A total of 1599 patients were included in the study. Results from the MCA show that two factors explain 62% of the variability in the data. Figure 1 shows the maps created by the first and second factors. The horizontal axis represents the first factor and the vertical axis the second factor. Variables well represented in the first factor were hypertension, anemia, toxic habits and drugs, atrial arrhythmia, congestive HF, renal disease, atrial fibrillation, sinus rhythm, edemas, EF, type of HF and NYHA functional class. The following categories were related to the positive side (right): having hypertension, having anemia, not having toxic habits, having congestive HF and renal disease, having neither atrial fibrillation nor sinus rhythm as precipitating factors, having edema as a symptom, having non-specified EF, BUN≥17.5 mg/dl, being a chronic patient with different follow-ups and being NYHA class IV. In contrast, categories on the negative side (left) were: having neither hypertension nor anemia, having toxic habits, having neither congestive HF nor renal disease, having atrial fibrillation or sinus rhythm as precipitating factors, not having edema, and having non-reduced EF, BUN<17.5 mg/dl, de novo HF and NYHA class I. This axis was defined as “Duration of HF”, from de novo (left side of the graph) to chronic >5 years (right side of the graph). In addition, the relative position of the outcomes on the graph shows that deaths up to 1 year, as well as readmissions and revisits to ED up to 1 year were well represented by this factor. Positive responses were located on the right side of the axis and negative responses on the left side.
Variables well represented in the second factor were: gender, age, coronary disease, myocardial infarction, atrial fibrillation and EF. Being female, aged >80 years, having neither coronary disease nor myocardial infarction and having atrial fibrillation were the categories related to the positive part (top), whereas being male, aged ≤ 80 years, having coronary disease or myocardial infarction and reduced EF and not having atrial fibrillation were related to the lower part of the graph (bottom). Therefore, this axis was interpreted as “Cardiovascular comorbidity”. EF was well represented in both factors: preserved (left part) and not available EF (right part) was well represented in the first factor whereas reduced EF was well represented in the bottom part of the second factor.
After applying CA to these results, three subtypes of AHF patient were identified (Figure 2). Group C had the most severe AHF and group B the least severe, in terms of mortality. Patients are represented in Figure 1 using different colors for these three subtypes. Figure 3 shows the two-dimensional distribution created by plotting the first and second components. The relative positions of the three outcome variables are projected onto the graph. The right side of the graph contains the most severe outcomes: deaths, readmissions, and revisits to ED.
Table 1 summarizes the data collected upon arrival at the ED for all patients and across the three subtypes of AHF as a function of the classification of their HF. Statistically significant differences between subtypes were observed in duration of HF, EF, NYHA functional class, etiology, presentation at the ED, precipitants and signs and symptoms of congestion. They also differed in age, gender, comorbidities, laboratory signs and health service use. (Table 2)
Table 1
Distribution of the main variables related to the classifications of heart failure
|
Total
|
Groups
|
p-value
|
|
|
A
N (%)
|
B
N (%)
|
C
N (%)
|
|
Total
|
1599
|
377 (23.58)
|
597 (37.34)
|
625 (39.09)
|
|
Duration of HF*
|
|
bc
|
ac
|
ab
|
<0.0001
|
De novo
|
646 (40.40)
|
69 (18.30)
|
508 (85.09)
|
69 (11.04)
|
|
Chronic, 0 years
|
62 (3.88)
|
22 (5.84)
|
6 (1.01)
|
