60 mg once daily.
One week later, the patient presented to the emergency department with increasing oxygen requirements (8L nasal cannula), leukocytosis of 20 with neutrophilia of 19, lactate of 8.4, and acute kidney injury. Electrocardiogram showed sinus tachycardia and nonspecific ST changes. CT chest showed stable right central consolidative opacities with architectural distortion favor to represent postradiation changes.  He was admitted to the ICU initiated on broad-spectrum antibiotics and mild pressor support.  The next morning, the patient significantly improved clinically and required 2 L nasal cannula.
Two days later, the patient acutely decompensated and developed flash pulmonary edema requiring BiPAP and diuresis.  Electrocardiogram showed normal sinus rhythm with more prominent T-wave inversions in the anterolateral leads. Troponins were elevated but stable (300-326-325). Repeat transthoracic echocardiography showed a newly depressed left ventricular ejection fraction of 31%, and akinesis of the mid and apical regions.  There was no evidence of left ventricular outflow tract obstruction. Cardiology was consulted for further management.

Methods
In order to help discern the etiology between stress-induced cardiomyopathy and ICI-associated myocarditis, cardiac magnetic resonance imaging was recommended.
Patient was initiated on beta blockade with bisoprolol and afterload reduction with losartan. Diuresis was continued.
Given significant apical akinesis, therapeutic anticoagulation to prophylactically prevent left ventricular thrombus formation was discussed.
Results
Cardiac MRI showed asymmetric left ventricle (basal septal hypertrophy 17 mm), no LVOT obstruction, globally reduced systolic function (LVEF 35%), and more pronounced regional wall motion abnormalities of the basal and mid antero- and inferolateral segments.
Pre-contrast T2 mapping shows globally elevated T2 values of approximately 71 ms.
Postcontrast images show no first-pass myocardial perfusion abnormalities. Delayed postcontrast images demonstrate patchy mid-myocardial late gadolinium enhancement involving the lateral and inferolateral wall in the mid-basal segments
Globally reduced RV systolic function (RVEF = 37%).
Conclusion
Cardiac MRI revealed globally reduced LV and RV systolic function, more pronounced in the areas with LGE. The LGE involving the lateral and inferolateral walls in the mid-basal segments, most compatible with a nonischemic pattern, which can be seen with ICI-associated myocarditis.
This case underscores the importance of cardiac MRI in distinguishing etiologies of left ventricular dysfunction, especially in the diagnosis of ICI-associated myocarditis.

**Introduction/Hypothesis:**
A 74-year-old gentleman presented with acute on chronic hypoxic respiratory failure. His medical comorbidities include, but are not limited to, right lower lobe adenocarcinoma s/p chemoradiation ( 60 Gy/30 fractions; last treatment 5/2022) followed by a 12-month course of immunotherapy with Durvalumab (Durvalumab 1500 mg every 28 days, last dose 5/2023), COPD (2L nasal cannula at baseline), hypertension, gastroesophageal reflux disease, and hypothyroidism.
Briefly, for one month, the patient experienced worsening dyspnea on exertion. CT chest showed right lower lobe consolidation/infiltrate with associated lymphadenopathy, concerning for treatment-associated pneumonitis (radiation- vs. ICI-associated).  Transthoracic echocardiography revealed normal left ventricle size and function (left ventricular ejection fraction 66%), new valvular diseases, and normal inferior vena cava size with normal collapsibility.  Subsequently, patient was initiated on prednisone 60 mg once daily.
One week later, the patient presented to the emergency department with increasing oxygen requirements (8L nasal cannula), leukocytosis of 20 with neutrophilia of 19, lactate of 8.4, and acute kidney injury. Electrocardiogram showed sinus tachycardia and nonspecific ST changes. CT chest showed stable right central consolidative opacities with architectural distortion favor to represent postradiation changes.  He was admitted to the ICU initiated on broad-spectrum antibiotics and mild pressor support.  The next morning, the patient significantly improved clinically and required 2 L nasal cannula.
Two days later, the patient acutely decompensated and developed flash pulmonary edema requiring BiPAP and diuresis.  Electrocardiogram showed normal sinus rhythm with more prominent T-wave inversions in the anterolateral leads. Troponins were elevated but stable (300-326-325). Repeat transthoracic echocardiography showed a newly depressed left ventricular ejection fraction of 31%, and akinesis of the mid and apical regions.  There was no evidence of left ventricular outflow tract obstruction. Cardiology was consulted for further management.

**Methods**
- In order to help discern the etiology between stress-induced cardiomyopathy and ICI-associated myocarditis, cardiac magnetic resonance imaging was recommended.
- Patient was initiated on beta blockade with bisoprolol and afterload reduction with losartan. Diuresis was continued.
- Given significant apical akinesis, therapeutic anticoagulation to prophylactically prevent left ventricular thrombus formation was discussed.

**Results**
- Cardiac MRI showed asymmetric left ventricle (basal septal hypertrophy 17 mm), no LVOT obstruction, globally reduced systolic function (LVEF 35%), and more pronounced regional wall motion abnormalities of the basal and mid antero- and inferolateral segments.
- Pre-contrast T2 mapping shows globally elevated T2 values of approximately 71 ms.
- Postcontrast images show no first-pass myocardial perfusion abnormalities. Delayed postcontrast images demonstrate patchy mid-myocardial late gadolinium enhancement involving the lateral and inferolateral wall in the mid-basal segments
- Globally reduced RV systolic function (RVEF = 37%).

**Conclusion**
Cardiac MRI revealed globally reduced LV and RV systolic function, more pronounced in the areas with LGE. The LGE involving the lateral and inferolateral walls in the mid-basal segments, most compatible with a nonischemic pattern, which can be seen with ICI-associated myocarditis.
This case underscores the importance of cardiac MRI in distinguishing etiologies of left ventricular dysfunction, especially in the diagnosis of ICI-associated myocarditis.

New-onset Heart Failure: ICI-associated myocarditis vs stress-induced cardiomyopathy