- Email: [email protected]
Utility of immediate exercise treadmill testing in patients taking beta blockers or calcium channel blockers
Cate FJ, Roelandt JRTC, Fioretti PM. T wave normalization during dobutamine echocardiography for diagnosis of viable myocardium. Am J Cardiol 1995;75: 505–507. 8. Margonato A, Ballarotto C, Bonetti F, Cappelletti A, Sciammarella M, Cianflone D, Chierchia SL. Assessment of residual tissue viability by exercise testing in recent myocardial infarction: comparison of the electrocardiogram and myocardial perfusion scintigraphy. J Am Coll Cardiol 1992;19:948 –952. 9. Margonato A, Chierchia SL, Xuereb RG, Xuereb M, Fragasso G, Cappelletti A, Landoni C, Lucignani G, Fazio F. Specificity and sensitivity of exerciseinduced ST segment elevation for detection of residual viability: comparison with fluorodeoxyglucose and PET. J Am Coll Cardiol 1995;25:1032–1038. 10. Schneider C, Voth E, Baer F, Horst M, Wagner R, Sechtem U. QT dispersion is determined by the extent of viable myocardium in patients with chronic Q-wave myocardial infarction. Circulation 1997;96:3913–3920. 11. Al Mohammad A, Mahy IR, Buckley A, Cargill RI, Norton MY, Welch AE, Walton S. Does the presence of hibernating myocardium in patients with impaired left ventricular contraction affect QT dispersion? Am Heart J 2001;141:944 –948. 12. Bertella M, Scalise F, Lanzone A, Eriano G, Valentini R. Exercise standards (letter). Circulation 1995;92:3579 –3580. 13. Ellestad MH. Stress Testing Principles and Practice. Philadelphia: FA Davis, 1986 256 –259.
14. Lewis P, Nunan T, Dynes A, Maisey M. The use of low-dose intravenous insulin
in clinical myocardial F-18 FDG PET scanning. Clin Nucl Med 1996;21:15–18. 15. Dodge HT, Sandler H, Ballew DW, Lord JD Jr. The use of biplane angio-
cardiography for the measurement of left ventricular volume in man. Am Heart J 1960;60:762–766. 16. Yu PNG, Soffer A. Studies of electrocardiographic changes during exercise (modified double two-step test). Circulation 1952;6:183–192. 17. Elhendy A, Geleijnse A, Salustri A, van Domburg RT, Cornel JH, Arnese M, Roelandt JRTC, Fioretti PM. T wave normalization during dobutamine stress testing in patients with non-Q wave myocardial infarction. A marker of myocardial ischemia? Eur Heart J 1996;17:526 –531. 18. Mezlis NE, Parthenakis F, Kanakaraki M, Marketou M, Mavrakis H, Vardas PE. Dobutamine vs exercise-induced ST segment elevation early after Q wave myocardial infarction. Eur Heart J 2000;21:814 –822. 19. Marwick TH. ST-segment elevation after myocardial infarction: what does it mean and when is it useful? Am Heart J 1999;137:1002–1003. 20. Bodi V, Sanchis J, Llacer A, Insa L, Chorro FJ, Lopez-Merino V. ST-segment elevation on Q leads at rest and during exercise: relation with myocardial viability and left ventricular remodelling within the first 6 months after infarction. Am Heart J 1999;137:1107–1115.
Utility of Immediate Exercise Treadmill Testing in Patients Taking Beta Blockers or Calcium Channel Blockers Deborah B. Diercks,
MD,
J. Douglas Kirk, MD, Samuel D. Turnipseed, Ezra A. Amsterdam, MD
xercise electrocardiography has long been a cornerstone for evaluating patients with chest pain, E and is often the initial diagnostic test performed. 1,2
We performed immediate exercise treadmill testing (IETT) in selected patients with chest pain to stratify their risk of acute coronary syndrome.3,4 Results of previous trials have indicated that  blockers and calcium channel blockers decrease angina pectoris and can reduce blood pressure and maximal heart rate attained in patients with coronary artery disease (CAD) undergoing exercise electrocardiography.5– 8 There are conflicting data regarding the effect of these drugs on the sensitivity of the exercise test to detect CAD, and patients are often considered ineligible for diagnostic exercise testing if they are taking 1 of these agents.5,6,8 –11 This potential problem may exclude patients from an accelerated assessment in a chest pain evaluation unit, cause a delay in diagnosis, or require hospital admission for further management. The result may be the use of more expensive methods of initial evaluation such as stress echocardiography or myocardial stress scintigraphy. Our current inclusion criteria for IETT are based on the patient’s clinical stability, ability to exercise, and an interpretable electrocardiogram. We have not routinely excluded patients because of antecedent therapy with  blockers From the Divisions of Emergency Medicine and Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, School of Medicine, Sacramento, California. Dr. Diercks’ address is: Division of Emergency Medicine, University of California, Davis, Medical Center, Suite 2100, PSSB2315 Stockton Boulevard, Sacramento, California 95817. E-mail: [email protected]. Manuscript received January 31, 2002; revised manuscript received and accepted June 6, 2002.
