Prognostic Value of Cardiac Magnetic Resonance Feature Tracking Strain in Aortic Stenosis

BACKGROUND

Recent data have suggested that global longitudinal strain (GLS) could be useful for risk stratification of patients with severe aortic stenosis (AS). In this study, we aimed to investigate the prognostic role of GLS in patients with AS and also its incremental value in relation to left ventricular ejection fraction (LVEF) and late gadolinium enhancement (LGE).

METHODS

We analysed all consecutive patients with AS and LGE-CMR in our institution. Survival data were obtained from office of national statistics, a national body where all deaths in England are registered by law. Death certificates were obtained from the general register office.

RESULTS

Some 194 consecutive patients with aortic stenosis were investigated with CMR at baseline and followed up for 7.3 ± 4 years. On multivariate Cox regression analysis, only increasing age remained significant for both all-cause and cardiac mortality, while LGE (any pattern) retained significance for all-cause mortality and had a trend to significance for cardiac mortality. Kaplan-Meier survival analysis demonstrated that patients in the best and middle GLS tertiles had significantly better mortality compared to patients in the worst GLS tertiles. Importantly though, sequential Cox proportional-hazard analysis demonstrated that GLS did not have significant incremental prognostic value for all-cause mortality or cardiac mortality in addition to LVEF and LGE.

CONCLUSIONS

Our study has demonstrated that age and LGE but not GLS are significant poor prognostic indicators in patients with moderate and severe AS.

Circulating intermediate monocytes CD14++CD16+ are increased after elective percutaneous coronary intervention

AIM

Inflammation plays a central role in the pathogenesis of atherosclerosis and in the sequelae of percutaneous coronary intervention (PCI). Previous work demonstrated that intermediate monocytes (CD14++CD16+) are associated with adverse cardiovascular events, yet monocyte subset response following elective PCI has not been described. This article explores the changes in monocyte subset and humoral response after elective PCI.

METHODS

This prospective study included 30 patients without inflammatory diseases being referred for elective PCI. We included patients treated with drug coated balloons or 2nd generation drug eluting stents. Patients underwent blood tests at baseline (prior to PCI), four hours, two weeks and two months later. Analyses were performed in terms of monocyte subsets (classical CD14++CD16-, intermediate CD14++CD16+ and non-classical CD14+CD16++), gene expression of CD14+ leucocytes and humoral biomarkers.

RESULTS

Intermediate monocytes decreased significantly four hours after PCI, were recovered at two weeks, and increased significantly at two months post elective, uncomplicated PCI. They remain significantly elevated in the DES group but not in the DCB group. Gene expression analysis of CD14+ leucocytes showed IL18 had decreased expression at two weeks, CXCR4 and IL1β decreased at two months, while pentraxin 3 increased at two weeks and two months. In terms of humoral biomarkers, hsTnI remains elevated up to two weeks post PCI while IL6 and TNFα remain elevated till two months post PCI.

CONCLUSION

Intermediate monocytes increase significantly two months following elective, uncomplicated PCI. They remain significantly elevated in the DES group but not in the DCB group suggesting that the PCI strategy could be one of the ways to modulate the inflammatory response post PCI.

The role of inflammation in percutaneous coronary intervention, from balloon angioplasty to drug eluting stents

The role of inflammation in percutaneous coronary intervention (PCI) has been investigated in numerous studies. Both pre-PCI and post-PCI inflammatory status have been demonstrated to be linked with patient outcomes. C-reactive protein continues to be the most studied inflammatory biomarker, while a growing number of additional biomarkers, including cytokines and immune cells, are being assessed. As insights are gained into the complexities of the inflammatory response to PCI, it becomes evident that a targeted approach is necessary to ensure optimal patient outcomes. Here, we review the biomarkers that can predict patient outcomes following PCI and specifically how they differ for balloon angioplasty, bare metal stents and drug eluting stents. A specific focus is given to human studies and periprocedural inflammation rather than inflammation associated with myocardial infarction.

Cost effectiveness analysis of drug coated balloon only angioplasty for de novo coronary artery disease

AIMS

We aimed to perform a cost analysis of drug coated balloon (DCB)-only angioplasty versus drug eluting stent (DES), for de novo disease of all vessel sizes and all clinical indications.

BACKGROUND

DCB angioplasty is an emergent technology for the treatment of coronary artery disease. There is lack of data regarding the cost-effectiveness of DCB-only angioplasty for treatment of de novo coronary artery disease as compared with second generation DES.

