Andrew C Y To

Cleveland Clinic, Cleveland, Ohio, United States

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Publications (29)176.01 Total impact

  • Heart (British Cardiac Society) 03/2013; DOI:10.1136/heartjnl-2012-301751 · 6.02 Impact Factor
  • Journal of the American College of Cardiology 07/2012; 60(2):165. DOI:10.1016/j.jacc.2011.11.077 · 15.34 Impact Factor
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    Lee Fong Ling, Andrew C.Y. To, Venugopal Menon
    Journal of the American College of Cardiology 04/2012; 59(16):e31. DOI:10.1016/j.jacc.2011.06.086 · 15.34 Impact Factor
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    Andrew C Y To, Harry M Lever, Milind Y Desai
    Journal of the American College of Cardiology 03/2012; 59(13):1197. DOI:10.1016/j.jacc.2011.08.083 · 15.34 Impact Factor
  • Andrew C Y To, Milind Y Desai
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    ABSTRACT: One of the diagnostic challenges in cardiology is the assessment of patients with suspected cardiomyopathies. The traditional approach involves clinical history and examination, followed by echocardiography and invasive angiography. Advances in cardiac MRI enable cardiologists to comprehensively assess both ischemic and nonischemic cardiomyopathies, providing information regarding cardiac anatomy, myocardial and valve functions, as well as tissue characterization.
    Expert Review of Cardiovascular Therapy 02/2012; 10(2):223-33. DOI:10.1586/erc.11.194
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    ABSTRACT: The patho-physiology of apical ballooning syndrome (ABS) has not been clearly defined. The aim of this study was to determine whether patients with a history of ABS are more likely to develop left ventricular (LV) mid-cavity or outflow tract obstruction, or have a greater regional LV contractile response to an adrenergic stimulus compared with normal controls. Twenty patients who had recovered from ABS and 15 age-and sex-matched controls had dobutamine stress echocardiography with incremental doses up to 20 µg/kg/min. On average ABS subjects had slightly greater basal LV interventricular septal (1.1 ± 0.24 cm vs. 0.93 ± 0.12, P = 0.03) and posterior wall (1.04 ± 0.16 vs. 0.91 ± 0.11 cm, P = 0.02) diameters compared with controls but LV end-diastolic and end-systolic volumes and LV ejection fraction were similar both at rest and after dobutamine. Regional and global LV contractility, measured with the strain rate and tissue velocity imaging were also similar during the dobutamine infusion up to 10 µg/kg/min in ABS and controls. Mid-LV or LV outflow tract obstruction was not present at rest in any subjects, but was common during peak dobutamine infusion both in the ABS (45%) and controls (53%, P = 0.62). Dynamic LV obstruction with dobutamine is common in those with and without prior ABS. However, this study did not identify a greater individual predisposition to LV obstruction, or a different regional or global LV contractile response to dobutamine in patients with a history of ABS compared with control subjects.
    12/2011; 13(6):510-6. DOI:10.1093/ejechocard/jer303
  • Circulation 10/2011; 124(17):1897-8. DOI:10.1161/CIRCULATIONAHA.111.030213 · 14.95 Impact Factor
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    Journal of the American College of Cardiology 10/2011; 58(15):1637. DOI:10.1016/j.jacc.2011.03.070 · 15.34 Impact Factor
  • Andrew C Y To, Ashwat Dhillon, Milind Y Desai
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    ABSTRACT: Hypertrophic cardiomyopathy is a complex genetic cardiovascular disorder with substantial variability in phenotypic expression and natural progression. Recent research demonstrates the incremental utility of cardiac magnetic resonance in the diagnosis, therapeutic planning, and prognostication of this disease. The increasing incorporation of multimodality imaging of hypertrophic cardiomyopathy in clinical practice will continue to improve our understanding of the subtle morphologic differences and their prognostic implications.
    JACC. Cardiovascular imaging 10/2011; 4(10):1123-37. DOI:10.1016/j.jcmg.2011.06.022 · 6.99 Impact Factor
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    ABSTRACT: The reservoir, conduit, and contractile functions of the left atrium are integral to overall cardiac performance. Recent advances in cardiac imaging offer the accurate assessment of LA phasic functions and structure, using techniques such as 3-dimensional echocardiography, color tissue Doppler imaging, and speckle tracking, as well as cardiac computed tomography and magnetic resonance imaging. These new developments are particularly important in view of the increasing use of intervention involving the left atrium. This review article highlights and contrasts the imaging of the size, mechanics, and structure of the left atrium using multiple modalities. The authors discuss recent studies on the clinical applications of the various techniques in disease conditions.
    JACC. Cardiovascular imaging 07/2011; 4(7):788-98. DOI:10.1016/j.jcmg.2011.02.018 · 6.99 Impact Factor