882
©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 October 15, 2002
MD,
and
TABLE 1 Generic Medications in Study Patients Medication
No. (%)
 blocker Propranolol Atenolol Metoprolol Sotolol Nadolol
14 28 15 1 2
Total
60 (100)
Calcium channel blocker Nifedipine Amlodopine Verapamil Diltiazem
59 22 17 28
Total
(23) (47) (25) (2) (3)
(47) (18) (13) (22)
126 (100)*
*Ten patients were taking both calcium channel and  blockers.
or calcium channel blockers. Therefore, we assessed the effect of therapy with these agents on the use of IETT in stratifying the risk of acute coronary syndromes in patients presenting to the emergency department with chest pain. •••
This is a retrospective, descriptive study of all patients who underwent IETT as part of their evaluation, from October 1993 to December 1997. Patients were included in the study cohort if they reported daily use of a calcium channel blocker or  blocker. The chest pain evaluation unit is a specialized unit staffed by physicians that provide ongoing care to emergency department patients who are referred for suspected acute coronary syndromes. These patients are considered at low to moderate risk based on clin0002-9149/02/$–see front matter PII S0002-9149(02)02714-5
heart rate, rate-pressue product, metabolic equivalents of resting oxygen Study Group* Controls consumption), and the performance of Variable (n ⫽ 176) (n ⫽ 799) OR 95% CI p Value additional diagnostic testing to exclude or confirm CAD; and (3) use of IETT Age (yrs) 53 ⫾ 12 49 ⫾ 11 4† 2.0–5.8 ⬍0.001 Men 76 (44%) 432 (54%) 0.64 0.46–0.89 ⬍0.001 in predicting the presence or absence Negative IETT 86 (49%) 537 (67%) 0.46‡ 0.33–0.64 ⬍0.001 of CAD in patients taking  blockers Positive IETT 21 (12%) 103 (13%) 0.91‡ 0.56–1.5 0.73 or calcium channel blockers who have ‡ Nondiagnostic IETT 69 (39%) 159 (20%) 2.6 1.8–3.7 ⬍0.001 a diagnostic (negative or positive) ex*Patients taking  blockers and/or calcium channel blockers. ercise electrocardiogram. † Differences in means. Continuous data are presented as ‡ Unadjusted. mean ⫾ SD and were analyzed with Student’s t test. Categorical variables were analyzed with Fisher’s exact test. ical and resting electrocardiographic criteria. Eligibil- Ninety-five percent confidence intervals are given for ity criteria for IETT and results of its implementation differences in mean values for continuous data and odds have been previously described.3,5 This study was ratios for categorical variables. Multivariate logistic analapproved by our institutional review board and is part ysis was performed to identify independent predictors of the IETT result. Differences were considered significant of our ongoing quality assurance process. A single investigator reviewed the medical records of at a p value ⬍0.05. Statistical analysis was performed all eligible patients. Use of a calcium channel blocker or using Stata software (version 5.0; Stata Corporation, a  blocker was documented as present if it was noted in College Station, Texas). During the study period, 975 patients underwent the medical record or IETT report. Generic names of medications were recorded. Demographic and clinical IETT (509 men and 466 women, mean age 50 ⫾ 11 data were retrieved from the medical record and IETT years). Negative test results were found in 624 patients results were based on electrocardiographic interpretation (64%), 228 (23%) had nondiagnostic tests, and 124 of the test. Criteria for a positive (ischemic) test were (13%) had positive tests. The presence of CAD was ⱖ1.0 mm horizontal or downsloping ST-segment de- confirmed in 76 patients (7.8%) by additional diagnostic pression or elevation 80 ms after the J point. A nondi- testing. Analysis of this cohort revealed 176 patients on agnostic test was defined as one resulting in an exercise a  blocker or calcium channel blocker, thus forming the electrocardiogram without ischemic changes ⬍85% of study group. Fifty patients (28%) were taking only a  the maximal age-predicted heart rate. In addition to the blocker, 116 (66%) only a calcium channel blocker, and electrocardiographic result of IETT, other exercise test 10 (6%) were being treated with both. Generic medicaparameters recorded included percent maximal age-pre- tion names are listed in Table 1. dicted heart rate achieved, rate-pressure product (peak After adjusting for age, gender, and number of heart rate ⫻ peak systolic blood pressure), estimated cardiac risk factors, patients taking  blockers or metabolic equivalents of resting oxygen consumption calcium channel blockers (study group) were more attained, and heart rate at rest. likely to have nondiagnostic IETT (odds ratio [OR] Patients were followed from the date of the initial 2.1, 95% confidence interval [CI] 1.5 to 3.1) and less visit until December 1999. Patients with no hospital or likely to have negative IETT (OR 0.6, 95% CI 0.4 to clinic visits or those unreachable by telephone ⱖ30 0.8) than patients who were not taking these agents days after the initial visit were considered lost to (control group). Additionally, patients in the study follow-up. The performance of additional diagnostic group were older and predominantly women (Table testing, which was at the discretion of the attending 2). Further analysis revealed that patients taking  physician, was recorded for all study patients. blockers were more likely to have a nondiagnostic During the follow-up period, the presence of CAD IETT (32 of 60 [53%]) than those taking calcium was based on any of the following factors: myocardial channel blockers alone. The incidence of a nondiaginfarction, need for coronary revascularization, cardi- nostic test in patients taking calcium channel blockers ac-related death, or a positive diagnostic study iden- of the dihydropyridine class (24 of 81 [30%]) was tifying CAD. The latter included demonstration of a lower than that in patients taking nondihydropyridine reversible perfusion