METHODS

We compared total costs of patients treated with DCB or DES for first presentation of ST-elevation myocardial infarction, non-ST-elevation myocardial infarction, or stable angina due to de novo disease between January 1, 2018 and November 15, 2019. We defined total cost as the sum of (1) procedural devices-cost, (2) procedural staff-cost, (3) post-percutaneous coronary intervention hospital stay cost, and (4) antiplatelet regime cost. A cost minimization analysis was performed to compare the costs of DCB and DES.

RESULTS

We present 1952 all-comer, consecutive patients; 902 (1064 lesions) treated with DCB and 1050 (1236 lesions) treated with DES for de novo coronary artery disease. The cost per patient was estimated to be £9.02 more expensive in the DCB group (£3153.00 vs. £3143.98). However, the cost per lesion treated was calculated to be £15.51 cheaper in the DCB group (£3007.56 vs. £3023.07). The results were consistent irrespective of duration of long-term antiplatelet medications.

CONCLUSION

We have compared the cost-effectiveness of DCB-only angioplasty to DES-angioplasty and showed that the per patient and per lesion results were not different and hence cost should not be implicated in the decision to choose DCB or DES.

Paclitaxel drug-coated balloon-only angioplasty for de novo coronary artery disease in elective clinical practice

OBJECTIVE

We aimed to investigate the safety of drug-coated balloon (DCB)-only angioplasty compared to drug-eluting stent (DES), as part of routine clinical practice.

BACKGROUND

The recent BASKETSMALL2 trial demonstrated the safety and efficacy of DCB angioplasty for de novo small vessel disease. Registry data have also demonstrated that DCB angioplasty is safe; however, most of these studies are limited due to long recruitment time and a small number of patients with DCB compared to DES. Therefore, it is unclear if DCB-only strategy is safe to incorporate in routine elective clinical practice.

METHODS

We compared all-cause mortality and major cardiovascular endpoints (MACE), including unplanned target lesion revascularisation (TLR) of all patients treated with DCB or DES for first presentation of stable angina due to de novo coronary artery disease between 1st January 2015 and 15th November 2019. Data were analysed with Cox regression models and cumulative hazard plots.

RESULTS

We present 1237 patients; 544 treated with DCB and 693 treated with DES for de novo, mainly large-vessel coronary artery disease. On multivariable Cox regression analysis, only age and frailty remained significant adverse predictors of all-cause mortality. Univariable, cumulative hazard plots showed no difference between DCB and DES for either all-cause mortality or any of the major cardiovascular endpoints, including unplanned TLR. The results remained unchanged following propensity score-matched analysis.

CONCLUSION

DCB-only angioplasty, for stable angina and predominantly large vessels, is safe compared to DES as part of routine clinical practice, in terms of all-cause mortality and MACE, including unplanned TLR.

Assessment of Paclitaxel Drug-Coated Balloon Only Angioplasty in STEMI

BACKGROUND

Primary percutaneous coronary intervention (pPCI) with drug-eluting stents (DES) has emerged as the standard of care, but stent-related events have persisted. Drug-coated balloon (DCB)-only angioplasty is an emerging technology, although it is not fully evaluated compared with DES in the context of pPCI.

OBJECTIVES

The aim of this study was to investigate the safety of DCB-only angioplasty compared with second-generation DES in pPCI.

METHODS

All-cause mortality and net adverse cardiac events (cardiovascular mortality, acute coronary syndrome, ischemic stroke or transient ischemic attack, major bleeding, and unplanned target lesion revascularization [TLR]) were compared among all patients treated with DCBs only or with second-generation DES only for first presentation of ST-segment elevation myocardial infarction (STEMI) due to de novo disease between January 1, 2016, and November 15, 2019. Patients treated with both DCBs and DES were excluded. Data were analyzed using Cox regression models, Kaplan-Meier estimator plots and propensity score matching.

RESULTS

Among 1,139 patients with STEMI due to de novo disease, 452 were treated with DCBs and 687 with DES. After a median follow-up period of >3 years, all-cause mortality was 49 of 452 and 62 of 687 in the DCB and DES groups, respectively (P = 0.18). On multivariable Cox regression analysis, there was no difference in mortality between DCBs and DES in the full and propensity score-matched cohorts. Age, frailty risk, history of heart failure, and family history of ischemic heart disease remained significant independent predictors of mortality. There was no difference in any of the secondary endpoints, including unplanned TLR.

