All patients eligible for inclusion in the study were treated with Non-invasive ventilation.

Noninvasive ventilation (NIV) was performed with a noninvasive ventilator (BiPAP Synchrony®, Respironics Inc., Murrysville, PA, USA).

The New York Heart Association (NYHA) Functional Classification provides a simple way of classifying the extent of heart failure.

Class I: Cardiac disease, but no symptoms and no limitation in ordinary physical activity, e.g. no shortness of breath when walking, climbing stairs etc.

Class II: Mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity.

Class III: Marked limitation in activity due to symptoms, even during less-than-ordinary activity, e.g. walking short distances (20-100 m). Comfortable only at rest.

Class IV: Severe limitations. Experiences symptoms even while at rest. Mostly bedbound patients.

The Killip classification is a system used in individuals with an acute myocardial infarction, in order to risk stratify them. Patients were ranked by Killip class in the following way:

Killip class I includes individuals with no clinical signs of heart failure. Killip class II includes individuals with rales or crackles in the lungs, an S3, and elevated jugular venous pressure.

Killip class III describes individuals with frank acute pulmonary edema. Killip class IV describes individuals in cardiogenic shock or hypotension (measured as systolic blood pressure lower than 90 mmHg), and evidence of peripheral vasoconstriction (oliguria, cyanosis or sweating).