defect by stress myocardial scin- calcium channel blockers or  blockers (45 of 95 tigraphy, segmental wall motion abnormality by stress [47%]; OR 0.5, 95% CI 0.3 to 0.9). However, the echocardiography, or ⬎60% stenosis of a major artery incidence of nondiagnostic IETT in the dihydropyrion coronary angiography. The result of the initial dine class did exceed that in the controls (159 of 799 IETT was not used to confirm the presence of CAD. [19%]; OR 1.7, 95% CI 1 to 2.8). The primary end point for this study was the inciIn the study group, there was a significant differdence of nondiagnostic IETT in patients taking  block- ence in the heart rate at rest between those with ers or calcium channel blockers compared with patients nondiagnostic IETT (74 ⫾ 15 beats/min) and those not on these medications. Secondary end points included with diagnostic (negative or positive) IETT (82 ⫾ 18 the following: (1) relation between heart rate at rest and beats/min [difference 8], 95% CI 2.6 to 13.2). This the frequency of nondiagnostic IETT; (2) relation be- relation was not found in patients in the control group. tween exercise test parameters (maximal age-predicted Of the 69 patients with a nondiagnostic IETT, 31 TABLE 2 Clinical Characteristics of Patients and Results of IETT
BRIEF REPORTS
883
were substantial. As anticipated, patients taking  blockers had a higher incidence of nondiagnostic IETT than Confirmatory No Confirmatory patients taking any calcium channel Testing Testing blocker. This difference was even Variable (n ⫽ 31) (n ⫽ 38) Difference 95% CI p Value greater between patients taking  Men (40%) (42%) 1.01* 0.42–2.97 0.8 blockers and those taking calcium Age (yrs) 53 54 1.0 4.8–6.2 0.8 channel blockers of the dihydropyriMPHR 66% 74% 8.0 4.3–12.4 ⬍0.001 dine class. RPP 16,835 20,792 3,957 772–7,141 0.02 METs 4.4 5.0 0.6 ⫺0.9–2.2 0.4 An important goal of therapy with Cardiac events† 3 0  blockers and nondihydropyridine Diagnosed CAD 11% — calcium channel blockers is to re*Odds ratio. duce heart rate. A simple method to † Cardiac events include myocardial infarction or coronary revascularization. determine the efficacy of drug therMETs ⫽ metabolic equivalents of resting oxygen consumption; MPHR ⫽ maximal predicted heart rate; apy is to measure heart rate at rest. If RPP ⫽ rate-pressure product. patients who were receiving adequate drug therapy could be identified by the presence of bradycardia at rest, it would be expected that these patients would TABLE 4 Clinical Outcome by IETT in Patients Taking  have an attenuated heart rate response to exercise. Blockers and/or Calcium Channel Blockers This approach could be used to identify patients who 30-d would be suitable candidates for IETT. No. Follow-up Cardiac CAD Although the group with nondiagnostic tests was † IETT (%) (%) Event* Confirmed more likely to have a reduced heart rate at rest, the Negative 86 (49) 80/86 (93) 0 0 difference was minimal. Thus, there was considerable Positive 21 (12) 18/21 (86) 5 6 overlap in heart rate at rest between patients with Nondiagnostic 69 (39) 54/69 (78) 3 11 diagnostic and nondiagnostic tests; thus, this parame*Myocardial infarction or coronary revascularization. ter was not reliable in predicting the occurrence of a † Coronary artery disease confirmed by additional diagnostic testing. diagnostic IETT in individual patients. The value of a nondiagnostic exercise electrocardiogram, secondary to failure to reach an adequate heart underwent additional testing and 38 did not. The per- rate, is uncertain. Many physicians consider it necessary cent maximal age-predicted heart rate and rate-pres- to pursue further diagnostic studies, which often incorsure product were significantly lower in patients who porate pharmacologic stress with cardiac imaging when underwent further confirmatory studies (Table 3). The the initial exercise test is classified as nondiagnostic. In a occurrence of cardiac events (myocardial infarction, recent study by Gauri et al,6 the investigators suggested need for coronary revascularization) and the presence that exercise testing is still generally useful in this patient of CAD were higher in patients who underwent addi- population, but they note that diagnostic accuracy in tional testing. patients taking  blockers who fail to reach their target Most of the study group had a diagnostic IETT heart rate may be limited. It has been our practice to (negative or positive) (Table 4). Clinical follow-up for estimate the validity of such a test based on additional ⱖ30 days after the IETT was available in nearly 90% variables reflecting the degree of stress or cardiac workof patients. load incurred during the exercise test, before dismissing There were no cardiac events in those with nega- the test as inadequate to stratify the patient’s risk of tive IETT. During the follow-up period, all of the CAD. These variables include rate-pressure product and recognized cardiac events and the diagnoses of CAD metabolic equivalents of resting oxygen consumption were found in patients with either a positive IETT achieved, in addition to the percent maximal age-pre(Table 4) or in those with nondiagnostic IETT who dicted heart rate. Although widely utilized, reliance on a underwent further diagnostic evaluation (Table 3). No predetermined percent maximal age-predicted heart rate patient died during the follow-up period. to define the adequacy of exercise test performance has not been validated. The frequently quoted method for ••• Our study demonstrates that, although the incidence estimating target heart rate is 85% of maximal ageof a nondiagnostic test increases with the use of  block- predicted heart rate, calculated as 220 ⫺ age. The adeers and calcium channel blockers, IETT maintains its quacy of stress during exercise testing should not be utility. Most patients had a diagnostic test (negative or based solely on percent maximal predicted heart rate positive), indicating the value of exercise testing in a achieved, nor should the result be dichotomized into large, heterogenous population of men and women pre- negative or nondiagnostic at the cutoff point of 85%. Our senting to the emergency department with chest pain study suggests that patients who received additional disuspicious for myocardial ischemia. Clinical follow-up agnostic testing had achieved a lower amount of work revealed that patients with negative IETT had no cardiac during IETT, as demonstrated by a lower percent maxevents compared with those with positive IETT whose imal age-predicted heart rate, rate-pressure product, and cardiac event rate and subsequent diagnosis of CAD metabolic equivalents of resting oxygen consumption. TABLE 3 Predictive Value of Exercise Test Parameters in Patients With Nondiagnostic IETT Findings Taking  Blockers or Calcium Channel Blockers