CONCLUSIONS

DCB-only angioplasty appears safe compared with DES for STEMI in terms of all-cause mortality and all net adverse cardiac events, including unplanned TLR. DCB may be an efficacious and safe alternative to DES in selected patient groups. (Drug Coated Balloon Only vs Drug Eluting Stent Angioplasty; NCT04482972).

Drug-Coated Balloon vs. Drug-Eluting Stents for De Novo Unprotected Left Main Stem Disease: The SPARTAN-LMS Study

The objective of this study is to compare the outcomes of patients treated with drug-coated balloons (DCBs) or second-generation drug-eluting stents (DESs) for de novo unprotected left main stem (LMS) disease. Previous studies comparing the treatment of LMS disease suggest that the mortality for DES PCI is not worse than CABG. There are limited data from studies investigating the treatment of de novo LMS disease with DCB angioplasty. We compared the all-cause and cardiac mortality of patients treated with paclitaxel DCB to those with second-generation DES for de novo LMS disease from July 2014 to November 2019. Data were analysed using Kaplan-Meier analyses and propensity-matched analyses. A total of 148 patients were treated with either a DCB or DES strategy. There was no significant difference in all-cause mortality in the DCB group (19.5%) compared to the DES group (15.9%) (HR 1.42 [0.61-3.32], p = 0.42). Regarding cardiac mortality, 2 (4.9%) were recorded for the DCB group and 7 (6.5%) for the DES group (HR 1.21 [0.31-4.67], p = 0.786); for target vessel myocardial infarction, there were 0 (0%) for the DCB group and 7 (6.5%) for the DES group; and for target lesion revascularisation, there were 3 (7.3%) in the DCB group and 9 (8.3%) in the DES group (HR: 0.89 [0.24-3.30]). p = 0.86. These remained not significant after propensity score matching. We found no difference in the mortality outcomes with DCB angioplasty compared to second-generation DES, with a median follow-up of 33 months. DCB can therefore be regarded as a safe option in the treatment of LMS disease in suitable patients.

Outcomes of drug coated balloon only angioplasty for stable angina in routine clinical practice

Introduction

The recent BASKETSMALL2 trial demonstrated safety and efficacy of drug coated balloon (DCB) angioplasty for de novo small vessel disease. Registry data have demonstrated that DCB angioplasty is safe; however, the majority of these studies are limited due to long recruitment time and small number of patients with DCB compared to drug eluting stents (DES).

Our aim was to investigate if DCB-only strategy is safe to incorporate in routine clinical practice.

Methods

We identified all patients treated for stable angina and de novo disease in our institution from January 2015 till November 2019. During that period an equivalent number of patients were treated with DCB-only or DES-only strategy on a yearly basis.

The primary endpoint was all cause mortality. The secondary endpoints were cardiovascular mortality, acute coronary syndrome (ACS), ischaemic stroke, major bleeding and target lesion revascularisation (TLR). Data were obtained from the hospital episodes statistics from NHS digital. Clinical and angiographic data were collected from our prospectively collated database and supplemented from electronic records as required. All angiograms were reviewed to confirm accuracy of angiographic data and determine TLR.

On multivariable COX regression analysis (Table 1) age, frailty and hypercholesterolaemia were the only independent predictors of all cause mortality.

Results

A total of 1302 patients were identified. HES data were not obtained for 65 patients who had opted-out, therefore 1237 were included in the analysis; 544 were treated with DCB and 693 with DES. The average age for the DCB-group was 67.9±10.2 years old (79% male); while for the DES group it was 67.9±9.7 years old (78.1% male). The average follow up was 1339±514 days and 1354±527 days for the DCB and DES group respectively. Table 1 shows the differences between the groups in terms of clinical and angiographic characteristics. The DES group had more patients with history of COPD (6.3% vs 3%; p=0.01) and larger average vessel diameter (3.46±0.58 vs 3.09±0.53mm; p<0.001). The DCB group had more patients with true bifurcation disease and TIMI 0 or 1 pre-PCI (11.6% vs 8.1%; p=0.04) and TIMI 0 or 1 pre-PCI (11.7% vs 6.6%; p=0.001). Furthermore, more than 70% of patients in the DCB group had vessel diameter ≥3mm indicating that large vessels were treated.

