This study examined the impact of body mass index (BMI) on procedural and long-term outcomes following percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). While obesity is an established cardiovascular risk factor, an “obesity paradox” has been observed in various cardiac interventions, but contemporary data in CTO PCI are limited. We analyzed 503 consecutive CTO PCI procedures in 453 patients at our institution between January 2018 and December 2023, stratified by BMI into obese (≥30 kg/m², n = 213, 42.4%), overweight (25-29.9 kg/m², n = 194, 38.6%), and healthy weight (18.5-24.9 kg/m², n = 96, 19.1%). The primary endpoint was a composite of in-stent restenosis requiring revascularization, heart failure hospitalization, myocardial infarction, and stroke at a median follow-up of 704 days. Obese patients were younger (median 64.0 vs 67.0 vs 68.5 years, p < 0.001) and less frequently current smokers (8.5% vs 10.3% vs 19.8%, p = 0.012). Technical and procedural success were lower in obese patients (79.8% vs 75.8% vs 92.7% and 79.3% vs 75.3% vs 92.7%, respectively; p = 0.002), while radiation exposure increased significantly with BMI (median air kerma: 2385 vs 1688 vs 1126 mGy, p < 0.001). At follow-up, the composite endpoint occurred in 16.5% vs 12.3% vs 16.3% (p = 0.492), with similar all-cause mortality (3.9% vs 6.4% vs 7.0%, p = 0.425). On multivariable analysis, male sex was associated with lower risk of adverse outcomes (HR 0.53, 95% CI 0.30 to 0.95), while baseline heart failure was associated with higher risk (HR 1.83, 95% CI 1.04 to 3.25). In conclusion, despite significantly lower technical and procedural success rates and higher radiation exposure, obese patients undergoing CTO PCI had comparable long-term outcomes to healthy weight patients, supporting the obesity paradox. These findings suggest that BMI alone should not preclude CTO PCI but mandate enhanced radiation safety protocols and careful patient counseling regarding procedural success expectations.
Accumulating evidence suggests that overweight and obese patients may have comparable or even superior outcomes following percutaneous coronary intervention (PCI) compared with their healthy weight counterparts- a phenomenon termed the “obesity paradox”. ,, The pathophysiology underlying the obesity paradox remains incompletely understood and likely multifactorial. Proposed mechanisms include earlier presentation with less severe disease, enhanced metabolic reserve during acute illness, protective effects of certain adipokines, and more aggressive medical therapy in obese patients. , However, these potential benefits must be weighed against obesity-related procedural challenges, including increased radiation exposure, vascular access difficulties, and contrast-induced nephropathy risk. ,,
Previous studies examining the obesity paradox in PCI have yielded conflicting results, with most focusing on acute coronary syndromes or routine PCI populations. ,, Data specifically examining chronic total occlusion (CTO) PCI outcomes across BMI categories remain limited, despite the unique considerations these complex procedures entail. ,,, The OPEN CTO registry reported comparable technical success across BMI categories but noted significant increases in radiation exposure with higher BMI. However, comprehensive long-term outcome data examining the full spectrum of clinical endpoints remain scarce.
Methods
Study design and population
This retrospective cohort study included all consecutive patients undergoing CTO PCI at Houston Methodist DeBakey Heart & Vascular Center between January 2018 and December 2023. This period reflects contemporary CTO practice with routine use of the hybrid algorithm and availability of advanced crossing techniques. CTO was defined as 100% coronary occlusion with Thrombolysis in Myocardial Infarction (TIMI) flow grade 0 of at least 3 months duration, estimated by clinical history, prior angiography, or collateral circulation patterns. The study was approved by the Houston Methodist Institutional Review Board with waiver of informed consent.
Patient stratification
Patients were stratified into 3 groups based on World Health Organization BMI classifications: healthy weight (BMI 18.5-24.9 kg/m²), overweight (BMI 25-29.9 kg/m²), and obese (BMI ≥30 kg/m²). Underweight patients (BMI <18.5 kg/m²) were excluded due to insufficient sample size. BMI was calculated from height and weight measured at the index procedure.