884 THE AMERICAN JOURNAL OF CARDIOLOGY姞
VOL. 90
OCTOBER 15, 2002
The latter results likely influenced the physician’s decision with regard to confirmatory testing. Because of the small number of patients with CAD in this analysis, it is uncertain whether these variables are independent predictors of the presence of CAD and the need for additional testing. Exercise treadmill testing is an important component in assessing patients with chest pain, and its immediate use is a cornerstone of our chest pain evaluation unit. Our data suggest that IETT maintains its utility in stratifying these patients at risk for CAD, and excluding its use based solely on patients taking 1 of these agents is not warranted. 1. Do D, West JA, Morise A, Atwood E, Froelicher V. A consensus approach to diagnosing coronary artery disease based on clinical and exercise test data. Chest 1997;111:1742–1749. 2. Detrano R, Froelicher V. A logical approach to screening for coronary artery disease. Ann Intern Med 1987;106:846 –852. 3. Lewis WR, Amsterdam EA. Utility and safety of immediate exercise testing of
low-risk patients admitted to the hospital for suspected acute myocardial infarction. Am J Cardiol 1994;74:987–990. 4. Lewis WR, Amsterdam EA, Turnipseed S, Kirk JD. Immediate exercise testing of low risk patients with known coronary artery disease presenting to the emergency department with chest pain. Am Coll Cardiol 1999;33:1843– 1847. 5. Kirk JD, Turnipseed S, Lewis WR, Amsterdam EA. Evaluation of chest pain in low-risk patients presenting to the emergency department: the role of immediate exercise testing. Ann Emerg Med 1998;32:1–7. 6. Gauri AJ, Raxwal VK, Roux L, Fearon WF, Froelicher VF. Effects of chronotropic incompetence and beta-blocker use on the exercise treadmill test in men. Am Heart J 2001;142:136 –141. 7. Wander GS, Pasricha S, Aslam N, Avasthi G, Mahajan R, Khurana SB. Should beta-blockers be withdrawn in post-myocardial infarction patients before treadmill test? Indian Heart J 1997;49:503–506. 8. Ades PA, Thomas JD, Hanson JS, Shapiro SM, LaMountain J. Effect of metoprolol on the sub-maximal stress test performed early after acute myocardial infarction. Am J Cardiol 1987;60:963–966. 9. Ashmore RC, Corkadel LK, Green CL, Horwitz LD. Verapamil but not nifedipine impairs left ventricular function during exercise in hypertensive patients. Am Heart J 1990;119:636 –641. 10. Ho SW, McComish MJ, Taylor RR. Effect of beta-adrenergic blockade on the results of exercise testing related to the extent of coronary artery disease. Am J Cardiol 1985;55:258 –262. 11. Pellinen TJ, Virtanen KS, Valle M, Frick MH. Studies on ergometer exercise testing. II. Effect of previous myocardial infarction, digoxin, and beta-blockade on exercise electrocardiography. Clin Cardiol 1986;9:499 –507.
Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) Versus Coronary Artery Stenting for Elective Revascularization of the Left Anterior Descending Artery Ioannis Iakovou, MD, George Dangas, MD, PhD, Roxana Mehran, MD, Alexandra J. Lansky, MD, Sotiris C. Stamou, MD, Albert J. Pfister, MD, Mercedes K. C. Dullum, MD, Martin B. Leon, MD, and Paul J. Corso, MD inimally invasive direct coronary artery bypass grafting (MIDCAB) through a small left anteM rior thoracotomy without cardiopulmonary bypass has
TABLE 1 Patient Characteristics
been performed with increasing frequency in the last decade. Despite initial encouraging morbidity and mortality results,1–3 MIDCAB has raised concerns about the accuracy and quality of the anastomosis between the left internal mammary artery (LIMA) and the left anterior descending artery (LAD).4 –7 Furthermore, MIDCAB results may depend on surgical indications and selection of patients undergoing this procedure, as well as the technical experience and the learning curve.8 –10 We previously reported lower morbidity with the 1-vessel off-pump coronary artery bypass grafting (CABG) technique compared with conventional on-pump CABG11 and a very low 1-year ischemic event rate after MIDCAB.8 Although coronary stenting and MIDCAB
Age (yrs) Men Diabetes mellitus Systemic hypertension Hyperlipidemia Smoker Peripheral vascular disease Renal insufficiency LVEF mean (%) LVEF ⬎50% LVEF 35%–50% Unstable angina Prior myocardial infarction Prior stroke Body surface area (m2)
From the Cardiovascular Research Foundation, New York, New York; and Section of Cardiac Surgery, Washington Hospital Center, Washington, DC. Dr. Dangas’s address is: Lenox Hill Heart & Vascular Institute, Cardiovascular Research Foundation, 55 East 59th Street, 6th Floor, New York, New York 10022. E-mail: [email protected]. Manuscript received April 3, 2002; revised manuscript received and accepted June 10, 2002. ©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 October 15, 2002
MIDCAB (n ⫽ 119)
Stent (n ⫽ 441)
62 ⫾ 12 71% 17% 55% 72% 56% 6% 4.3% 48 ⫾ 7 77% 23% 60% 22% 6.8% 1.94 ⫾ 0.2
63 ⫾ 12 68% 22% 54% 60% 46% 11.4% 4.6% 52 ⫾ 12 85% 15% 68% 22% 6.4% 1.95 ⫾ 0.2
All p values are nonsignificant. LVEF ⫽ Left ventricular ejection fraction.