The all cause mortality was 35 (6.4%) and 59 (8.5%) for the DCB and DES group respectively. Kaplan Meier estimator plot did not show a significant difference between the groups. There was no difference between the groups in any of the secondary endpoints (cardiovascular mortality, ACS, stroke, major bleeding and TLR).

Conclusion

Our real world data from a large, contemporary cohort of stable angina patients, including predominantly large vessels, demonstrate that DCB only angioplasty is safe compared to DES in terms of all major cardiovascular endpoints including TLR.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): B Braun - investigator initiated research

Drug coated balloons for coronary artery bifurcation lesions: A systematic review and focused meta-analysis

Objectives

We sought to systematically review the evidence supporting the role of drug coated balloons (DCBs) in the treatment of coronary bifurcation lesions.

Background

DCBs are emerging as an attractive alternative treatment strategy for treating coronary bifurcations due to simplifying the approach and reducing rates of stent related complications. We systematically reviewed the evidence for DCB use in coronary bifurcations and conducted a focused meta-analysis on late lumen loss in the side branch comparing DCB and plain old balloon angioplasty (POBA).

Methods

This study was conducted in line with the PRISMA statement. All studies (including both RCTs and observational studies, excluding case reports) using DCB as part of a bifurcation strategy were included in this review. A literature search identified a total of ten studies for inclusion. A focused meta-analysis was undertaken for the use of DCB in side-branch compared with POBA. Mean late lumen loss was used with a random effects model due to heterogeneity.

Results

DCB was found to be superior to POBA for side branch treatment in bifurcations (p = 0.01). There are four studies that investigated the use of DCB for main branch treatment in a bifurcation, with evidence supporting its safety in main branches of bifurcation lesions, while prospective observational studies have demonstrated favourable target lesion revascularisation rates.

Conclusion

Although there is a lack of robust RCTs comparing DCBs with current generation DES, DCBs appear safe in main branch bifurcation lesions with improved side branch late lumen loss when compared with DES or POBA.

Diagnostic Applications of Ultrasmall Superparamagnetic Particles of Iron Oxide for Imaging Myocardial and Vascular Inflammation

Cardiac magnetic resonance (CMR) is at the forefront of noninvasive methods for the assessment of myocardial anatomy, function, and most importantly tissue characterization. The role of CMR is becoming even more significant with an increasing recognition that inflammation plays a major role for various myocardial diseases such as myocardial infarction, myocarditis, and takotsubo cardiomyopathy. Ultrasmall superparamagnetic particles of iron oxide (USPIO) are nanoparticles that are taken up by monocytes and macrophages accumulating at sites of inflammation. In this context, USPIO-enhanced CMR can provide valuable additional information regarding the cellular inflammatory component of myocardial and vascular diseases. Here, we will review the recent diagnostic applications of USPIO in terms of imaging myocardial and vascular inflammation, and highlight some of their future potential.

Endothelial Dysfunction and Coronary Vasoreactivity - A Review of the History, Physiology, Diagnostic Techniques, and Clinical Relevance

The fervency for advancement and evolution in percutaneous coronary intervention has revolutionised the treatment of coronary artery disease. Historically, the focus of the interventional cardiologist was directed at the restoration of luminal patency of the major epicardial coronary arteries, yet whilst this approach is evolving with much greater utilisation of physiological assessment, it often neglects consideration of the role of the coronary microcirculation, which has been shown to clearly influence prognosis. In this review, we explore the narrative of the coronary circulation as more than just a simple conduit for blood but an organ with functional significance. We review organisation and physiology of the coronary circulation, as well as the current methods and techniques used to examine it. We discuss the studies exploring coronary artery endothelial function, appreciating that coronary artery disease occurs on a spectrum of disorder and that percutaneous coronary intervention has a latent effect on the coronary circulation with long-term consequences. It is concluded that greater recognition of the coronary artery endothelium and mechanisms of the coronary circulation should further guide revascularisation strategies.

Cardiovascular magnetic resonance: Stressing the future

Non-invasive cardiac stress imaging plays a central role in the assessment of patients with known or suspected coronary artery disease. The current guidelines suggest estimation of the myocardial ischaemic burden as a criterion for revascularisation on prognostic grounds despite the lack of standardised reporting of the magnitude of ischaemia on various non-invasive imaging methods. Future studies should aim to accurately describe the relationship between myocardial ischaemic burden as assessed by cardiovascular magnetic resonance imaging and mortality.