Data collection
Baseline clinical data were systematically extracted from electronic medical records, including demographics, cardiovascular risk factors, cardiac history, medications, presenting symptoms, and laboratory values. Angiographic characteristics were collected through structured review of procedural angiograms and reports by experienced operators. J-CTO scores were calculated for all cases to assess lesion complexity.
To ensure accurate CTO diagnosis and technical success assessment, we implemented a rigorous confirmatory algorithm. All angiograms underwent initial assessment by a primary reviewer (G.S.). When discrepancies arose between the procedural report and primary review, the angiogram was independently evaluated by 2 additional adjudicators (Y.M.S. and R.G.B.C.). In cases where consensus remained elusive, a senior interventionalist (A.R.S.) provided final adjudication. This multitiered review process ensured diagnostic accuracy and consistent outcome assessment across the study cohort.
Procedural data including access sites, crossing strategies, device utilization, contrast volumes, radiation doses, and complications were obtained from catheterization laboratory databases and standardized procedure reports. Follow-up data were collected through systematic review of clinic visits, hospitalizations, repeat procedures, and telephone contact when necessary to ensure comprehensive outcome ascertainment.
Procedural technique
All procedures were performed by operators experienced in CTO PCI (>50 CTO procedures annually) using contemporary techniques. The hybrid algorithm was routinely employed, emphasizing early strategy conversion for procedural efficiency. Dual injection was performed when appropriate to visualize collateral circulation. Choice of initial crossing strategy (antegrade wire escalation, antegrade dissection re-entry, or retrograde) was at operator discretion based on anatomical considerations. Intravascular imaging was encouraged for stent optimization.
Clinical endpoints
The primary endpoint was a composite of target lesion revascularization (TLR) for in-stent restenosis, heart failure hospitalization, myocardial infarction, and stroke. TLR was defined as repeat percutaneous or surgical revascularization of the target lesion due to ≥70% diameter stenosis within the stent or within 5-mm borders, accompanied by ischemic symptoms or positive functional testing. ISR was assessed through clinically driven angiography, as routine angiographic follow-up was not performed. Procedural success was defined as technical success (<30% residual stenosis with TIMI 3 flow) without in-hospital major adverse cardiac events. Follow-up was obtained through clinic visits, telephone contact, and medical record review.
Statistical analysis
Continuous variables were expressed as mean ± standard deviation or median with interquartile range based on distribution. Categorical variables were presented as frequencies and percentages. Comparisons across BMI groups used one-way ANOVA for normally distributed continuous variables, Kruskal-Wallis test for non-normally distributed variables, and chi-square or Fisher’s exact test for categorical variables.
Kaplan-Meier curves estimated event-free survival with log-rank testing for group comparisons. Cox proportional hazards regression identified independent predictors of the primary endpoint, with variables selected based on clinical relevance and univariable significance (p < 0.1). The proportional hazards assumption was verified using Schoenfeld residuals. All analyses were performed using Stata/MP 17.0 and Python 3.12.7, with 2-sided p < 0.05 considered significant.
Results
Patient characteristics
Among 503 CTO procedures in 453 patients, BMI distribution reflected the general interventional population: obese ( n = 213, 42.4%), overweight ( n = 194, 38.6%), and healthy weight( n = 96, 19.1%). Obese patients were significantly younger (median 64.0 vs 67.0 vs 68.5 years, p < 0.001) and less frequently female (20.2% vs 16.0% vs 31.3%, p = 0.010). They demonstrated lower rates of current tobacco use (8.5% vs 10.3% vs 19.8%, p = 0.012) but similar prevalence of diabetes (54.5% vs 47.9% vs 42.7%, p = 0.132) and prior myocardial infarction (28.2% vs 29.4% vs 37.5%, p = 0.237) ( Table 1 ).