are used frequently for treating LAD lesions, the preferable approach is unknown. •••
In all, 542 consecutive patients who underwent proximal or mid-LAD lesion revascularization with either MIDCAB (n ⫽ 119) or coronary stenting (n ⫽ 0002-9149/02/$–see front matter PII S0002-9149(02)02715-7
885
14. Lewis P, Nunan T, Dynes A, Maisey M. The use of low-dose intravenous insulin
in clinical myocardial F-18 FDG PET scanning. Clin Nucl Med 1996;21:15–18. 15. Dodge HT, Sandler H, Ballew DW, Lord JD Jr. The use of biplane angio-
cardiography for the measurement of left ventricular volume in man. Am Heart J 1960;60:762–766. 16. Yu PNG, Soffer A. Studies of electrocardiographic changes during exercise (modified double two-step test). Circulation 1952;6:183–192. 17. Elhendy A, Geleijnse A, Salustri A, van Domburg RT, Cornel JH, Arnese M, Roelandt JRTC, Fioretti PM. T wave normalization during dobutamine stress testing in patients with non-Q wave myocardial infarction. A marker of myocardial ischemia? Eur Heart J 1996;17:526 –531. 18. Mezlis NE, Parthenakis F, Kanakaraki M, Marketou M, Mavrakis H, Vardas PE. Dobutamine vs exercise-induced ST segment elevation early after Q wave myocardial infarction. Eur Heart J 2000;21:814 –822. 19. Marwick TH. ST-segment elevation after myocardial infarction: what does it mean and when is it useful? Am Heart J 1999;137:1002–1003. 20. Bodi V, Sanchis J, Llacer A, Insa L, Chorro FJ, Lopez-Merino V. ST-segment elevation on Q leads at rest and during exercise: relation with myocardial viability and left ventricular remodelling within the first 6 months after infarction. Am Heart J 1999;137:1107–1115.
Utility of Immediate Exercise Treadmill Testing in Patients Taking Beta Blockers or Calcium Channel Blockers Deborah B. Diercks,
MD,
J. Douglas Kirk, MD, Samuel D. Turnipseed, Ezra A. Amsterdam, MD
xercise electrocardiography has long been a cornerstone for evaluating patients with chest pain, E and is often the initial diagnostic test performed. 1,2
We performed immediate exercise treadmill testing (IETT) in selected patients with chest pain to stratify their risk of acute coronary syndrome.3,4 Results of previous trials have indicated that  blockers and calcium channel blockers decrease angina pectoris and can reduce blood pressure and maximal heart rate attained in patients with coronary artery disease (CAD) undergoing exercise electrocardiography.5– 8 There are conflicting data regarding the effect of these drugs on the sensitivity of the exercise test to detect CAD, and patients are often considered ineligible for diagnostic exercise testing if they are taking 1 of these agents.5,6,8 –11 This potential problem may exclude patients from an accelerated assessment in a chest pain evaluation unit, cause a delay in diagnosis, or require hospital admission for further management. The result may be the use of more expensive methods of initial evaluation such as stress echocardiography or myocardial stress scintigraphy. Our current inclusion criteria for IETT are based on the patient’s clinical stability, ability to exercise, and an interpretable electrocardiogram. We have not routinely excluded patients because of antecedent therapy with  blockers From the Divisions of Emergency Medicine and Cardiovascular Medicine, Department of Internal Medicine, University of California, Davis, School of Medicine, Sacramento, California. Dr. Diercks’ address is: Division of Emergency Medicine, University of California, Davis, Medical Center, Suite 2100, PSSB2315 Stockton Boulevard, Sacramento, California 95817. E-mail: [email protected]. Manuscript received January 31, 2002; revised manuscript received and accepted June 6, 2002.
882
©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 October 15, 2002
MD,
and
TABLE 1 Generic Medications in Study Patients Medication
No. (%)
 blocker Propranolol Atenolol Metoprolol Sotolol Nadolol
14 28 15 1 2
Total
60 (100)
Calcium channel blocker Nifedipine Amlodopine Verapamil Diltiazem
59 22 17 28
Total
(23) (47) (25) (2) (3)
(47) (18) (13) (22)
126 (100)*
*Ten patients were taking both calcium channel and  blockers.
