Parag C Patel

University of Texas Southwestern Medical Center, Dallas, Texas, United States

Are you Parag C Patel?

Claim your profile

Publications (24)120.99 Total impact


  • No preview · Article · Aug 2015 · The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Some cardiac transplant programs may upgrade listed patients to United Network for Organ Sharing (UNOS) 1A-status during the holidays. Whether more transplants actually occur during holidays is unknown. Methods: We assessed rates of single-organ heart transplantation from 2001 to 2010 for recipients age ≥18 yr using the UNOS database. Patients were stratified by transplantation during holiday (±3 d, n = 2375) and non-holiday periods (n = 16 112). Holidays included Easter/Spring break, Memorial Day, July 4th, Labor Day, Thanksgiving, and Christmas/New Years (winter holidays). Secondary analysis assessing transplant rates across seasons was also completed. Results: Donor and recipient characteristics were similar between groups. Compared with non-holidays, July 4th had higher transplant rates (5.69 vs. 5.09 transplants/d, p = 0.03) while the winter holiday had lower transplant rates (4.50 vs. 5.09 transplants/d, p < 0.01). There was a trend toward lower transplant rates for all holidays compared with non-holidays (p = 0.06). Transplant rates were significantly different across seasons with greater rates in spring and summer (p < 0.01). Conclusion: Heart transplant rates were higher during the July 4th and lower during the winter holidays. Although there was a higher likelihood of transplantation during the spring and summer seasons, upgrading patients to 1A status during most holidays may not improve their chances for transplantation.
    No preview · Article · Jun 2014 · Clinical Transplantation
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: -A noninvasive biomarker which could accurately diagnose acute rejection (AR) in heart transplant recipients could obviate the need for surveillance endomyocardial biopsies (EMB). We assessed the performance metrics of a novel highly sensitive (hs) cardiac troponin I (cTnI) assay for this purpose. -Stored serum samples were retrospectively matched to EMB in 98 cardiac transplant recipients who survived ≥ 3 months post-transplant. AR was defined as ISHLT grade 2R or higher cellular rejection, acellular rejection, or allograft dysfunction of uncertain etiology leading to treatment for presumed rejection. cTnI was measured with a hs assay (Abbott Diagnostics). Cross-sectional analyses determined the association of cTnI concentrations with rejection and ISHLT grade; and the performance metrics of cTnI for the detection of AR. Among 98 subjects, 37% had at least one rejection episode. cTnI was measured in 418 serum samples, including 35 paired to a rejection episode. cTnI concentrations were significantly higher in rejection versus nonrejection samples (median 57.1 vs. 10.2 ng/L, p < 0.0001), and increased in a graded manner with higher biopsy scores (ptrend < 0.0001). The c-statistic to discriminate AR was 0.82 (95% CI 0.76-0.88). Using a cut-point of 15 ng/L, sensitivity was 94%, specificity 60%, positive predictive value 18%, and negative predictive value 99%. -A hs-cTnI assay appears useful to "rule out" AR in cardiac transplant recipients. If validated in prospective studies, a strategy of serial monitoring with a hs-cTnI assay may offer a low-cost noninvasive strategy for rejection surveillance.
    Preview · Article · Apr 2014 · Circulation Heart Failure
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study sought to examine the frequency and hemodynamic correlates of shortness of breath when bending forward, a symptom we have termed "bendopnea." Many heart failure patients describe bendopnea such as when putting on their shoes. This symptom has not previously been characterized. We conducted a prospective study of 102 subjects with systolic heart failure referred for right-heart catheterization. Time to onset of bendopnea was measured prior to catheterization. Forty-six subjects also underwent hemodynamic assessment when sitting and bending. Hemodynamic profiles were assigned on the basis of whether pulmonary capillary wedge pressure (PCWP) was ≥22 mm Hg and cardiac index (CI) was ≤2.2 l/min/m(2). Bendopnea was present in 29 of 102 (28%) subjects with median (25th, 75th percentiles) time to onset of 8 (7, 11) seconds. Subjects with bendopnea had higher supine right atrial pressure (RAP) (p = 0.001) and PCWP (p = 0.0004) than those without bendopnea but similar CI (p = 0.2). RAP and PCWP increased comparably in subjects with and without bendopnea when bending, but CI did not change. In those with, versus without, bendopnea, there was more than a 3-fold higher frequency of a supine hemodynamic profile consisting of elevated PCWP with low CI (55% vs. 16%, respectively, p < 0.001) but no association with a profile of elevated PCWP with normal CI (p = 0.95). Bendopnea is mediated via a further increase in filling pressures during bending when filling pressures are already high, particularly if CI is reduced. Awareness of bendopnea should improve noninvasive assessment of hemodynamics in subjects with heart failure.