Day case discharge of patients treated with drug coated balloon only angioplasty for de novo coronary artery disease: A single center experience

OBJECTIVE

To report our initial experience with drug coated balloon (DCB) only angioplasty and propose a protocol to achieve this safely.

BACKGROUND

There are no articles published in the literature currently regarding the safety of same day discharge in patients treated with DCB-only angioplasty.

METHODS

Retrospective review of all our patients treated with DCB-only angioplasty from September 2017 to April 2018 with identification of potential complications relating to same day discharge.

RESULTS

A total of 100 consecutive patients who underwent elective DCB-only angioplasty for de novo coronary artery disease and were discharged on the same day as the procedure were included. In 99% no cardiac symptoms relating to the procedure requiring urgent hospitalization or urgent investigations were identified. One patient was readmitted the next day requiring stenting of the previously treated lesion. Our 30-day mortality was zero. Some 97 hospital bed days were saved with 100 patients treated.

CONCLUSION

Elective day-case DCB-only angioplasty according to our local protocol is safe and cost-effective and should be considered for the majority of the patients.

Risk of sudden cardiac death: Are coronary chronic total occlusions an additional risk factor?

Sudden arrhythmic cardiac death remains a significant, potentially reversible, cardiological challenge in terms of creating accurate risk prediction models. The current guidelines for implantable cardioverter defibrillator (ICD) therapy are mainly based on left ventricular ejection fraction despite its low sensitivity and specificity in predicting sudden cardiac death (SCD). Chronic total occlusions have been associated with increased mortality but further research is required to clarify if they should be incorporated in a risk model predicting SCD aiming to identify patients that would benefit from ICD therapy even with preserved ejection fraction.

Percutaneous Coronary Intervention in the Elderly: Are Drug-coated Balloons the Future?

Background:

Balloon angioplasty revolutionised percutaneous treatment for coronary ar-tery disease four decades ago, but vessel-threatening dissections, elastic recoil and restenosis were major drawbacks to an otherwise successful long-lasting intervention. Subsequent advances with bare metal stents and then drug eluting stents followed, aiming to mitigate the risks of acute vessel closure and restenosis. However, stent implantation often necessitates dual antiplatelet therapy for a pro-longed period of time, which in itself can lead to adverse outcomes, especially in the frail elderly pop-ulation at higher risk of bleeding. More recently, bioabsorbable stents have been implemented in clini-cal practice enabling earlier intimal coverage of the stent and apposition.

However, another addition to the armamentarium of percutaneous coronary intervention is the use of drug-coated balloons without the need for deploying any coronary stents or scaffolds. Drug-coated balloons are semi-compliant balloons coated with an antiproliferative agent that is rapidly released on contact with the vessel intima exerting an anti-restenotic effect. The absence of a metallic scaffold means that the need for antiplatelet therapy can potentially be negated in the longer term if required. In this article, we will review the history of percutaneous coronary intervention and the available evi-dence for the appropriate use of drug-coated balloons especially in the elderly population.

Conclusion:

We will conclude this review by demonstrating the potential use of drug-coated balloon rather percutaneous stenting through case examples.

A 'sniff' away from death: a case of cocaine-induced coronary artery dissection

The multiple, deleterious cardiovascular effects of cocaine abuse are well known. Recent data have shown that cocaine abuse in the UK remains high with an upward trend over the last few years and a significant associated mortality/morbidity. Cocaine-induced coronary artery dissection (CAD) is one of the rare totally preventable manifestations of cocaine abuse. With this case report, we aim to contribute to the limited number of cocaine-induced CAD described in literature and increase public awareness in an attempt to reverse the upward trend of cocaine abuse.

Device-identified atrial fibrillation at pacing clinics. Should it guide anticoagulation?

In recent years, there has been a significant increase in the number of devices implanted following improvement in their safety profile, extension of indications and reduction in cost. Although the reason remains largely the beneficial effect on heart rhythm stabilisation, implanted devices might also have additional advantages, notably identification of silent arrhythmia. Should clinicians therefore act on device-identified atrial fibrillation (AF) and should such identification be used to guide anticoagulation management? This review evaluates the current evidence on the management of device-identified asymptomatic AF.

NOAC or Warfarin for Atrial Fibrillation: Does Time in Therapeutic Range Matter?

