Deconstructing the Paradox of Smoking and Improved Short-Term Cardiovascular Outcomes After Myocardial Infarction

The enigma of the 'smoker's paradox': Results from a single-center registry of patients with STEMI undergoing primary percutaneous coronary intervention

BACKGROUND

Smoker's paradox usually refers to the observation of a favorable outcome of smoking patients in acute myocardial infarction.

METHODS

From April 2006 to December 2018 a population of 2456 patients with ST segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI) were prospectively enrolled in the MATRIX registry. Ischemic time, clinical, demographics, angiographic data, and 1-year follow-up were collected.

RESULTS

Among 2546 patients admitted with STEMI, 1007 (41 %) were current smokers. Smokers were 10 years younger and had lower crude in-hospital and 1-year mortality (1.5 % vs 6 %, p < 0.0001 and 5 % vs 11 %, p < 0.0001), shorter ischemic time (203 [147-299] vs 220 [154-334] minutes, p = 0.002) and shorter decision time (60 [30-135] vs 70 [36-170] minutes, p = 0.0063). Smoking habit [OR:0.37(95 % CI:0.18-0.75)-p < 0.01], younger age [OR 1.06 (95%CI:1.04-1.09)-p < 0.001] and shorter ischemic time [OR:1.01(95%CI:1.01-1.02)-p < 0.05] were associated to lower in-hospital mortality. Only smoking habit [HR:0.65(95 % CI: 0.44-0.9)-p = 0.03] and younger age [HR:1.08 (95%CI:1.06-1.09)-p < 0.001] were also independently associated to lower all-cause death at 1-year follow-up. After propensity matching, age, cardiogenic shock and TIMI flow <3 were associated with in-hospital mortality, while smoking habit was still associated with reduced mortality. Smoking was also associated with reduced mortality at 1-year follow-up (HR 0.54, 95 % CI [0.37-0.78]; p < 0.001).

CONCLUSIONS

Smoking patients show better outcome after PCI for STEMI at 1-year follow-up. Although "Smoking paradox" could be explained by younger age of patients, other factors may have a role in the explanation of the phenomenon.

Unfolding the reality of the smoking paradox in a South Asian cohort of patients presenting with ST-elevation acute coronary syndrome undergoing primary percutaneous coronary intervention

Objectives

Smoking is a potent risk factor for coronary artery disease, but there is controversy about its protective nature in terms of prognosis in ST-elevation acute coronary syndrome patients undergoing primary percutaneous coronary intervention. So, the main objective of this study is to unfold this controversy in a South Asian population in terms of clinical angiographic parameters and its in-hospital outcomes.

Methods

In this study, we included 1756 consecutive patients diagnosed with ST-elevation acute coronary syndrome undergoing primary percutaneous coronary intervention. Patients were classified into smokers and non-smokers, and the in-hospital mortality rate was compared. Multivariable logistic regression analysis was performed to evaluate the paradoxical role of smoking.

Results

Smokers were younger (53.78 ± 11.16 years vs 56.43 ± 11.17 years; p < 0.001) and more frequently men (98.7% vs 69.9%; p < 0.001) and had less diabetes (19.6% vs 44.8%; p < 0.001) and hypertension (38.5% vs 64.9%; p < 0.001). Smokers presented less frequently in Killip III (5.6% vs 8.1%; p < 0.001) and Killip IV (2.5% vs 4.8%; p < 0.001). Smokers mostly had single vessel disease (41.7% vs 34.4%; p = 0.013), whereas non-smokers had the multi-vessel disease and frequently presented with total occlusion of the culprit vessel (64.6% vs 58.8%; p = 0.040). Smokers have significantly lesser mortality (1.8% vs 4.3%; p = 0.009) compared to non-smokers with an odds ratio of 0.41 (95% confidence interval (CI): 0.21-0.82, p = 0.011); however, adjusted odds ratio on multivariable analysis was 0.67 (95% CI: 0.31-1.41, p = 0.290).

Conclusions

The paradoxical protective role of smoking is the confounding effect of mainly younger age, less coronary artery disease burden, lower prevalence of diabetes and hypertension, and lower Killip III/IV at presentation.