    No preview · Article · Feb 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sirolimus is used in cardiac transplant recipients to prevent rejection, progression of cardiac allograft vasculopathy, and renal dysfunction. However, sirolimus has many potential side effects and its tolerability when used outside of clinical trials is not well established. We describe a decade of experience with sirolimus in cardiac transplant recipients at our institution. We retrospectively reviewed records of all adult cardiac transplant recipients living between September 1999 and February 2010 (n = 329) and identified 67 patients (20%) who received sirolimus. The indications for sirolimus were cardiac allograft vasculopathy (67%), renal dysfunction (25%), rejection (4%), and intolerability of tacrolimus (3%). One-third of patients discontinued sirolimus at a median (25th, 75th percentiles) of 0.9 (0.2, 1.6) yr of duration. Over 70% of subjects experienced an adverse event attributed to sirolimus. Adverse events were associated with higher average sirolimus levels (9.1 ng/mL vs. 7.1 ng/mL, p = 0.004). We conclude that sirolimus is frequently used in cardiac transplant recipients (20%) and commonly causes side effects, often necessitating discontinuation. Higher average sirolimus levels were associated with adverse events, suggesting that tolerability may improve if levels are maintained within the lower end of the current therapeutic range; however, the improvement in tolerability would need to be balanced with the potential for decreased efficacy.
    No preview · Article · Nov 2013 · Clinical Transplantation
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To test a multidisciplinary approach to reduce heart failure (HF) readmissions that tailors the intensity of care transition intervention to the risk of the patient using a suite of electronic medical record (EMR)-enabled programmes. A prospective controlled before and after study of adult inpatients admitted with HF and two concurrent control conditions (acute myocardial infarction (AMI) and pneumonia (PNA)) was performed between 1 December 2008 and 1 December 2010 at a large urban public teaching hospital. An EMR-based software platform stratified all patients admitted with HF on a daily basis by their 30-day readmission risk using a published electronic predictive model. Patients at highest risk received an intensive set of evidence-based interventions designed to reduce readmission using existing resources. The main outcome measure was readmission for any cause and to any hospital within 30 days of discharge. There were 834 HF admissions in the pre-intervention period and 913 in the post-intervention period. The unadjusted readmission rate declined from 26.2% in the pre-intervention period to 21.2% in the post-intervention period (p=0.01), a decline that persisted in adjusted analyses (adjusted OR (AOR)=0.73; 95% CI 0.58 to 0.93, p=0.01). In contrast, there was no significant change in the unadjusted and adjusted readmission rates for PNA and AMI over the same period. There were 45 fewer readmissions with 913 patients enrolled and 228 patients receiving intervention, resulting in a number needed to treat (NNT) ratio of 20. An EMR-enabled strategy that targeted scarce care transition resources to high-risk HF patients significantly reduced the risk-adjusted odds of readmission.
    Full-text · Article · Jul 2013 · BMJ quality & safety
  • [Show abstract] [Hide abstract]
    ABSTRACT: Guidelines recommend that patients with new-onset systolic heart failure (HF) receive a trial of medical therapy before an implantable cardiac defibrillator (ICD). This strategy allows for improvement of left ventricular ejection fraction (LVEF), thereby avoiding an ICD, but exposes patients to risk of potentially preventable sudden cardiac death during the trial of medical therapy. We reviewed a consecutive series of patients with HF of <6 months duration with a severely depressed LVEF (<30%) evaluated in a HF clinic (N = 224). The ICD implantation was delayed with plans to reassess LVEF approximately 6 months after optimization of β-blockers. Mortality was ascertained by the National Death Index. Follow-up echocardiograms were performed in 115 of the 224 subjects. Of these, 50 (43%) had mildly depressed or normal LVEF at follow-up ("LVEF recovery") such that an ICD was no longer indicated. In a conservative sensitivity analysis (using the entire study cohort, whether or not a follow-up echocardiogram was obtained, as the denominator), 22% of subjects had LVEF recovery. Mortality at 6, 12, and 18 months in the entire cohort was 2.3%, 4.5%, and 6.8%, respectively. Of 87 patients who tolerated target doses of β-blockers, only 1 (1.1%) died during the first 18 months. Patients with new-onset systolic HF have both a good chance of LVEF recovery and low 6-month mortality. Achievement of target β-blocker dose identifies a very low-risk population. These data support delaying ICD implantation for a trial of medical therapy.