or calcium channel blockers. Therefore, we assessed the effect of therapy with these agents on the use of IETT in stratifying the risk of acute coronary syndromes in patients presenting to the emergency department with chest pain. •••
This is a retrospective, descriptive study of all patients who underwent IETT as part of their evaluation, from October 1993 to December 1997. Patients were included in the study cohort if they reported daily use of a calcium channel blocker or  blocker. The chest pain evaluation unit is a specialized unit staffed by physicians that provide ongoing care to emergency department patients who are referred for suspected acute coronary syndromes. These patients are considered at low to moderate risk based on clin0002-9149/02/$–see front matter PII S0002-9149(02)02714-5
heart rate, rate-pressue product, metabolic equivalents of resting oxygen Study Group* Controls consumption), and the performance of Variable (n ⫽ 176) (n ⫽ 799) OR 95% CI p Value additional diagnostic testing to exclude or confirm CAD; and (3) use of IETT Age (yrs) 53 ⫾ 12 49 ⫾ 11 4† 2.0–5.8 ⬍0.001 Men 76 (44%) 432 (54%) 0.64 0.46–0.89 ⬍0.001 in predicting the presence or absence Negative IETT 86 (49%) 537 (67%) 0.46‡ 0.33–0.64 ⬍0.001 of CAD in patients taking  blockers Positive IETT 21 (12%) 103 (13%) 0.91‡ 0.56–1.5 0.73 or calcium channel blockers who have ‡ Nondiagnostic IETT 69 (39%) 159 (20%) 2.6 1.8–3.7 ⬍0.001 a diagnostic (negative or positive) ex*Patients taking  blockers and/or calcium channel blockers. ercise electrocardiogram. † Differences in means. Continuous data are presented as ‡ Unadjusted. mean ⫾ SD and were analyzed with Student’s t test. Categorical variables were analyzed with Fisher’s exact test. ical and resting electrocardiographic criteria. Eligibil- Ninety-five percent confidence intervals are given for ity criteria for IETT and results of its implementation differences in mean values for continuous data and odds have been previously described.3,5 This study was ratios for categorical variables. Multivariate logistic analapproved by our institutional review board and is part ysis was performed to identify independent predictors of the IETT result. Differences were considered significant of our ongoing quality assurance process. A single investigator reviewed the medical records of at a p value ⬍0.05. Statistical analysis was performed all eligible patients. Use of a calcium channel blocker or using Stata software (version 5.0; Stata Corporation, a  blocker was documented as present if it was noted in College Station, Texas). During the study period, 975 patients underwent the medical record or IETT report. Generic names of medications were recorded. Demographic and clinical IETT (509 men and 466 women, mean age 50 ⫾ 11 data were retrieved from the medical record and IETT years). Negative test results were found in 624 patients results were based on electrocardiographic interpretation (64%), 228 (23%) had nondiagnostic tests, and 124 of the test. Criteria for a positive (ischemic) test were (13%) had positive tests. The presence of CAD was ⱖ1.0 mm horizontal or downsloping ST-segment de- confirmed in 76 patients (7.8%) by additional diagnostic pression or elevation 80 ms after the J point. A nondi- testing. Analysis of this cohort revealed 176 patients on agnostic test was defined as one resulting in an exercise a  blocker or calcium channel blocker, thus forming the electrocardiogram without ischemic changes ⬍85% of study group. Fifty patients (28%) were taking only a  the maximal age-predicted heart rate. In addition to the blocker, 116 (66%) only a calcium channel blocker, and electrocardiographic result of IETT, other exercise test 10 (6%) were being treated with both. Generic medicaparameters recorded included percent maximal age-pre- tion names are listed in Table 1. dicted heart rate achieved, rate-pressure product (peak After adjusting for age, gender, and number of heart rate ⫻ peak systolic blood pressure), estimated cardiac risk factors, patients taking  blockers or metabolic equivalents of resting oxygen consumption calcium channel blockers (study group) were more attained, and heart rate at rest. likely to have nondiagnostic IETT (odds ratio [OR] Patients were followed from the date of the initial 2.1, 95% confidence interval [CI] 1.5 to 3.1) and less visit until December 1999. Patients with no hospital or likely to have negative IETT (OR 0.6, 95% CI 0.4 to clinic visits or those unreachable by telephone ⱖ30 0.8) than patients who were not taking these agents days after the initial visit were considered lost to (control group). Additionally, patients in the study follow-up. The performance of additional diagnostic group were older and predominantly women (Table testing, which was at the discretion of the attending 2). Further analysis revealed that patients taking  physician, was recorded for all study patients. blockers were more likely to have a nondiagnostic During the follow-up period, the presence of CAD IETT (32 of 60 [53%]) than those taking calcium was based on any of the following factors: myocardial channel blockers alone. The incidence of a nondiaginfarction, need for coronary revascularization, cardi- nostic test in patients taking calcium channel blockers ac-related death, or a positive diagnostic study iden- of the dihydropyridine class (24 of 81 [30%]) was tifying CAD. The latter included demonstration of a lower than that in patients taking nondihydropyridine reversible perfusion defect by stress myocardial scin- calcium channel blockers or  blockers (45 of 95 tigraphy, segmental wall motion abnormality by stress [47%]; OR 0.5, 95% CI 0.3 to 0.9). However, the echocardiography, or ⬎60% stenosis of a major artery incidence of nondiagnostic IETT in the dihydropyrion coronary angiography. The result of the initial dine class did exceed that in the controls (159 of 799 IETT was not used to confirm the presence of CAD. [19%]; OR 1.7, 95% CI 1 to 2.8). The primary end point for this study was the inciIn the study group, there was a significant differdence of nondiagnostic IETT in patients taking  block- ence in the heart rate at rest between those with ers or calcium channel blockers compared with patients nondiagnostic IETT (74 ⫾ 15 beats/min) and those not on these medications. Secondary end points included with diagnostic (negative or positive) IETT (82 ⫾ 18 the following: (1) relation between heart rate at rest and beats/min [difference 8], 95% CI 2.6 to 13.2). This the frequency of nondiagnostic IETT; (2) relation be- relation was not found in patients in the control group. tween exercise test parameters (maximal age-predicted Of the 69 patients with a nondiagnostic IETT, 31 TABLE 2 Clinical Characteristics of Patients and Results of IETT
