Impact of Obesity on Microvascular Obstruction and Area at Risk in Patients After ST-Segment-Elevation Myocardial Infarction: A Magnetic Resonance Imaging Study

Figures & data

Table 1 Baseline Characteristic Comparisons According to General Obesity

Variables	All Patients (n=225)	BMI ≥28 kg/m^2 (n=45)	24.0 ≤BMI <28.0 kg/m^2 (n=113)	18.5 ≤BMI <24.0 kg/m^2 (n=67)	P-value
Age, years	58.41 ± 11.53	55.76 ± 13.28	57.65 ± 11.50	61.48 ± 9.66	0.021
Male	187 (83.1)	41 (91.1)	92 (81.4)	54 (80.6)	0.180
SBP, mmHg	125.13 ± 19.97	125.73 ± 25.69	126.80 ± 19.09	121.91 ± 16.72	0.278
DBP, mmHg	77.14 ± 13.38	78.82 ± 17.14	77.75 ± 12.69	74.97 ± 11.48	0.259
HR, bpm	74.76 ± 14.66	75.11 ± 15.69	74.50 ± 14.58	74.97 ± 14.28	0.963
BMI, kg/m^2	25.83 ± 3.40	31.01 ± 2.23	25.93 ± 1.14	22.16 ± 1.29	<0.001
Waist circumference, cm	92.92 ± 9.78	104.36 ± 7.59	91.86 ± 8.18	86.97 ± 6.68	<0.001
Cardiovascular risk factors
Current or previous smoking, n (%)	159 (70.7)	36 (80.0)	74 (65.5)	49 (73.1)	0.596
Hypertension, n (%)	128 (56.9)	32 (71.1)	66 (58.4)	30 (44.8)	0.005
Diabetes mellitus, n (%)	58 (25.8)	10 (22.2)	32 (28.3)	16 (23.9)	0.943
Dyslipidemia, n (%)	91 (40.4)	19 (42.2)	44 (38.9)	28 (41.8)	0.984
Family history of CAD, n (%)	81 (36.0)	15 (33.3)	39 (34.5)	27 (40.3)	0.420
Medication before admission
Antiplatelet agents, n (%)	25 (11.1)	6 (13.3)	14 (12.4)	5 (7.5)	0.298
ACE-I/ARB, n (%)	47 (20.9)	11 (24.4)	29 (25.7)	7 (10.4)	0.044
Beta-blockers, n (%)	16 (7.1)	4 (8.9)	9 (8.0)	3 (4.5)	0.343
Ca-blockers, n (%)	60 (26.7)	13 (28.9)	30 (26.5)	17 (25.4)	0.689
Statins, n (%)	10 (4.4)	2 (4.4)	3 (2.7)	5 (7.5)	0.351
Killip class, n (%)					0.975
I	183 (81.3)	39 (86.7)	89 (78.8)	55 (82.1)
II	35 (15.6)	5 (11.1)	19 (16.8)	11 (16.4)
III	3 (1.3)	0 (0)	2 (1.8)	1 (1.5)
IV	4 (1.8)	1 (2.2)	3 (2.7)	0 (0)
Site of myocardial infarction
Anterior myocardial infarction	106 (47.1)	22 (48.9)	51 (45.1)	33 (49.3)	0.904
Myocardial enzyme
Peak CK-MB, ng/mL	207.92 (186.55–229.29)	184.33 (136.87–231.79)	194.65 (165.13–224.17)	246.14 (186.55–229.29)	0.067
Total cholesterol, mmol/L	4.96 ± 1.09	4.92 ± 1.00	4.92 ± 1.14	5.04 ± 1.10	0.780
Triglyceride, mmol/L	1.97 ± 1.40	2.21 ± 1.02	2.10 ± 1.73	1.59 ± 0.82	0.027
HDL-C, mmol/L	1.00 ± 0.21	0.95 ± 0.18	0.98 ± 0.21	1.04 ± 0.21	0.053
LDL-C, mmol/L	3.00 ± 0.72	2.97 ± 0.67	2.97 ± 0.75	3.05 ± 0.70	0.773
HbA1c, %	6.60 ± 1.70	6.49 ± 1.34	6.67 ± 1.73	6.55 ± 1.87	0.811
Creatinine, umol/L	71.53 ± 15.84	72.20 ± 14.67	71.67 ± 16.28	70.83 ± 16.06	0.896
eGFR, mL/min/1.73^2	99.99 ± 19.61	104.39 ± 21.67	99.73 ± 19.36	97.47 ± 18.41	0.184
Hs-CRP, mg/L	10.79 ± 10.86	11.33 ± 11.26	11.12 ± 10.87	9.87 ± 10.73	0.708
GRACE risk score	143.45 ± 26.55	137.89 ± 29.47	143.16 ± 27.81	147.67 ± 21.48	0.159
LVEF (Simpson’s), %	51.84 ± 7.97	51.32 ± 7.55	51.82 ± 8.35	52.25 ± 7.68	0.834