Table 1
Demographic characteristics of CTO patients and by BMI
| Characteristic | Overall ( N = 503) | Healthy weight ( n = 96, 19.09%) | Overweight ( n = 194, 38.57%) | Obese ( n = 213,42.35%) | p-value | ||||
|---|---|---|---|---|---|---|---|---|---|
| n/mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | ||
| Age | 67.00 | [59.00, 72.70] | 68.50 | [61.50, 76.00] | 67.00 | [61.00, 73.00] | 64.00 | [58.00, 69.80] | <0.001 |
| Female | 104 | 20.68 | 30 | 31.25 | 31 | 15.98 | 43 | 20.19 | 0.010 |
| Race | 0.003 | ||||||||
| White | 387 | 77.25 | 73 | 76.04 | 136 | 70.10 | 178 | 84.36 | |
| Black | 55 | 10.98 | 7 | 7.29 | 28 | 14.43 | 20 | 9.48 | |
| Other | 59 | 11.78 | 16 | 16.67 | 30 | 15.46 | 13 | 6.16 | |
| BMI | 29.00 | [25.90, 32.70] | 23.70 | [22.60, 24.40] | 27.60 | [26.70, 28.90] | 33.30 | [31.60, 35.90] | <0.001 |
| Hypertension | 483 | 96.02 | 91 | 94.79 | 186 | 95.88 | 206 | 96.71 | 0.694 |
| DM | 250 | 49.70 | 41 | 42.71 | 93 | 47.94 | 116 | 54.46 | 0.132 |
| Prior stroke | 64 | 12.72 | 12 | 12.50 | 31 | 15.98 | 21 | 9.86 | 0.180 |
| Dyslipidemia | 474 | 94.23 | 90 | 93.75 | 184 | 94.85 | 200 | 93.90 | 0.896 |
| Current tobacco use | 57 | 11.33 | 19 | 19.79 | 20 | 10.31 | 18 | 8.45 | 0.012 |
| Cerebrovascular disease | 84 | 16.70 | 18 | 18.75 | 43 | 22.16 | 23 | 10.80 | 0.007 |
| Peripheral arterial disease | 97 | 19.28 | 16 | 16.67 | 34 | 17.53 | 47 | 22.07 | 0.393 |
| Chronic lung disease | 39 | 7.75 | 10 | 10.42 | 10 | 5.15 | 19 | 8.92 | 0.203 |
| Afib/flutter | 95 | 18.89 | 18 | 18.75 | 36 | 18.56 | 41 | 19.25 | 0.984 |
| Family history of premature CAD | 34 | 6.76 | 6 | 6.25 | 13 | 6.70 | 15 | 7.04 | 0.967 |
| Prior cardiac arrest | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | – |
| CKD | 175 | 34.79 | 42 | 43.75 | 58 | 29.90 | 75 | 35.21 | 0.065 |
| Current dialysis | 29 | 5.77 | 6 | 6.25 | 11 | 5.67 | 12 | 5.63 | 0.975 |
| Heart failure | 121 | 24.06 | 31 | 32.29 | 44 | 22.68 | 46 | 21.60 | 0.107 |
| Prior MI | 153 | 30.42 | 36 | 37.50 | 57 | 29.38 | 60 | 28.17 | 0.237 |
| Prior PCI | 304 | 60.44 | 55 | 57.29 | 121 | 62.37 | 128 | 60.09 | 0.701 |
| Prior CABG | 124 | 24.65 | 21 | 21.88 | 57 | 29.38 | 46 | 21.60 | 0.149 |
Angiographic and procedural characteristics
J-CTO scores were comparable across groups (median 2.0 for all groups, p = 0.998), indicating similar anatomical complexity. However, specific characteristics differed: obese patients more frequently had previously failed attempts (13.2% vs 8.8% vs 4.2%, p = 0.041). Collateral patterns varied significantly (p = 0.018), with obese patients more often demonstrating combined ipsilateral and contralateral collaterals (12.7% vs 6.7% vs 3.1%).