    No preview · Article · Sep 2012 · American heart journal
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: AimsLeft atrial (LA) structural and functional abnormalities may be subclinical phenotypes, which identify individuals at increased risk of adverse outcomes.Methods and resultsMaximum LA volume (LAmax) and LA emptying fraction (LAEF) were measured via cardiac magnetic resonance imaging in 1802 participants in the Dallas Heart Study. The associations of LAEF and LAmax indexed to body surface area (LAmax/BSA) with traditional risk factors, natriuretic peptide levels, and left ventricular (LV) structure [end-diastolic volume (EDV) and concentricity(0.67) (mass/EDV(0.67))] and function (ejection fraction) were assessed using linear regression analysis. The incremental prognostic value of LAmax/BSA and LAEF beyond traditional risk factors, LV ejection fraction, and LV mass was assessed using the Cox proportional-hazards model. Both increasing LAmax/BSA and decreasing LAEF were associated with hypertension and natriuretic peptide levels (P < 0.05 for all). In multivariable analysis, LAmax/BSA was most strongly associated with LV end-diastolic volume/BSA, while LAEF was strongly associated with LV ejection fraction and concentricity(0.67). During a median follow-up period of 8.1 years, there were 81 total deaths. Decreasing LAEF [hazard ratio (HR) per 1 standard deviation (SD) (8.0%): 1.56 (1.32-1.87)] but not increasing LAmax/BSA [HR per 1 SD (8.6 mL/m(2)): 1.14 (0.97-1.34)] was independently associated with mortality. Furthermore, the addition of LAEF to a model adjusting Framingham risk score, diabetes, race, LV mass, and ejection fraction improved the c-statistic (c-statistics: 0.78 vs. 0.77; P < 0.05, respectively), whereas the addition of LAmax/BSA did not (c-statistics: 0.76, P = 0.20).Conclusion In the general population, both LAmax/BSA and LAEF are important subclinical phenotypes but LAEF is superior and incremental to LAmax/BSA.
    Preview · Article · Jul 2012 · European Heart Journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: Sirolimus is an immunosuppressive agent increasingly used in cardiac transplant recipients in the setting of allograft vasculopathy or worsening renal function. Recently, sirolimus has been associated with increased risk of venous thromboembolism (VTE) in lung transplant recipients. To investigate whether this association is also present in cardiac transplant recipients, we retrospectively reviewed the charts of 67 cardiac transplant recipients whose immunosuppressive regimen included sirolimus and 134 matched cardiac transplant recipients whose regimen did not include sirolimus. Rates of VTE were compared. Multivariable Cox proportional hazards models tested the association of sirolimus use with VTE. A higher incidence of VTE was seen in patients treated with vs. without sirolimus (8/67 [12%] vs. 9/134 [7%], log-rank statistic: 4.66, p = 0.03). Lower body mass index (BMI) and total cholesterol levels were also associated with VTE (p < 0.05). The association of sirolimus with VTE persisted when adjusting for BMI (hazard ratio [95% confidence interval]: 2.96 [1.13, 7.75], p = 0.03) but not when adjusting for total cholesterol (p = 0.08). These data suggest that sirolimus is associated with an increased risk of VTE in cardiac transplant recipients, a risk possibly mediated through comorbid conditions. Larger, more conclusive studies are needed. Until such studies are completed, a heightened level of awareness for VTE in cardiac transplant recipients treated with sirolimus appears warranted.
    No preview · Article · Jul 2012 · Clinical Transplantation
  • [Show abstract] [Hide abstract]
    ABSTRACT: The term New York Heart Association (NYHA) class IIIB has been used increasingly in clinical medicine, including as an inclusion criteria for many clinical trials assessing left ventricular assist devices (LVADs). Indeed, NYHA class IIIB is incorporated in the Food and Drug Administration's approved indication for the Heartmate II. However, on review of the medical literature, we found that there is no consensus definition of NYHA class IIIB. Until the ambiguity is resolved, we suggest that this designation not be used in clinical practice or by investigators leading clinical trials assessing therapies which convey substantial risk to patients and therefore require clarity in describing the enrolled patient population. With ongoing improvements in LVADs, this therapy will increasingly be considered in patients less sick than those who require inotropic support, providing urgency to establish a consensus system of classifying such patients who nevertheless fall within the spectrum of advanced heart failure. Herein we propose a modification of the standard NYHA classification system which can be used to fill this void.
    No preview · Article · May 2012 · Journal of cardiac failure