BRIEF REPORTS
883
were substantial. As anticipated, patients taking  blockers had a higher incidence of nondiagnostic IETT than Confirmatory No Confirmatory patients taking any calcium channel Testing Testing blocker. This difference was even Variable (n ⫽ 31) (n ⫽ 38) Difference 95% CI p Value greater between patients taking  Men (40%) (42%) 1.01* 0.42–2.97 0.8 blockers and those taking calcium Age (yrs) 53 54 1.0 4.8–6.2 0.8 channel blockers of the dihydropyriMPHR 66% 74% 8.0 4.3–12.4 ⬍0.001 dine class. RPP 16,835 20,792 3,957 772–7,141 0.02 METs 4.4 5.0 0.6 ⫺0.9–2.2 0.4 An important goal of therapy with Cardiac events† 3 0  blockers and nondihydropyridine Diagnosed CAD 11% — calcium channel blockers is to re*Odds ratio. duce heart rate. A simple method to † Cardiac events include myocardial infarction or coronary revascularization. determine the efficacy of drug therMETs ⫽ metabolic equivalents of resting oxygen consumption; MPHR ⫽ maximal predicted heart rate; apy is to measure heart rate at rest. If RPP ⫽ rate-pressure product. patients who were receiving adequate drug therapy could be identified by the presence of bradycardia at rest, it would be expected that these patients would TABLE 4 Clinical Outcome by IETT in Patients Taking  have an attenuated heart rate response to exercise. Blockers and/or Calcium Channel Blockers This approach could be used to identify patients who 30-d would be suitable candidates for IETT. No. Follow-up Cardiac CAD Although the group with nondiagnostic tests was † IETT (%) (%) Event* Confirmed more likely to have a reduced heart rate at rest, the Negative 86 (49) 80/86 (93) 0 0 difference was minimal. Thus, there was considerable Positive 21 (12) 18/21 (86) 5 6 overlap in heart rate at rest between patients with Nondiagnostic 69 (39) 54/69 (78) 3 11 diagnostic and nondiagnostic tests; thus, this parame*Myocardial infarction or coronary revascularization. ter was not reliable in predicting the occurrence of a † Coronary artery disease confirmed by additional diagnostic testing. diagnostic IETT in individual patients. The value of a nondiagnostic exercise electrocardiogram, secondary to failure to reach an adequate heart underwent additional testing and 38 did not. The per- rate, is uncertain. Many physicians consider it necessary cent maximal age-predicted heart rate and rate-pres- to pursue further diagnostic studies, which often incorsure product were significantly lower in patients who porate pharmacologic stress with cardiac imaging when underwent further confirmatory studies (Table 3). The the initial exercise test is classified as nondiagnostic. In a occurrence of cardiac events (myocardial infarction, recent study by Gauri et al,6 the investigators suggested need for coronary revascularization) and the presence that exercise testing is still generally useful in this patient of CAD were higher in patients who underwent addi- population, but they note that diagnostic accuracy in tional testing. patients taking  blockers who fail to reach their target Most of the study group had a diagnostic IETT heart rate may be limited. It has been our practice to (negative or positive) (Table 4). Clinical follow-up for estimate the validity of such a test based on additional ⱖ30 days after the IETT was available in nearly 90% variables reflecting the degree of stress or cardiac workof patients. load incurred during the exercise test, before dismissing There were no cardiac events in those with nega- the test as inadequate to stratify the patient’s risk of tive IETT. During the follow-up period, all of the CAD. These variables include rate-pressure product and recognized cardiac events and the diagnoses of CAD metabolic equivalents of resting oxygen consumption were found in patients with either a positive IETT achieved, in addition to the percent maximal age-pre(Table 4) or in those with nondiagnostic IETT who dicted heart rate. Although widely utilized, reliance on a underwent further diagnostic evaluation (Table 3). No predetermined percent maximal age-predicted heart rate patient died during the follow-up period. to define the adequacy of exercise test performance has not been validated. The frequently quoted method for ••• Our study demonstrates that, although the incidence estimating target heart rate is 85% of maximal ageof a nondiagnostic test increases with the use of  block- predicted heart rate, calculated as 220 ⫺ age. The adeers and calcium channel blockers, IETT maintains its quacy of stress during exercise testing should not be utility. Most patients had a diagnostic test (negative or based solely on percent maximal predicted heart rate positive), indicating the value of exercise testing in a achieved, nor should the result be dichotomized into large, heterogenous population of men and women pre- negative or nondiagnostic at the cutoff point of 85%. Our senting to the emergency department with chest pain study suggests that patients who received additional disuspicious for myocardial ischemia. Clinical follow-up agnostic testing had achieved a lower amount of work revealed that patients with negative IETT had no cardiac during IETT, as demonstrated by a lower percent maxevents compared with those with positive IETT whose imal age-predicted heart rate, rate-pressure product, and cardiac event rate and subsequent diagnosis of CAD metabolic equivalents of resting oxygen consumption. TABLE 3 Predictive Value of Exercise Test Parameters in Patients With Nondiagnostic IETT Findings Taking  Blockers or Calcium Channel Blockers
