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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 1, January/February 2019
30
AFRICA
Methods
The primary study objective was to determine the in-hospital
and long-term (30-day and one-year) mortality rates of ACS
patients treated at the Aga Khan University Hospital, Nairobi
(AKUHN). Secondary objectives were to determine the rate of
in-hospital non-fatal events, specifically heart failure, recurrent
myocardial infarction (MI), need for repeat revascularisation,
stroke and major bleeding, and to determine the rate of
rehospitalisation in the first year owing to major adverse events
(recurrent MI, stroke and major bleeding).
This was a cross-sectional, retrospective review of chart
and electronic health records for all patients admitted with
ACS between 1 January 2012 and 31 December 2013. To
confirm our findings, and where chart data were ambiguous,
telephone interviews were conducted with the patients and
documented relatives to determine the long-term outcomes
following discharge.
Ethical approval was obtained from the Ethical and Scientific
ReviewCommittee of the AKUHN. Verbal consent was obtained
from the participants prior to initiating the telephone interview.
The study included patients who received a discharge diagnosis
of ACS and its subcategories: ST-elevation myocardial infarction
(STEMI), non-ST-elevation myocardial infarction (NSTEMI),
and unstable angina (UA) (ICD 10 codes I20.0, I21, I22,
respectively). Patients with suspected type 2 MI were excluded.
MI was defined by the third universal definition of MI;
15
major bleeding was defined as per the TIMI bleeding criteria,
16
and the diagnosis of stroke was based on the American Heart
Association/American Stroke Association updated definition.
17
Other outcome definitions were based on accepted definitions
used in cardiovascular trials.
18
Statistical analysis
IBM Statistical Package for Social Sciences (SPSS) version 21
was used to analyse the data. All patients were grouped into
either STEMI or non-ST-elevation ACS (NSTE-ACS, consisting
of NSTEMI or UA) for comparison of demographic and clinical
characteristics, and outcome variables of interest. Continuous
variables are expressed as mean
±
standard deviation and
comparisons between means were performed using independent
samples Student’s
t
-test. Categorical variables are expressed
as percentages, and comparisons between subgroups were
performed using Fisher’s exact test.
Survival analysis was performed using Kaplan–Meier
estimates. The duration from event to death was calculated for
patients who died. Patients were censored at the date of last
contact based on the medical records or on the date of the
telephone interview, whichever was latest.
Results
During the 24-month period, 230 patients were admitted with
ACS. Of these, 101 had a STEMI, 93 suffered an NSTEMI,
and 36 had UA. Demographic and clinical characteristics of the
patients are summarised in Table 1.
Fewer than 10% of patients presented within one hour of
symptom onset, while more than 35% took longer than 24 hours
to arrive at the hospital, some taking as long as two weeks (Fig.
1). Patients with STEMI tended to present earlier, compared to
those with NSTE-ACS, with 46.6 and 23.3% presenting within
six hours of symptom onset, respectively.
Of the 101 patients admitted with STEMI, 49 received
thrombolytic therapy while 19 patients underwent primary
percutaneous intervention (PCI). Thirty-three patients presented
outside the acute phase and did not receive acute reperfusion
therapies. The mean time to thrombolysis and PCI was 49 (
±
42)
and 137 (
±
63) minutes, respectively.
Target door-to-needle time for thrombolysis of 30 minutes
was met in 26 of the 49 patients thrombolysed (53.1%), and
door-to-balloon time of 90 minutes in five of the 19 patients
taken for primary PCI (26.3%).
One hundred and ninety-six of 230 (85.2%) patients
underwent coronary angiography. The left anterior descending
Table 1. Demographic and clinical characteristics of patients
Patient characteristics
STEMI
(
n
=
101 )
NSTE-ACS
(
n
=
129 )
p
-value
Age, years
58.7
±
13.8 61.9
±
12.0 0.063
Male gender, %
81.2
82.2
0.865
Diabetes, %
43.6
31.0
0.054
Hypertension, %
52.5
64.3
0.080
Smoker, %
22.8
23.3
1.0
Prior myocardial infarct, %
5.9
28.7
<
0.001
Creatinine, μmol/l
108.6
±
60.7 103.8
±
45.3 0.135
Creatinine clearance (Cockcroft–Gault),
ml/min/1.73 m
2
84.2
±
38.4 82.7
±
37.1 0.555
Total cholesterol, mmol/l
4.6
±
1.4
4.5
±
1.4 0.588
HDL, mmol/l
1.1
±
0.3
1.1
±
0.3 0.348
LDL, mmol/l
2.9
±
1.3
2.8
±
1.2 0.683
BMI, kg/m
2
27.6
±
4.1 28.1
±
5.1 0.188
Systolic BP, mmHg
127
±
28
140
±
24 0.128
Pulse rate per minute
88
±
19
79
±
17 0.021
Ethnicity
Black African, %
33.7
34.9
Caucasian, %
4.0
9.3
Asian Indian, %
62.4
55.8
STEMI, ST-elevation myocardial infarction, NSTE-ACS, non-ST-elevation
acute coronary syndrome; HDL, high-density lipoprotein cholesterol; LDL,
low-density lipoprotein cholesterol; BMI, body mass index.
Presentation
< 1
hour
1–3
hours
3–6
hours
6–12
hours
12–24
hours
> 24
hours
Percent
50
40
30
20
10
0
Diagnosis
STEMI
NSTE-ACS
Fig. 1.
Duration from symptom onset to presentation in
patients with acute coronary syndrome.