Procedural metrics revealed important BMI-related differences. While fluoroscopy times were similar (median 37.1 vs 35.9 vs 31.8 minutes, p = 0.268), radiation exposure increased dramatically with BMI. Median cumulative air kerma doubled from obese to healthy weight patients (2385 vs 1688 vs 1126 mGy, p < 0.001), with dose area product showing similar patterns (12,180 vs 8663 vs 5623 Gy·cm², p < 0.001). Contrast volume was similar across groups (median 204 vs 208 vs 200 mL, p = 0.203). Intravascular ultrasound utilization was similar across groups (32.6% vs 30.7% vs 36.8%, p = 0.578) ( Tables 2-4 ).
Table 2
Procedural, angiographic, and technical characteristics
| Characteristic | Overall ( N = 503) | Healthy weight ( n = 96, 19.09%) | Overweight ( n = 194, 38.57%) | Obese ( n = 213, 42.35%) | p-value | ||||
|---|---|---|---|---|---|---|---|---|---|
| n/mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | ||
| Fluoroscopy time (min) | 35.50 | [24.90, 50.00] | 31.80 | [23.80, 48.85] | 35.90 | [25.60, 48.50] | 37.10 | [25.50, 52.70] | 0.268 |
| Contrast Volume | 200.00 | [160.00, 270.00] | 200.00 | [160.00, 230.00] | 207.50 | [160.00, 270.00] | 204.00 | [160.00, 270.00] | 0.203 |
| Cumulative Air Kermam | 1884.00 | [1181.00, 2760.00] | 1126.00 | [781.00, 1858.00] | 1688.00 | [1147.00, 2376.00] | 2384.50 | [1644.00, 3344.00] | <0.001 |
| Dose area product | 8717.00 | [2954.75, 15616.00] | 5623.00 | [2944.00, 9579.50] | 8662.50 | [3508.00, 14438.00] | 12180.00 | [2618.90, 19882.00] | <0.001 |
| Procedure time (min) | 99.00 | [77.00, 123.00] | 97.50 | [72.00, 118.50] | 96.00 | [77.00, 120.00] | 103.00 | [80.00, 129.00] | 0.251 |
| Procedure time (hr) | 1.67 | [1.28, 2.03] | 1.63 | [1.20, 2.00] | 1.60 | [1.28, 2.00] | 1.71 | [1.33, 2.14] | 0.268 |
| Coronary circulation dominance | 0.174 | ||||||||
| Co-dominant | 12 | 2.40 | 1 | 1.04 | 2 | 1.04 | 9 | 4.25 | |
| Left | 31 | 6.19 | 8 | 8.33 | 13 | 6.74 | 10 | 4.72 | |
| Right | 458 | 91.42 | 87 | 90.63 | 178 | 92.23 | 193 | 91.04 | |
| CTO target vessel | 0.175 | ||||||||
| LAD | 177 | 35.19 | 34 | 35.42 | 69 | 35.57 | 74 | 34.74 | |
| LCX | 80 | 15.90 | 18 | 18.75 | 28 | 14.43 | 34 | 15.96 | |
| RCA | 230 | 45.73 | 39 | 40.63 | 87 | 44.85 | 104 | 48.83 | |
| LM | 10 | 1.99 | 3 | 3.13 | 6 | 3.09 | 1 | 0.47 | |
| SVG | 2 | 0.40 | 0 | 0.00 | 2 | 1.03 | 0 | 0.00 | |
| LIMA | 3 | 0.60 | 1 | 1.04 | 2 | 1.03 | 0 | 0.00 | |