Atrial fibrillation (AF) is the commonest cardiac arrhythmia currently affecting 1-2% of the general population, with stroke being one of its most fearsome complications. Dose-adjusted warfarin is an established treatment for reduction of thromboembolic risk but mandates dietary restrictions and need for routine blood monitoring. Novel oral anticoagulants (Dabigatran - patent: US20110082299A1, manufactured by Boehringer Ingelheim; Rivaroxaban - patent: US20150175590A1, manufactured by Bayer; Apixaban - patent: US20140335178A1, manufactured jointly by Pfizer and Bristol-Myers Squibb; Edoxaban - patent: WO2013026553A1, manufactured by Daiichi Sankyo) have recently been introduced that might provide at least equal reduction in thromboembolic risk to patients; negating the need for dietary restrictions and routine blood tests. The most recent National Institute of Health and Care Excellence, UK guidelines from August 2014 suggest consideration of one of the novel oral anticoagulants if the time in therapeutic range is less than 65%. In this study, the evidence for four novel oral anticoagulants is reviewed and the anticoagulation success with warfarin with atrial fibrillation and mechanical heart valves assessed in a large UK District General Hospital. Fifty-eight patients were identified with mechanical heart valve and 2737 patients with atrial fibrillation. Patients with atrial fibrillation had a significantly better TTR when compared with the patients included in the NOAC trials. Our results were similar with the Auricula registry. However, 25% of patients had TTR<65% and they would need to be considered for NOACs. Our data suggest that the degree of benefit seen in the NOAC trials might not be expected in our cohort of patients with atrial fibrillation. Interestingly, our patients with atrial fibrillation had a much better mean TTR of 76.4% and required less INR tests (12/year) compared to patients with mechanical heart valve who had a mean TTR of 61.4% and required more INR tests (26/year).

But he has no chest pain

Atypical presentations of acute coronary syndromes (ACS) are not uncommon and have been associated with higher mortality probably, because these patients are misdiagnosed and undertreated. They are most frequently encountered in older patients, women and in patients with diabetes, chronic renal failure or dementia. It is also well described in the literature that many chemotherapy agents are associated with myocardial ischaemic events. In addition to that, patients with cancer frequently receive large doses of opiate analgesics for chronic pain, which can obscure the symptoms of myocardial ischaemia. In this case report, we describe a patient who was receiving chemotherapy and large doses of opiate analgesics and presented with atypical symptoms for ACS. Our aim is to raise awareness of this challenging group of patients and the necessity to pay particular attention to symptoms other than chest pain as potential indicators of myocardial ischaemia.

How sweet is the pacemaker?

Pacemaker infections can be difficult to diagnose, especially when they present with non-specific symptoms and signs a long time after insertion of the device. Unidentified or partially treated low-grade chronic sepsis can result in multisystem disease processes with significant mortality and morbidity. Therefore, a high index of suspicion is required to identify the pacemaker as the source of sepsis and treat it effectively. This report describes a case of chronic pacemaker wire infection, which eventually presented with Sweet's syndrome, a rare manifestation of infective endocarditis.

Amodiaquine and artemether-lumefantrine select distinct alleles of the Plasmodium falciparum mdr1 gene in Tanzanian children treated for uncomplicated malaria

The artemisinin-based combination therapies artemether-lumefantrine (AL) and amodiaquine (AQ) plus artesunate have been adopted for treatment of Plasmodium falciparum malaria in many African countries. Molecular markers of parasite resistance suitable for surveillance have not been established for any of the component drugs in either of these combinations. We assessed P. falciparum mdr1 (Pfmdr1) alleles present in 300 Tanzanian children presenting with uncomplicated falciparum malaria, who were enrolled in a clinical trial of antimalarial therapy. Pfmdr1 genotype analysis was also performed with isolates from 182 children who failed AQ monotherapy and 54 children who failed AL treatment. Pfmdr1 alleles 86Y, 184Y, and 1246Y were more common among treatment failures in the AQ group than among pretreatment infections. The converse was found in the AL-treated group. Children presenting with the 86Y/184Y/1246Y Pfmdr1 haplotype and treated with AQ were significantly more likely to retain this haplotype if they were parasite positive during posttreatment follow-up than were children treated with AL (odds ratio, 33.25; 95% confidence interval, 4.17 to 1441; P, <0.001). We conclude that AL and AQ exert opposite within-host selective effects on the Pfmdr1 gene of P. falciparum.