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    ABSTRACT: Computed tomography (CT) is the gold standard for assessing pulmonary vein (PV) anatomy and stenosis after ablation for atrial fibrillation (AF), but radiation exposure can be a concern. Transesophageal echocardiography (TEE) provides anatomic and functional assessment of the PVs, although no study has prospectively compared findings on TEE with those on CT. The Role of Transesophageal Echocardiography Compared to Computed Tomography in Evaluation of Pulmonary Vein Ablation for Atrial Fibrillation (ROTEA) study was a prospective, single-blinded observational study of patients with paroxysmal or persistent AF undergoing ablation. TEE and CT were performed immediately before and 3 months after AF ablation. The study included 43 patients (84% men; mean age, 56 ± 11 years). In the preprocedural study, TEE identified 98% of PVs with adequate Doppler measurements obtained. After ablation, no moderate or severe PV stenosis was detected on CT, and a 30% to 50% reduction in luminal diameter was seen in 5% of studied veins. Functional PV stenosis by pulsed-wave Doppler was seen in two veins on TEE. PV diameters decreased after ablation by 0.20 ± 0.03 and 0.22 ± 0.03 cm as measured by CT and TEE, respectively (P < .001). However, TEE underestimated PV ostial dimensions compared with CT, especially for the inferior PVs. Severe spontaneous echo contrast and low left atrial appendage emptying velocities, were identified in 10% of patients in sinus rhythm after ablation. In the ROTEA study, TEE was feasible in assessing PVs before and after ablation, providing both anatomic and functional information that complemented CT. PV ostial dimensions after ablation can be monitored using either modality, although TEE underestimates PV dimensions, especially for the inferior veins.
    Journal of the American Society of Echocardiography: official publication of the American Society of Echocardiography 06/2011; 24(9):1046-55. DOI:10.1016/j.echo.2011.05.014 · 3.99 Impact Factor
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    Journal of the American College of Cardiology 01/2011; 57(3):e5. DOI:10.1016/j.jacc.2010.07.048 · 15.34 Impact Factor
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    Journal of the American College of Cardiology 10/2010; 56(18):1513. DOI:10.1016/j.jacc.2010.04.059 · 15.34 Impact Factor
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    Milind Y Desai, Ashwat Dhillon, Andrew C Y To
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    ABSTRACT: Hypertrophic cardiomyopathy is a fascinating and complex disorder with substantial variability in phenotypic expression and natural progression. Recently, there has been substantial research demonstrating incremental utility of cardiac magnetic resonance in the diagnosis and treatment of this disease. With the increasing utilization of multimodality imaging, our understanding of the subtle morphologic differences and their prognostic implications is only going to improve.
    Current Cardiology Reports 10/2010; 13(1):67-76. DOI:10.1007/s11886-010-0149-y
  • Journal of the American College of Cardiology 03/2010; 55(10). DOI:10.1016/S0735-1097(10)60777-2 · 15.34 Impact Factor
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    ABSTRACT: Apical ballooning syndrome (ABS) is characterised by transient regional systolic dysfunction involving the left ventricular apex and mid-myocardial segments. The absence of obstructive coronary disease is required in some diagnostic criteria. Some investigators have suggested that a long "wrap-around" left anterior descending (LAD) artery may explain the pattern of regional wall motion abnormalities. We reviewed the coronary angiograms and ventriculograms findings in a prospective ABS cohort of 46 patients (mean age 63+/-13, female 96%). Normal smooth coronary arteries were observed in 54%, with 30% having minor irregularities. Moderate or severe coronary artery lesions were identified in 7 (15%) patients, including 4 with moderate LAD disease. The extent of the LAD artery around the left ventricular apex to the diaphragmatic surface of the heart was scored. This score was compared to 60 consecutive gender-matched control patients without ABS and no observed difference between the two groups (p=0.62). 42% had sparing of LV apical akinesis which was independent of the LAD extent. Moderate or severe coronary artery stenosis may co-exist in a small proportion of patients with ABS. Exclusion of these patients will underestimate the true incidence of ABS. The prevalence of "wrap-around" LAD is similar in ABS and non-ABS patients. Apical sparing in ABS is more consistent with aetiological hypotheses implicating LV stunning due to acutely elevated LV wall stress, rather than single or multi-vessel coronary spasm.
    Heart, Lung and Circulation 02/2010; 19(4):219-24. DOI:10.1016/j.hlc.2010.01.003 · 1.17 Impact Factor