Abbreviations: BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; ACEI/ARB, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker; CAD, coronary heart disease; HR, heart rate; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; HbA1c, glycated hemoglobin; eGFR, estimated glomerular filtration rate; CK-MB, creatine kinase MB; Hs-CRP, hypersensitive C-reactive protein; LVEF, left ventricular ejection fraction; GRACE, Global Registry of Acute Coronary Event.

Table 2 CMR Baseline Characteristics

Variables	All Patients (n=225)	BMI ≥28 kg/m^2 (n=45)	24.0 ≤BMI <28.0 kg/m^2 (n=113)	18.5 ≤BMI <24.0 kg/m^2 (n=67)	P-value
LVEDV, mL	139.85 ± 32.94	148.59 ± 36.84	141.85 ± 32.76	130.58 ± 28.46	0.011
LVESV, mL	71.59 ± 28.22	75.91 ± 29.21	72.75 ± 30.10	66.73 ± 23.60	0.199
LVEF, %	42.39 ± 20.21	44.23 ± 18.67	40.55 ± 22.08	44.26 ± 17.72	0.392
LV mass, g	113.28 ± 25.22	128.01 ± 25.17	112.17 ± 23.31	105.24 ± 24.47	<0.001
AAR, g	37.89 ± 23.64	31.98 ± 23.70	38.77 ± 24.32	40.37 ± 22.08	0.157
AAR, % LV mass	32.40 ± 20.40	23.93 ± 18.47	33.11 ± 20.60	36.87 ± 19.86	0.004
LGE mass, g	35.85 ± 26.12	35.69 ± 28.18	36.02 ± 25.74	35.66 ± 25.72	0.995
LGE, % LV mass	30.23 ± 21.15	27.03 ± 21.52	30.69 ± 20.83	31.62 ± 21.54	0.505
MVO mass, g	2.24 ± 4.51	2.60 ± 6.21	2.01 ± 4.01	2.38 ± 3.99	0.727
MVO mass, % LV mass	1.75 ± 3.68	1.86 ± 4.37	1.51 ± 3.00	2.08 ± 3.68	0.560
MVO mass, % LGE mass	4.06 ± 7.02	3.88 ± 8.31	3.71 ± 6.51	4.78 ± 6.96	0.601

Abbreviations: BMI, body mass index; AAR, area at risk; CMR, cardiac magnetic resonance; LGE, late gadolinium enhancement; LVEDV, left ventricular end-diastolic volume; LVEF, left ventricular ejection fraction; LVESV, left ventricular end-systolic volume; LV, left ventricular; MVO, microvascular obstruction.

Figure 1 Percentage MVO and infarct size according to body mass index category.

Abbreviations: BMI, body mass index; MVO, microvascular obstruction.

