Demographics, Care Patterns, and Outcomes of Patients Admitted to Cardiac Intensive Care Units: The Critical Care Cardiology Trials Network Prospective North American Multicenter Registry of Cardiac Critical Illness

Abstract

Importance: Single-center and claims-based studies have described substantial changes in the landscape of care in the cardiac intensive care unit (CICU). Professional societies have recommended research to guide evidence-based CICU redesigns.

Objective: To characterize patients admitted to contemporary, advanced CICUs.

Design, setting, and participants: This study established the Critical Care Cardiology Trials Network (CCCTN), an investigator-initiated multicenter network of 16 advanced, tertiary CICUs in the United States and Canada. For 2 months in each CICU, data for consecutive admissions were submitted to the central data coordinating center (TIMI Study Group). The data were collected and analyzed between September 2017 and 2018.

Main outcomes and measures: Demographics, diagnoses, management, and outcomes.

Results: Of 3049 participants, 1132 (37.1%) were women, 797 (31.4%) were individuals of color, and the median age was 65 years (25th and 75th percentiles, 55-75 years). Between September 2017 and September 2018, 3310 admissions were included, among which 2557 (77.3%) were for primary cardiac problems, 337 (10.2%) for postprocedural care, 253 (7.7%) for mixed general and cardiac problems, and 163 (4.9%) for overflow from general medical ICUs. When restricted to the initial 2 months of medical CICU admissions for each site, the primary analysis population included 3049 admissions with a high burden of noncardiovascular comorbidities. The top 2 CICU admission diagnoses were acute coronary syndrome (969 [31.8%]) and heart failure (567 [18.6%]); however, the proportion of acute coronary syndrome was highly variable across centers (15%-57%). The primary indications for CICU care included respiratory insufficiency (814 [26.7%]), shock (643 [21.1%]), unstable arrhythmia (521 [17.1%]), and cardiac arrest (265 [8.7%]). Advanced CICU therapies or monitoring were required for 1776 patients (58.2%), including intravenous vasoactive medications (1105 [36.2%]), invasive hemodynamic monitoring (938 [30.8%]), and mechanical ventilation (652 [21.4%]). The overall CICU mortality rate was 8.3% (95% CI, 7.3%-9.3%). The CICU indications that were associated with the highest mortality rates were cardiac arrest (101 [38.1%]), cardiogenic shock (140 [30.6%]), and the need for renal replacement therapy (51 [34.5%]). Notably, patients admitted solely for postprocedural observation or frequent monitoring had a mortality rate of 0.2% to 0.4%.

Conclusions and relevance: In a contemporary network of tertiary care CICUs, respiratory failure and shock predominated indications for admission and carried a poor prognosis. While patterns of practice varied considerably between centers, a substantial, low-risk population was identified. Multicenter collaborative networks, such as the CCCTN, could be used to help redesign cardiac critical care and to test new therapeutic strategies.

Figure 1.. Category of Primary Reason for Admission to the Cardiac Intensive Care Unit (CICU) in the Overall Cohort

Analysis includes all CICU admissions for 2 months. CV indicates cardiovascular; ICU, intensive care unit.

Figure 2.. Primary Reason for Admission to the Cardiac Intensive Care Unit (CICU)

Analysis includes CICU admissions (N = 3049) from the primary analysis cohort, which excludes general medical intensive care unit overflow and admissions solely for postoperative management after cardiac surgery. Cardiogenic shock and cardiac arrest denote cases in which the etiology is not already captured by a primary cause^a (eg, acute coronary syndrome [ACS] leading to cardiogenic shock is captured as ACS and ventricular arrhythmia causing cardiac arrest is captured as VT/VF). CV indicates cardiovascular; HF, heart failure; STEMI, ST-elevation myocardial infarction.

Figure 3.. Frequency of Indication for Cardiac Intensive Care Unit (CICU) Admission and CICU Mortality by ICU Indications

A, Represents percentage of admissions according to intensive care unit (ICU) indication. B, The CICU mortality rate represents the proportion of patients with the relevant indication who died while in the CICU. For both panels, the only mutually exclusive categories for indication were postprocedural observation and the need for frequent monitoring or laboratory testing (N = 3049). IV indicates intravenous.

Figure 4.. Acute Intensive Care Therapies and Monitoring

Invasive hemodynamics refers to central venous or arterial monitoring, with pulmonary artery (PA) catheters (11%) representing a subset of central venous cannulation. ICU indicates intensive care unit; MV, mechanical ventilation; NIPPV, noninvasive positive pressure ventilation.