Meta-Analysis of Gender Disparities in In-hospital Care and Outcomes in Patients with ST-Segment Elevation Myocardial Infarction

Gender disparities in ST-segment elevation myocardial infarction (STEMI) outcomes continue to be reported worldwide; however, the magnitude of this gap remains unknown. To evaluate gender-based discrepancies in clinical outcomes and identify the primary driving factors a global meta-analysis was performed. Studies were selected if they included all comers with STEMI, reported gender specific patient characteristics, treatments, and outcomes, according to the registered PROSPERO protocol: CRD42020161469. A total of 56 studies (705,098 patients, 31% females) were included. Females were older, had more comorbidities and received less antiplatelet therapy and primary percutaneous coronary intervention (PCI). Females experienced significantly longer delays to first medical contact (mean difference 42.5 min) and door-to-balloon time (mean difference 4.9 min). In-hospital, females had increased rates of mortality (odds ratio [OR] 1.91, 95% confidence interval [CI] 1.84 to 1.99, p <0.00001), repeat myocardial infarction (MI) (OR 1.25, 95% CI 1.00 to 1.56, p=0.05), stroke (OR 1.67, 95% CI 1.27 to 2.20, p <0.001), and major bleeding (OR 1.82, 95% CI 1.56 to 2.12, p <0.00001) compared with males. Older age at presentation was the primary driver of excess mortality in females, although other factors including lower rates of primary PCI and aspirin usage, and longer door-to-balloon times contributed. In contrast, excess rates of repeat MI and stroke in females appeared to be driven, at least in part, by lower use of primary PCI and P2Y12 inhibitors, respectively. In conclusion, despite improvements in STEMI care, women continue to have in-hospital rates of mortality, repeat MI, stroke, and major bleeding up to 2-fold higher than men. Gender disparities in in-hospital outcomes can largely be explained by age differences at presentation but comorbidities, delays to care and suboptimal treatment experienced by women may contribute to the gender gap.

Baseline factors identified for the prediction of good responders in patients with end-stage diffuse coronary artery disease undergoing intracoronary CD34+ cell therapy

Background

Treating patients with end-stage diffuse coronary artery disease (EnD-CAD) unsuitable for coronary intervention remains a clinical challenge. They usually express refractory angina and have a high risk of mortality. Although growing data have indicated cell therapy is an alternative solution to medical or invasive therapy, there are still lacking useful markers to predict whether heart function will improve in the EnD-CAD patients who underwent circulatory-derived CD34+ cell therapy. By utilizing the baseline variables and results from our previous phase I/II clinical trials, the aim of this study tried to elucidate the variables predictive of the “good response” to CD34+ cell therapy.

Methods

This retrospective study included 38 patients in phase I clinical trial (2011–2014), and 30 patients in phase II clinical trial (2013–2017). These patients were categorized into “good responders” and “non-responders” according to their 1-year improvement of LVEF ≥ 7.0% or < 7.0% after intracoronary CD34+ cell therapy. Univariate and multivariate logistic regression models were performed to identify potential independent predictors of a good responder to cell therapy, followed by Hosmer–Lemeshow (H-L) test for goodness of fit and prediction power.

Results

Among baseline data, multivariate analysis demonstrated that the history of a former smoker was independently predictive of good responders (p = 0.006). On the other hand, male gender, the baseline Canadian Cardiovascular Society angina score ≥ 3, and grades of LV diastolic dysfunction ≥ 2 were significantly negative predictors of good responders (all p < 0.01). After administration of subcutaneous granulocyte-colony stimulating factor (G-CSF), a higher post-G-CSF neutrophil count in addition to the above four baseline variables also played crucial roles in early prediction of good response to CD34+ cell therapy for EnD-CAD (all p < 0.03). The H-L test displayed a good prediction power with sensitivity 83.3%, specificity 85.3%, and accuracy 84.4%.

Conclusions

Using the results of our phase I/II clinical trials, previous smoking habit, female sex, lower grades of angina score, and diastolic dysfunction were identified to be independently predictive of “good response” to CD34+ cell therapy in the patients with EnD-CAD.

Trial registration

This is a retrospective analysis based on phase I (ISRCTN72853206) and II (ISRCTN26002902) clinical trials.