34 (5.44)
|
|
Chronic, 1 year
|
273 (17.07)
|
99 (26.26)
|
27 (4.52)
|
147 (23.52)
|
|
Chronic, 1-5 years
|
407 (25.45)
|
91 (24.14)
|
43 (7.20)
|
273 (43.68)
|
|
Chronic, >5 years
|
211 (13.20)
|
96 (25.46)
|
13 (2.18)
|
102 (16.32)
|
|
Ejection fraction*
|
|
bc
|
ac
|
ab
|
<0.0001
|
Preserved
|
547 (34.21)
|
78 (20.69)
|
279 (46.73)
|
190 (30.40)
|
|
Reduced
|
232 (14.51)
|
69 (18.30)
|
148 (24.79)
|
15 (2.40)
|
|
Not known
|
820 (51.28)
|
230 (61.01)
|
170 (28.48)
|
420 (67.20)
|
|
NYHA class*
|
|
b
|
ac
|
b
|
<0.0001
|
I
|
189 (11.82)
|
26 (6.90)
|
135 (22.61)
|
28 (4.48)
|
|
II
|
429 (26.83)
|
88 (23.34)
|
177 (29.65)
|
164 (26.24)
|
|
III
|
541 (33.83)
|
127 (33.69)
|
183 (30.65)
|
231 (36.96)
|
|
IV
|
440 (27.52)
|
136 (36.07)
|
102 (17.09)
|
202 (32.32)
|
|
Etiology
|
|
|
|
|
|
Coronary disease *
|
407 (25.45)
|
268 (71.09)bc
|
93 (15.58)ac
|
46 (7.36)ab
|
<0.0001
|
High arterial blood pressure
|
613 (38.34)
|
126 (33.42)c
|
202 (33.84)c
|
285 (45.60)ab
|
<0.0001
|
Cardiomyopathy
|
387 (24.20)
|
101 (26.79)c
|
165 (27.64)c
|
121 (19.36)ab
|
0.0014
|
Valvular or congenital disease
|
388 (24.27)
|
62 (16.45)c
|
129 (21.61)c
|
197 (31.52)ab
|
<0.0001
|
Arrhythmia
|
315 (19.70)
|
43 (11.41)bc
|
161 (26.97)ac
|
111 (17.76)ab
|
<0.0001
|
Toxic habits and drugs*
|
31 (1.94)
|
3 (0.80)b
|
27 (4.52)ac
|
1 (0.16)b
|
<0.0001
|
Primary right ventricular failure
|
58 (3.63)
|
8 (2.12)c
|
14 (2.35)c
|
36 (5.77)ab
|
0.0012
|
Presentation at the emergency department
|
|
|
|
|
|
Systolic blood pressure
|
|
b
|
ac
|
b
|
0.0069
|
Low <90 mmHg
|
24 (1.52)
|
8 (2.14)
|
3 (0.51)
|
13 (2.11)
|
|
Normal ≥ 90 mmHg-≤140 mmHg
|
814 (51.68)
|
214 (57.37)
|
288 (49.23)
|
312 (50.57)
|
|
Elevated >140 mmHg
|
737 (46.79)
|
151 (40.48)
|
294 (50.26)
|
292 (47.33)
|
|
Precipitants
|
|
|
|
|
|
Acute myocardial infarction
|
20 (1.25)
|
9 (2.39)c
|
9 (1.51)
|
2 (0.32)a
|
0.0133
|
Hypertension
|
94 (5.88)
|
19 (5.04)
|
39 (6.53)
|
36 (5.76)
|
0.6198
|
Concurrent diseases
|
152 (9.51)
|
50 (13.26)b
|
44 (7.37)a
|
58 (9.28)
|
0.0092
|
Atrial fibrillation*
|
270 (16.89)
|
15 (3.98)bc
|
168 (28.14)ac
|
87 (13.92)ab
|
<0.0001
|
Other arrhythmias*
|
60 (3.75)
|
6 (1.59)b
|
38 (6.37)ac
|
16 (2.56)b
|
<0.0001
|
Signs and symptoms of congestion
|
|
|
|
|
|
Edema*
|
904 (56.54)
|
235 (62.33)b
|
284 (47.57)ac
|
385 (61.60)b
|
<0.0001
|
Rales
|
1167 (73.49)
|
287 (76.74)
|
417 (69.97)
|
463 (74.92)
|
0.0393
|
Oliguria
|
331 (20.91)
|
84 (22.34)b
|
90 (15.23)ac
|
157 (25.49)b
|
<0.0001
|
*Illustrative variables
|
Table 2
Differences between the three groups identified from the MCA and the CA, with respect to the active variables of the MCA and some others.
|
Total
|
Group
|
p-value
|
|
|
A
N (%)
|
B
N (%)
|
C
N (%)
|
|
Total
|
1599
|
377 (23.58)
|
597 (37.34)
|
625 (39.09)
|
|
Age (>80 years)*
|
781 (48.84)
|
152 (40.32)c
|
223 (37.35)c
|
406 (64.96)ab
|
<0.0001
|
Gender (Female)*
|
805 (50.34)
|
88 (23.34)bc
|
291 (48.74)ac
|
426 (68.16)ab
|
<0.0001
|
Comorbidities
|
|
|
|
|
|
Charlson index†
|
2 [1–3]
|
3 [2–5]bc
|
1 [0-2]ac
|
2 [1–3]ab
|
<0.0001
|
Myocardial infarction*
|
271 (16.95)
|
203 (53.85)cb
|
47 (7.87)ac
|
21 (3.36)ab
|
<0.0001
|
Congestive heart failure*
|
945 (59.10)
|
301 (79.84)b
|
115 (19.26)ac
|
529 (84.64)b
|
<0.0001
|
Peripheral vascular disease*
|
243 (15.20)
|
120 (31.83)cb
|
63 (10.55)a
|
60 (9.60)a
|
<0.0001
|
Peptic ulcer
|
120 (7.50)
|
38 (10.08)b
|
34 (5.70)a
|
48 (7.68)
|
0.0399
|
Diabetes with organ damage
|
126 (7.88)
|
52 (13.79)cb
|
34 (5.70)a
|
40 (6.40)a
|
<0.0001
|
Malignant tumor
|
189 (11.82)
|
57 (15.12)b
|
56 (9.38)a
|
76 (12.16)
|
0.0245
|
Moderate or severe kidney disease*
|
132 (8.26)
|
89 (23.61)cb
|
18 (3.02)a
|
25 (4.00)a
|
<0.0001
|
Hypertension*
|
1295(80.99)
|
316 (83.82)b
|
425 (71.19)ac
|
554 (88.64)b
|
<0.0001
|
Auricular arrhythmia *
|
959 (59.97)
|
188 (49.87)c
|
262 (43.89)c
|