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    ABSTRACT: The decision on whether to implant a drug-eluting or bare-metal stent during percutaneous coronary intervention (PCI) depends in part on the perceived likelihood of the patient developing late stent thrombosis. Noncardiac surgery and bleeding are associated with discontinuation of dual antiplatelet therapy and with increased stent thrombosis. We assessed the incidence of and predictors for subsequent noncardiac surgery and bleeding episodes in patients who had undergone PCI. Hospital discharge coding data were used to identify all adult patients undergoing public hospital PCI in New Zealand from 1996 to 2001. Hospital admissions during the ensuing 5 years were analyzed for noncardiac surgery and bleeding episodes. Eleven thousand one hundred fifty-one patients (age, 62+/-11 years; 30% women) underwent PCI, mainly for an acute coronary syndrome (73%). During the 5-year follow-up, 26% of the population underwent at least 1 noncardiac surgical procedure (23% orthopedic, 20% abdominal, 12% urologic, 10% vascular, 35% others) and 8.6% had at least 1 bleeding episode either requiring or occurring during hospitalization. Of those, half were gastrointestinal, and one quarter of bleeding events required blood transfusion. The main clinical predictors of noncardiac surgery were advanced age, previous noncardiac surgery, osteoarthritis, and peripheral vascular disease. A previous bleeding admission and age were the strongest predictors of subsequent bleeding. Noncardiac surgery is required frequently after PCI, whereas bleeding is less common. Before implanting a drug-eluting or bare-metal stent, individual patient risk stratification by the interventional cardiologist should include assessment of whether there is an increased likelihood of needing noncardiac surgery or developing bleeding.
    Circulation Cardiovascular Interventions 06/2009; 2(3):213-21. DOI:10.1161/CIRCINTERVENTIONS.108.830158 · 6.98 Impact Factor
  • Andrew C Y To, Ralph Ah Stewart
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    ABSTRACT: Optimal timing of surgery for heart valve disease relies on the accurate assessment of symptoms, lesion severity, cardiac function and the risks of disease progression. Recent studies suggest potential roles for new echocardiographic techniques, including tissue Doppler and strain imaging at rest or after exercise stress, cardiac magnetic resonance imaging and biomarkers such as B-type natriuretic peptide. These techniques may identify patients at higher risk of symptomatic deterioration or adverse clinical events, and improve the cost-effectiveness and reliability of follow-up.
    Future Cardiology 11/2008; 4(6):583-92. DOI:10.2217/14796678.4.6.583
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    ABSTRACT: A 52-year-old woman underwent successful resection of stage IIB primary mucinous adenocarcinoma of the appendix and was started on capecitabine chemotherapy. Five days into the first course, after initially experiencing diarrhea, nausea, vomiting and a transient episode of retrosternal chest pain radiating to the left scapula, she presented to the emergency department with cardiogenic shock. Electrocardiography, transthoracic echocardiography, laboratory investigation of cardiac biomarkers, coronary angiography and endomyocardial biopsy. Capecitabine-induced cardiogenic shock. Supportive treatment with dopamine, milrinone, norepinephrine (noradrenaline) and levosimendan.
    Nature Clinical Practice Cardiovascular Medicine 10/2008; 5(11):725-9. DOI:10.1038/ncpcardio1352 · 7.04 Impact Factor
  • Andrew C Y To, Irene Zeng, H Arthur Coverdale
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    ABSTRACT: Patients with severe aortic stenosis, ineligible for surgical aortic valve replacement (AVR), may instead be offered balloon aortic valvuloplasty (BAV). However, initial international enthusiasm for BAV has waned due to early restenosis and symptom recurrence. We retrospectively reviewed consecutive adult patients who had BAVs in Auckland over a 10-year period from 1997 to 2006 and recorded their clinical, echocardiographic, haemodynamic and follow-up data. Twenty-nine patients (17F) underwent 35 BAV procedures. There were 26 elderly patients (mean age 87; median logistic EuroSCORE 26%) and 3 patients requiring "bridging" prior to intended AVR at a later interval. Mean changes in left ventricular systolic pressure, aortic systolic pressure and mean gradient were -8%, +16% and -43%, respectively. In the 26 elderly patients, median time to death or recurrence of symptoms was nine months. There was a significant reduction in the number of cardiac-related admissions six months after BAV compared to six months before (p=0.02). Actuarial survival of the elderly patients at 6 months, 1 year and 2 years was 88%, 64%, 31%, respectively. Complications of BAV were 2 reversible neurological events, 2 haematomas and 1 pseudoaneurysm. Re-do BAVs in 5 patients on >or=2 occasions resulted in an improved median actuarial survival of 36 months. In our experience, BAV has a useful role in symptom palliation in severe aortic stenosis when surgical valve replacement is declined or inappropriate, and can be performed in selected patients with relatively few complications. Re-do BAVs in suitable patients may prolong symptom relief and survival.
    Heart, Lung and Circulation 09/2008; 17(6):468-74. DOI:10.1016/j.hlc.2008.06.002 · 1.17 Impact Factor

Publication Stats

136 Citations
176.01 Total Impact Points


  • 2010–2013
    • Cleveland Clinic
      Cleveland, Ohio, United States
  • 2011
    • Metropolitan Heart and Vascular Institute
      Minneapolis, Minnesota, United States
  • 2008–2010
    • Middlemore Hospital
      Окленд, Auckland, New Zealand
  • 2007–2009
    • Auckland City Hospital
      Окленд, Auckland, New Zealand