884 THE AMERICAN JOURNAL OF CARDIOLOGY姞
VOL. 90
OCTOBER 15, 2002
The latter results likely influenced the physician’s decision with regard to confirmatory testing. Because of the small number of patients with CAD in this analysis, it is uncertain whether these variables are independent predictors of the presence of CAD and the need for additional testing. Exercise treadmill testing is an important component in assessing patients with chest pain, and its immediate use is a cornerstone of our chest pain evaluation unit. Our data suggest that IETT maintains its utility in stratifying these patients at risk for CAD, and excluding its use based solely on patients taking 1 of these agents is not warranted. 1. Do D, West JA, Morise A, Atwood E, Froelicher V. A consensus approach to diagnosing coronary artery disease based on clinical and exercise test data. Chest 1997;111:1742–1749. 2. Detrano R, Froelicher V. A logical approach to screening for coronary artery disease. Ann Intern Med 1987;106:846 –852. 3. Lewis WR, Amsterdam EA. Utility and safety of immediate exercise testing of
low-risk patients admitted to the hospital for suspected acute myocardial infarction. Am J Cardiol 1994;74:987–990. 4. Lewis WR, Amsterdam EA, Turnipseed S, Kirk JD. Immediate exercise testing of low risk patients with known coronary artery disease presenting to the emergency department with chest pain. Am Coll Cardiol 1999;33:1843– 1847. 5. Kirk JD, Turnipseed S, Lewis WR, Amsterdam EA. Evaluation of chest pain in low-risk patients presenting to the emergency department: the role of immediate exercise testing. Ann Emerg Med 1998;32:1–7. 6. Gauri AJ, Raxwal VK, Roux L, Fearon WF, Froelicher VF. Effects of chronotropic incompetence and beta-blocker use on the exercise treadmill test in men. Am Heart J 2001;142:136 –141. 7. Wander GS, Pasricha S, Aslam N, Avasthi G, Mahajan R, Khurana SB. Should beta-blockers be withdrawn in post-myocardial infarction patients before treadmill test? Indian Heart J 1997;49:503–506. 8. Ades PA, Thomas JD, Hanson JS, Shapiro SM, LaMountain J. Effect of metoprolol on the sub-maximal stress test performed early after acute myocardial infarction. Am J Cardiol 1987;60:963–966. 9. Ashmore RC, Corkadel LK, Green CL, Horwitz LD. Verapamil but not nifedipine impairs left ventricular function during exercise in hypertensive patients. Am Heart J 1990;119:636 –641. 10. Ho SW, McComish MJ, Taylor RR. Effect of beta-adrenergic blockade on the results of exercise testing related to the extent of coronary artery disease. Am J Cardiol 1985;55:258 –262. 11. Pellinen TJ, Virtanen KS, Valle M, Frick MH. Studies on ergometer exercise testing. II. Effect of previous myocardial infarction, digoxin, and beta-blockade on exercise electrocardiography. Clin Cardiol 1986;9:499 –507.
Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) Versus Coronary Artery Stenting for Elective Revascularization of the Left Anterior Descending Artery Ioannis Iakovou, MD, George Dangas, MD, PhD, Roxana Mehran, MD, Alexandra J. Lansky, MD, Sotiris C. Stamou, MD, Albert J. Pfister, MD, Mercedes K. C. Dullum, MD, Martin B. Leon, MD, and Paul J. Corso, MD inimally invasive direct coronary artery bypass grafting (MIDCAB) through a small left anteM rior thoracotomy without cardiopulmonary bypass has
TABLE 1 Patient Characteristics
been performed with increasing frequency in the last decade. Despite initial encouraging morbidity and mortality results,1–3 MIDCAB has raised concerns about the accuracy and quality of the anastomosis between the left internal mammary artery (LIMA) and the left anterior descending artery (LAD).4 –7 Furthermore, MIDCAB results may depend on surgical indications and selection of patients undergoing this procedure, as well as the technical experience and the learning curve.8 –10 We previously reported lower morbidity with the 1-vessel off-pump coronary artery bypass grafting (CABG) technique compared with conventional on-pump CABG11 and a very low 1-year ischemic event rate after MIDCAB.8 Although coronary stenting and MIDCAB
Age (yrs) Men Diabetes mellitus Systemic hypertension Hyperlipidemia Smoker Peripheral vascular disease Renal insufficiency LVEF mean (%) LVEF ⬎50% LVEF 35%–50% Unstable angina Prior myocardial infarction Prior stroke Body surface area (m2)
From the Cardiovascular Research Foundation, New York, New York; and Section of Cardiac Surgery, Washington Hospital Center, Washington, DC. Dr. Dangas’s address is: Lenox Hill Heart & Vascular Institute, Cardiovascular Research Foundation, 55 East 59th Street, 6th Floor, New York, New York 10022. E-mail: [email protected]. Manuscript received April 3, 2002; revised manuscript received and accepted June 10, 2002. ©2002 by Excerpta Medica, Inc. All rights reserved. The American Journal of Cardiology Vol. 90 October 15, 2002
MIDCAB (n ⫽ 119)
Stent (n ⫽ 441)
62 ⫾ 12 71% 17% 55% 72% 56% 6% 4.3% 48 ⫾ 7 77% 23% 60% 22% 6.8% 1.94 ⫾ 0.2
63 ⫾ 12 68% 22% 54% 60% 46% 11.4% 4.6% 52 ⫾ 12 85% 15% 68% 22% 6.4% 1.95 ⫾ 0.2
All p values are nonsignificant. LVEF ⫽ Left ventricular ejection fraction.
are used frequently for treating LAD lesions, the preferable approach is unknown. •••
In all, 542 consecutive patients who underwent proximal or mid-LAD lesion revascularization with either MIDCAB (n ⫽ 119) or coronary stenting (n ⫽ 0002-9149/02/$–see front matter PII S0002-9149(02)02715-7
885