Table 3 Univariable and Multivariable Predictors of Presence of MVO

Variables	Univariable Analysis		Multivariable Analysis
	OR (95% CI)	P-value	OR (95% CI)	P-value
Age, years	0.99 (0.97–1.02)	0.649	0.99 (0.96–1.01)	0.250
Male	0.89 (0.44–1.80)	0.891	1.09 (0.50–2.38)	0.822
SBP, mmHg	1.00 (0.99–1.02)	0.665
DBP, mmHg	1.01 (0.99–1.03)	0.345
HR, bpm	1.02 (1.00–1.03)	0.094	1.01 (0.99–1.03)	0.296
Waist circumference, cm	0.98 (0.95–1.01)	0.125
18.5≤BMI<24.0 kg/m^2	1.00		1.00
24.0≤BMI<28.0 kg/m^2	0.53 (0.29–0.99)	0.048	0.44 (0.23–0.86)	0.017
BMI ≥28 kg/m^2	0.35 (0.16–0.76)	0.008	0.29 (0.13–0.68)	0.004
Cardiovascular risk factors
Current or previous smoking	0.91 (0.51–1.62)	0.748
Hypertension	1.02 (0.60–1.73)	0.935
Diabetes mellitus	1.83 (0.99–3.38)	0.055
Dyslipidemia	0.55 (0.32–0.94)	0.028
Family history of CAD	0.80 (0.47–1.39)	0.430
Killip class	2.30 (1.25–4.24)	0.008	2.48 (1.32–4.65)	0.005
Site of myocardial infarction
Anterior myocardial infarction	1.15 (0.68–1.94)	0.604
Myocardial enzymes
Peak CK-MB, ng/mL	1.005 (1.003–1.007)	<0.001	1.005 (1.003–1.007)	<0.001
Total cholesterol, mmol/L	0.89 (0.70–1.13)	0.327
Triglyceride, mmol/L	0.87 (0.70–1.07)	0.867
HDL-C, mmol/L	1.07 (0.30–3.81)	0.913
LDL-C, mmol/L	0.90 (0.63–1.30)	0.584
HbA1c, %	1.24 (1.05–1.47)	0.013	1.25 (1.04–1.51)	0.019
GRACE risk score	1.005 (0.995–1.016)	0.285

Abbreviations: MVO, microvascular obstruction; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; ACEI/ARB, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker; CAD, coronary heart disease; HR, heart rate; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; HbA1c, glycated hemoglobin; eGFR, estimated glomerular filtration rate; CK-MB, creatine kinase MB; GRACE, Global Registry of Acute Coronary Event; OR, odd ratio.

Table 4 Multivariable Adjusted Difference in LV Parameters and AAR per Unit Increase in Body Mass Index

Variables	Unadjusted Difference		Adjusted Difference
	(95% Confidence Interval)	P-value	(95% Confidence Interval)	P-value
LVEDV, mL	0.212 (0.807–3.309)	0.001	0.163 (0.303–2.861)	0.016
LV mass, g	0.333 (1.546–3.394)	<0.001	0.234 (0.869–2.602)	<0.001
AAR, g	−0.073 (−1.426–0.406)	0.274	−0.094 (−1.562–0.252)	0.156
AAR, % LV mass	−0.175 (−0.018- −0.003)	0.008	−0.151 (−0.017- −0.001)	0.023

Notes: The multivariable models were adjusted for the following covariate set: age, sex, hypertension, hyperlipidemia, diabetes, current smoking and anterior myocardial infarction.

Abbreviations: AAR, area at risk; LVEDV, left ventricular end-diastolic volume; LV, left ventricular.

Table 5 Multivariable Adjusted Difference in LV Parameters and AAR According to Body Mass Index Category

Variables	Overweight vs Normal Weight		Obese vs Normal Weight
	Adjusted Difference (95% Confidence Interval)	P-value	Adjusted Difference (95% Confidence Interval)	P-value
LVEDV, mL	0.155 (0.593–19.676)	0.038	0.180 (−0.724–24.960)	0.064
LV mass, g	0.081 (−2.638–10.623)	0.236	0.279 (6.228–24.415)	0.001
AAR, g	−0.042 (−9.181–5.124)	0.576	−0.252 (−20.298- −3.244)	0.007
AAR, % LV mass	−0.074 (−0.094–0.032)	0.331	−0.331 (−0.211- −0.062)	<0.001

Notes: The multivariable models were adjusted for the following covariate set: age, sex, hypertension, hyperlipidemia, diabetes, current smoking and anterior myocardial infarction.

Abbreviations: AAR, area at risk; LVEDV, left ventricular end-diastolic volume; LV, left ventricular.

Figure 2 CMR of 2 patients with 18.5 ≤BMI <24.0 kg/m² and BMI ≥28 kg/m² after anterior STEMI and successful PPCI. The top row (A–C) showed a patient with BMI = 23.66 kg/m², the bottom row (D–F) showed a patient with BMI = 29.07 kg/m². (A and D) T2-weighted imaging was used to detect AAR. (B, C, E and F) T1-weighted imaging in LV short and long axis was used to detect LGE and MVO. Despite similar clinical characteristics for 2 groups, patient in 18.5 ≤BMI <24.0 kg/m² group showed both LEG and MVO that were not present in BMI ≥28 kg/m² group.

Abbreviations: BMI, body mass index; AAR, area at risk; CMR, cardiac magnetic resonance; LGE, late gadolinium enhancement; MVO, microvascular obstruction; pPCI, primary percutaneous coronary intervention; STEMI, ST-segment elevation myocardial infarction.