509 (81.44)ab
|
<0.0001
|
Diabetes
|
624 (39.02)
|
178 (47.21)b
|
195 (32.66)ac
|
251 (40.16)b
|
<0.0001
|
Chronic obstructive pulmonary disease
|
305 (19.10)
|
94 (25.00)cb
|
99 (16.61)a
|
112 (17.92)a
|
0.0033
|
Depression
|
159 (9.94)
|
24 (6.37)c
|
48 (8.04)c
|
87 (13.92)ab
|
<0.0001
|
Smoking*
|
113 (7.07)
|
26 (6.90)cb
|
80 (13.40)ac
|
7 (1.12)ab
|
<0.0001
|
Anemia*
|
471 (29.46)
|
169 (44.83)cb
|
70 (11.73)ac
|
232 (37.12)ab
|
<0.0001
|
Laboratory test results
|
|
|
|
|
|
Low hemoglobin*
(12 women, 13 men)
|
851 (53.22)
|
284 (75.33)cb
|
203 (34.00)ac
|
364 (58.24)ab
|
<0.0001
|
Low sodium (<135 mEq/L)
|
221 (13.86)
|
61 (16.18)b
|
58 (9.73)ac
|
102 (16.40)b
|
0.0011
|
High BUN (≥17.5 mg/dl)*
|
293 (18.32)
|
124 (32.89)cb
|
41 (6.87)ac
|
128 (20.48)ab
|
<0.0001
|
High blood glucose (≥173.5 mg/dL)
|
312 (19.61)
|
89 (23.73)cb
|
120 (20.17)a
|
103 (16.59)a
|
0.0206
|
Potassium*
|
4.48 (1.61)
|
4.66 (2.07)cb
|
4.48 (1.93)a
|
4.37 (0.61)a
|
<0.0001
|
Troponin†
|
25 [12-45]
|
31 [15-53]b
|
19 [9-40]ac
|
29 [14-42]b
|
0.0003
|
Nt-proBNP (x1000)†
|
3.85 [2.02-7.72]
|
5.81 [2.94-11.06]cb
|
3.37 [1.75-5.45]a
|
3.80 [2.02-8.49]a
|
<0.0001
|
Health service use
|
|
|
|
|
|
Previous admission (yes)
|
564 (35.52)
|
212 (56.38)b
|
36 (6.04)ac
|
316 (51.30)b
|
<0.0001
|
Previous emergency department attendance (yes)
|
311 (19.62)
|
101 (27.01)b
|
17 (2.85)ac
|
193 (31.38)b
|
<0.0001
|
*Illustrative variables
†Data are expressed as medium [interquartile range]
|
The percentage of patients with a de novo diagnosis was higher in group B than in the rest of the groups, while the percentage of patients in whom HF was diagnosed more than 5 years earlier was higher in group A. There were significant differences between groups A and C in etiology: group A patients were more likely to have coronary disease or cardiomyopathy, and acute myocardial infraction as a precipitant, whereas hypertension, valve disease and right ventricular HF were the most common etiologies in group C. Further, the rates of arrhythmia as an etiology and toxic habits were higher in group B than in the other groups. The median of the Charlson comorbidity index was highest in group A.
Compared to the other groups, a reduced EF was more common in group B, and the percentage of NYHA class I patients was the highest in this group while the percentage of patients with hypotension at arrival at the ED was the lowest. Further, in group B, the percentage of patients with atrial fibrillation and other arrhythmias was higher and congestion was less common. (Table 1)
Regarding other variables (Table 2), the percentages of females and patients older than 80 years were highest in group C. Group A had the highest scores in the Charlson comorbidity index and the highest percentages of patients with low levels of hemoglobin and high levels of BUN and potassium and Nt-proBNP.
Associations between subtypes and outcomes are shown in Table 3. Group B was the less likely to present poor outcomes during the first year after the index episode. The distribution of patients across the subtypes was significantly associated with the five outcomes (p<0.001).
Table 3
Distribution of the outcomes, by subtype
|
Total
|
Group
|
p-value
|
|
|
A
N (%)
|
B
N (%)
|
C
N (%)
|
|
Total
|
1599
|
377 (23.58)
|
597 (37.34)
|
625 (39.09)
|
|
2-month mortality
|
123 (7.69)
|
39 (10.34)b
|
28 (4.69)ac
|
56 (8.96)b
|
0.0017
|
1-year readmission
|
857 (53.60)
|
229 (60.74)b
|
256 (42.88)ac
|
372 (59.52)b
|
<0.0001
|
1-year revisits to emergency department
|
453 (28.33)
|
130 (34.48)b
|
126 (21.11)ac
|
197 (31.52)b
|
<0.0001
|
1-year mortality
|
372 (23.57)
|
120 (32.26)b
|
95 (16.05)ac
|
157 (25.57)b
|
<0.0001
|
Group B were those who showed the greatest improvement in total and physical MLWHF scores and significant differences were detected between them and group C. (Figure4)