| Number of native Vessels with stenosis | 2.00 | [1.00, 3.00] | 2.00 | [1.00, 3.00] | 1.50 | [1.00, 3.00] | 2 | [1.00, 2.00] | 0.932 |
| Number of native vessels with stenosis | 0.627 | ||||||||
| 1 | 241 | 47.91 | 47 | 48.96 | 97 | 50.00 | 97 | 45.54 | |
| 2 | 135 | 26.84 | 24 | 25.00 | 46 | 23.71 | 65 | 30.52 | |
| ≥3 | 127 | 25.25 | 25 | 26.04 | 51 | 26.29 | 51 | 23.94 | |
| Graft vessel with stenosis | 49 | 9.74 | 11 | 11.46 | 21 | 10.82 | 17 | 7.98 | 0.514 |
| Lesion in graft | 7 | 1.39 | 1 | 1.04 | 5 | 2.58 | 1 | 0.47 | 0.177 |
| Previously treated lesion | 86 | 17.10 | 16 | 16.67 | 31 | 15.98 | 39 | 18.31 | 0.817 |
| In-stent lesion | 82 | 16.47 | 17 | 17.89 | 28 | 14.58 | 37 | 17.54 | 0.667 |
| Number of lesion | 0.944 | ||||||||
| 1 | 280 | 55.67 | 53 | 55.21 | 104 | 53.61 | 123 | 57.75 | |
| 2 | 137 | 27.24 | 26 | 27.08 | 55 | 28.35 | 56 | 26.29 | |
| ≥3 | 86 | 17.10 | 17 | 17.71 | 35 | 18.04 | 34 | 15.96 | |
| Multiple CTOs | 50 | 9.94 | 6 | 6.25 | 23 | 11.86 | 21 | 9.86 | 0.324 |
| Severe 70% stenosis Non-CTO | 0.560 | ||||||||
| 0 | 282 | 56.06 | 53 | 51.12 | 106 | 54.64 | 123 | 57.75 | |
| 1 | 194 | 38.57 | 39 | 55.21 | 73 | 37.63 | 82 | 38.50 | |
| 2 | 20 | 3.98 | 2 | 40.63 | 12 | 6.19 | 6 | 2.82 | |
| ≥3 | 7 | 1.39 | 2 | 2.08 | 3 | 1.55 | 2 | 0.94 | |
| Bifurcation lesion | 38 | 7.55 | 6 | 6.25 | 14 | 7.22 | 18 | 8.45 | 0.775 |
| Arterial access site | 0.825 | ||||||||
| Femoral | 394 | 78.33 | 76 | 79.17 | 156 | 80.41 | 162 | 76.06 | |
| Radial | 107 | 21.27 | 20 | 20.83 | 38 | 19.59 | 49 | 23.00 | |
| Radial and femoral | 1 | 0.20 | 0 | 0.00 | 0 | 0.00 | 1 | 0.47 | |
| Ulnar and femoral | 1 | 0.20 | 0 | 0.00 | 0 | 0.00 | 1 | 0.47 | |
| Arterial CrossOver | 18 | 3.58 | 3 | 3.13 | 5 | 2.58 | 10 | 4.69 | 0.489 |
Table 3
Procedural, angiographic, and technical characteristics (continued)
| Characteristic | Overall ( N = 503) | Healthy weight ( n = 96, 19.09%) | Overweight ( n = 194, 38.57%) | Obese ( n = 213, 42.35%) | p-value | ||||
|---|---|---|---|---|---|---|---|---|---|
| n/mean/median | %/Std/IQR | n/mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | n/ mean/median | %/Std/IQR | ||
| Venous access | 251 | 49.90 | 40 | 41.67 | 103 | 53.09 | 108 | 50.70 | 0.178 |
| Femoral access | 0.715 | ||||||||
| Absent | 32 | 6.36 | 8 | 8.33 | 11 | 5.67 | 13 | 6.10 | |
| Single | 193 | 38.37 | 39 | 40.63 | 68 | 35.05 | 86 | 40.38 | |