  • No preview · Article · Mar 2012 · Circulation Heart Failure
  • [Show abstract] [Hide abstract]
    ABSTRACT: Whether concentric left ventricular (LV) hypertrophy (LVH) is a common precursor to depressed LV ejection fraction (EF) in humans is uncertain. From 1992 through 1994, 555 patients at our institution underwent echocardiography and had LVH (posterior or septal wall thickness ≥1.3 cm or concentric LVH noted) and normal LVEF. Of these, 220 (40%) had a follow-up assessment of LVEF by December 2008. The duration of follow-up was classified as short (≤7.5 years) or long (>7.5 years) term. The primary outcome was the development of a qualitatively depressed LVEF (mildly, moderately, or severely depressed). After a median follow-up of 7.5 years, 20% of the patients with concentric LVH developed a low LVEF. A low LVEF developed in 13% of subjects without interval myocardial infarction (MI) and 50% of subjects with interval MI during short-term follow-up (p <0.005). A low LVEF developed in 20% of subjects without interval MI and 44% of subjects with interval MI during long-term follow-up (p = 0.01). Of the subjects who developed a reduced LVEF, the relative wall thickness (median 0.5, 25th to 75th percentile 0.4 to 0.6) at follow-up was consistent with a concentric, rather than eccentric, phenotype. In conclusion, in patients with concentric LVH, the transition from a normal LVEF to a low LVEF was relatively infrequent (20%) after long-term follow-up in the absence of interval MI and usually did not result in a change in the LV geometry from a concentric to an eccentric phenotype.
    No preview · Article · Jul 2011 · The American journal of cardiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Identifying asymptomatic individuals with American Heart Association/American College of Cardiology stage B heart failure (HF) in the population is an important step to prevent the development of symptomatic HF. The comparative utility of 2 screening strategies (biomarkers vs risk scores) in identifying prevalent stage B HF is unknown. Participants 30 to 65 years old without symptomatic HF in the Dallas Heart Study who had a cardiac magnetic resonance imaging were included (n = 2,277). Stage B HF (n = 284) was defined by left ventricular (LV) hypertrophy, reduced LV ejection fraction, or prior myocardial infarction. We compared the utility of 2 risk scores (Health Aging and Body Composition HF risk score and the Framingham Heart Failure risk score) with B-type natriuretic peptide (BNP) and N-terminal pro-BNP in identifying stage B HF using logistic regression. Depending upon the method of indexing LV mass (body surface area, fat-free mass, or height(2.7)), the c-statistic for the Health Aging and Body Composition HF risk score (0.73, 0.75, and 0.64, respectively) was greater than that for BNP (0.62, 0.70, and 0.57, respectively) and N-terminal pro-BNP (0.62, 0.69, and 0.56, respectively) (P < .01 for all). These findings were similar for the Framingham Heart Failure risk score except when LV mass was indexed to fat-free mass. Addition of natriuretic peptide levels to the risk scores resulted in a modest but significant improvement in discrimination of stage B HF (Δ c-statistic, 0.01-0.03, P < .05 for all). Screening for stage B HF in the population is enhanced when natriuretic peptides are measured in addition to, rather than in place of, traditional risk scores.
    No preview · Article · May 2011 · American heart journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although risk factors for left ventricular (LV) hypertrophy in the native heart are well known, as is its association with increased risk of adverse outcomes, such information is poorly defined in heart transplant (HTx) recipients. We determined whether increased LV mass and concentricity (mass/volume) were associated with death in patients after HTx. Between May 2003 and May 2006, 140 HTx recipients underwent cardiac magnetic resonance imaging (MRI). Clinical characteristics associated with increased LV mass were determined. Cox proportional hazard models were constructed to assess the relationship of LV mass and concentricity with death. MRIs were acquired a median of 6.0 years after transplant. The top quartile of indexed LV mass and concentricity were 35.8 g/m(2.7) or higher and 1.5 g/ml or higher, respectively. History of rejection (odds ratio [OR], 5.9; 95% confidence interval [CI], 2.1-16.4; p < 0.01), diabetes (OR, 3.3; 95% CI, 1.3-8.2; p = 0.01), and post-transplant year of MRI acquisition (OR, 1.2; 95% CI, 1.1-1.4; p < 0.01) were associated with the top quartile of LV mass in multivariable models. LV mass and concentricity were independently associated with cardiovascular death (hazard risk [HR], 1.11 per g/m;(2.7) HR, 10.1 per g/ml, p ≤ 0.01, respectively). LV concentricity was independently associated with all-cause mortality (HR, 4.4 per g/ml, p < 0.01). A history of rejection and diabetes are associated with increased LV mass. Increased LV mass, particularly of a concentric phenotype, is an independent risk factor for cardiovascular and all-cause mortality after HTx.
    No preview · Article · Dec 2010 · The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation

  • No preview · Article · Aug 2010 · Journal of Cardiac Failure
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To examine whether individuals with low short-term risk of coronary heart disease but high lifetime predicted risk of cardiovascular disease (CVD) have greater prevalence of left ventricular (LV) hypertrophy and increased aortic wall thickness (AWT) than those with low short-term and low lifetime risk. Lifetime risk prediction can be used for stratifying individuals younger than 50 years of age into 2 groups: low short-term/high lifetime and low short-term/low lifetime predicted risk of CVD. Individuals with low short-term/high lifetime risk have a greater burden of subclinical atherosclerosis as measured by coronary artery calcium and carotid intima-media thickness. However, >75% of individuals with low short-term/high lifetime risk do not have detectable coronary artery calcium, suggesting the presence of alternative subclinical abnormalities. We stratified 1,804 Dallas Heart Study subjects between the ages of 30 and 50 years who had cardiac magnetic resonance into 3 groups: low short-term (<10% 10-year risk of coronary heart disease)/low lifetime predicted risk (<39% lifetime risk of CVD), low short-term (<10%)/high lifetime risk (> or =39%), and high short-term risk (> or =10%, prevalent diabetes, or previous stroke, or myocardial infarction). In those with low short-term risk, we compared measures of LV hypertrophy and AWT between those with low versus high lifetime risk. Subjects with low short-term/high lifetime risk compared with those with low short-term/low lifetime risk had increased LV mass (men: 95 +/- 17 g/m(2) vs. 90 +/- 12 g/m(2) and women: 75 +/- 14 g/m(2) vs. 71 +/- 10 g/m(2), respectively; p < 0.001 for both). LV concentricity (mass/volume), wall thickness, and AWT were also significantly greater in those with high lifetime risk in this comparison (p < 0.001 for all), but LV end-diastolic volume was not (p > 0.3). These associations persisted among participants without detectable coronary artery calcium. Among individuals 30 to 50 years of age with low short-term risk, a high lifetime predicted risk of CVD is associated with concentric LV hypertrophy and increased AWT.
    Preview · Article · Jun 2010 · JACC. Cardiovascular imaging
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Health ABC Heart Failure score has recently been shown to predict 5-year risk of incident heart failure in the elderly. We tested whether this risk score is associated with subclinical phenotypes of heart failure in a younger population. We stratified participants in the Dallas Heart Study aged 30 to 65 years who had a cardiac magnetic resonance imaging and no self-reported history of heart failure or cardiomyopathy into 4 previously defined Health ABC Heart Failure risk groups: low (<5%), average (5%-10%), high (10%-20%), and very high (>20% risk for heart failure within 5 years). We compared left ventricular (LV) structural and functional parameters and levels of B-type natriuretic peptide (BNP) and N-terminal proBNP among the 4 groups. In the study cohort (N = 2,540), the percentage of subjects in the low-, average-, high-, and very high risk groups was 78%, 15%, 6%, and 1%, respectively. Indexed LV mass (80 +/- 15 vs 90 +/- 20 vs 95 +/- 25 vs 116 +/- 41 g/m(2)), concentricity (1.6 +/- 0.3 vs 1.8 +/- 0.4 vs 2.0 +/- 0.5 vs 2.2 +/- 0.7 g/mL), median BNP (2.8 vs 3.7 vs 4.9 vs 7.5 pg/mL) and N-terminal proBNP (26 vs 30 vs 40 vs 58 pg/mL), and prevalent LV systolic dysfunction and LV hypertrophy progressively increased across risk groups (P < .001 for all) independent of gender or method of indexing LV mass. The Health ABC Heart Failure score was associated with subclinical cardiac structural changes in the general population 30 to 65 years of age, suggesting that it may be a valid tool for identification of young individuals at increased risk for heart failure.
    No preview · Article · May 2010 · American heart journal
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this report, a case is presented of a patient with advanced heart failure who had asymptomatic pancreatic gout, which masqueraded as metastatic pancreatic cancer. This unusual presentation of gout was important to recognize, as the presence of a pancreatic cancer would have precluded cardiac transplantation in an otherwise suitable candidate.
    No preview · Article · Oct 2009 · The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation
  • [Show abstract] [Hide abstract]
    ABSTRACT: Patients with muscular dystrophy are at risk of developing a dilated cardiomyopathy and can progress to advanced heart failure. At present, it is not known whether such patients can safely undergo cardiac transplantation. This was a retrospective review of the Cardiac Transplant Research Database, a multi-institutional registry of 29 transplant centers in the United States, from the years 1990 to 2005. The post-cardiac transplant outcomes of 29 patients with muscular dystrophy were compared with 275 non-muscular dystrophy patients with non-ischemic cardiomyopathy, matched for age, body mass index, gender, and race. Becker's muscular dystrophy was present in 52% of the patients. Survival in the muscular dystrophy patients was similar to the controls at 1 year (89% vs 91%; p = 0.5) and at 5 years (83% vs 78%; p = 0.5). The differences in rates of cumulative infection, rejection, or allograft vasculopathy between the 2 groups were not significant (p > 0.5 for all comparisons). Recognizing the limitations of the present investigation (ie, selection bias and data lacking in the functional capacity of the muscular dystrophy patients), the current study suggests that the clinical outcomes after cardiac transplantation in selected patients with muscular dystrophy are similar to those seen in age-matched patients with non-ischemic cardiomyopathy.
    No preview · Article · Oct 2009 · The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation

  • No preview · Article · Aug 2009 · Journal of Cardiac Failure

Publication Stats

298 Citations
120.99 Total Impact Points

Institutions

  • 2008-2015
    • University of Texas Southwestern Medical Center
      • • Division of Cardiology
      • • Department of Internal Medicine
      Dallas, Texas, United States
  • 2012
    • Parkland Memorial Hospital
      Dallas, Texas, United States
  • 2011-2012
    • University of Texas at Dallas
      Richardson, Texas, United States
  • 2009
    • University of Northwestern – St. Paul
      Saint Paul, Minnesota, United States