| Dual | 182 | 36.18 | 32 | 33.33 | 79 | 40.72 | 71 | 33.33 | |
| Radial and femoral | 96 | 19.09 | 17 | 17.71 | 36 | 18.56 | 43 | 20.19 | |
| Collaterals | 0.018 | ||||||||
| Absent | 198 | 39.36 | 41 | 42.71 | 69 | 35.57 | 88 | 41.31 | |
| Ipsilateral | 86 | 17.10 | 21 | 21.88 | 31 | 15.98 | 34 | 15.96 | |
| Contralateral | 176 | 34.99 | 31 | 32.29 | 81 | 41.75 | 64 | 30.05 | |
| Ipsilateral and contralateral | 43 | 8.55 | 3 | 3.13 | 13 | 6.70 | 27 | 12.68 | |
| Lesion preparation | |||||||||
| Lithotripsy | 3 | 0.60 | 1 | 1.04 | 1 | 0.52 | 1 | 0.47 | 0.603 |
| Atherectomy rota/orbital | 17 | 3.38 | 2 | 2.08 | 9 | 4.64 | 6 | 2.82 | 0.525 |
| Laser atherectomy | 17 | 3.38 | 4 | 4.17 | 7 | 3.61 | 6 | 2.82 | 0.769 |
| Brachytherapy | 20 | 3.98 | 5 | 5.21 | 6 | 3.09 | 9 | 4.23 | 0.662 |
| PCI for multi vessel disease | 253 | 50.30 | 49 | 51.04 | 96 | 49.48 | 108 | 50.70 | 0.958 |
| Lesion length | 32.00 | [20.00, 40.00] | 38.00 | [24.00, 48.00] | 28.00 | [20.00, 38.00] | 32.00 | [20.00, 40.00] | 0.057 |
| <20 | 136 | 27.04 | 19 | 19.79 | 57 | 29.38 | 60 | 28.17 | 0.175 |
| >20 and ≤40 | 244 | 48.51 | 45 | 46.88 | 93 | 47.94 | 106 | 49.77 | |
| >40 | 123 | 24.45 | 32 | 33.33 | 44 | 22.68 | 47 | 22.07 | |
| Mean CTO vessel diameter | 3.00 | [2.50, 3.50] | 3.00 | [2.50, 3.50] | 3.00 | [2.50, 3.50] | 3.00 | [2.50, 3.50] | 0.569 |
| CTO vessel diameter | 0.346 | ||||||||
| 1.5 | 1 | 0.20 | 0 | 0.00 | 0 | 0.00 | 1 | 0.47 | |
| 2 | 26 | 5.17 | 1 | 1.04 | 11 | 5.67 | 14 | 6.57 | |
| 2.25 | 37 | 7.36 | 10 | 10.42 | 15 | 7.73 | 12 | 5.63 | |
| 2.5 | 97 | 19.28 | 15 | 15.63 | 41 | 21.13 | 41 | 19.25 | |
| 2.75 | 16 | 3.18 | 2 | 2.08 | 7 | 3.61 | 7 | 3.29 | |
| 3 | 161 | 32.01 | 37 | 38.54 | 58 | 29.90 | 66 | 30.99 | |
| 3.25 | 8 | 1.59 | 0 | 0.00 | 6 | 3.09 | 2 | 0.94 | |
| 3.5 | 106 | 21.07 | 18 | 18.75 | 35 | 18.04 | 53 | 24.88 | |
| 4 | 47 | 9.34 | 12 | 12.50 | 19 | 9.79 | 16 | 7.51 | |
| 4.5 | 3 | 0.60 | 1 | 1.04 | 1 | 0.52 | 1 | 0.47 | |
| 5 | 1 | 0.20 | 0 | 0.00 | 1 | 0.52 | 0 | 0.00 | |
| First crossing | 0.362 | ||||||||
| Antegrade | 468 | 93.04 | 90 | 93.75 | 186 | 95.88 | 192 | 90.14 | |
| Antegrade dissection reentry | 9 | 1.79 | 2 | 2.08 | 2 | 1.03 | 5 | 2.35 | |
| Retrograde | 25 | 4.97 | 4 | 4.17 | 6 | 3.09 | 15 | 7.04 | |
| Number of wires used | 2.00 | [3.00, 5.00] | 4.00 | [3.00, 5.00] | 2.00 | [3.00, 5.00] | 3.00 | [3.00, 5.00] | 0.202 |
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