Nutrition, Metabolism & Cardiovascular Diseases (2015) 25, 931e936
Available online at www.sciencedirect.com
Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd
Coronary slow flow phenomenon: Not only low in flow rate but also in myocardial energy expenditure M.S. Cetin, E.H. Ozcan Cetin*, D. Aras, S. Topaloglu, S. Aydogdu Yuksek Ihtisas Education and Research Hospital, Cardiology Department, Ankara, Turkey Received 27 December 2014; received in revised form 4 June 2015; accepted 9 June 2015 Available online 17 June 2015
KEYWORDS Coronary slow flow phenomenon; Myocardial energy expenditure; TIMI frame count; Tensionetime index
Abstract Background and aim: Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia. The impact of this syndrome on myocardial performance has not been comprehensively evaluated. In this study, we sought to evaluate the myocardial energy expenditure (MEE) in patients with CSFP and its relationship with exercise capacity. Methods and results: A total of 64 patients (64.1% male, mean age 53.2 10.3 years) with CSFP and 64 patients (60.9% male, mean age 52.2 10.9 years) with normal coronary artery as control group were included. MEE was calculated by a validated formula that uses transthoracic echocardiography (TTE) parameters, including left ventricular circumferential end-systolic stress, stroke volume, and ejection time CSFP patients had significantly lower MEE (0.79 cal/systole 0.15 vs. 0.91 cal/systole 0.09, p < 0.001). In correlation analysis, MEE had a significant negative correlation with mean corrected TIMI frame count (mTFC) (b Z 0.523; p < 0.001) and positive correlations with metabolic equivalents (METs) (b Z 0.560; p < 0.0 01), rate pressure product (b Z 0.649; p < 0.001), and exercise duration (b Z 0.408; p < 0.001). At multivariate analysis, MEE was demonstrated as an independent predictor of CSFP (OR 1.863, CI 95% 1.485e2.338 p < 0.001). Conclusion: Myocardial energy consumption, as a calculation obtained from TTE parameters, was reduced in patients with CSFP, and it had a significant relationship with exercise capacity. Considering its significant correlation with exercise capacity, myocardial energy consumption seemed to use evaluation of myocardial performance and functional status in another cardiovascular disease. ª 2015 Elsevier B.V. All rights reserved.
Introduction Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia [1]. Current studies focus on perfusion abnormalities, including microvascular and endothelial dysfunction
* Corresponding author. Yuksek Ihtisas Education and Research Hospital, Cardiology Department Kızılay Street, Ankara 06100, Turkey. Tel.: þ90 555 720 3753. E-mail address: [email protected] (E.H. Ozcan Cetin). http://dx.doi.org/10.1016/j.numecd.2015.06.004 0939-4753/ª 2015 Elsevier B.V. All rights reserved.
[2e4]. Echocardiographic studies with different imaging modalities pointed out the impaired myocardial function in CSFP [5,6]. These functional abnormalities and anginal symptoms may derive from changes in myocardial energy metabolism. Experimental studies on rats demonstrated that the lower rate of coronary blood flow resulted in a reduced rate of adenosine triphosphate (ATP) production [7]. The impact of this syndrome on myocardial biomechanical work has not been comprehensively evaluated. The determination of myocardial energy expenditure (MEE) necessitates impractical invasive methods for
932
calculation of myocardial O2 extraction [8]. Because of this limitation in clinical use, recent development techniques offer a noninvasive estimation of myocardial mechanical work by positron emission tomography (PET), magnetic resonance imaging, and echocardiography [9]. Echocardiography-based MEE calculation has been postulated with a formula representing tensionetime index by using left ventricular circumferential end-systolic stress (cESS), stroke volume (SV), and left ventricular ejection time (ET) [10,11]. Consequently, we hypothesized that the slow coronary flow leads to changes in MEE that in turn resulted in an impairment in exercise capacity. In this study, we sought to evaluate the MEE in patients with CSFP and its relationship with exercise capacity.
Methods Study population We prospectively included a total of 128 consecutive patients undergoing coronary angiography from January 2013 to January 2014 because of the presence of symptoms of angina and/or positive stress test in our tertiary highvolume (500 coronary angiograms per month) center. The study sample was classified into two groups as with CSFP (64 patients, 64.1% male, mean age 53.2 10.3 years) and with normal coronary arteries as control group (64 patients, 60.9% male, mean age 52.2 10.9 years). CSFP was evaluated with respect to mean corrected thrombolysis in myocardial infarction (TIMI) frame count (mTFC) at least one of three main coronary arteries. We excluded patients with coronary artery disease (with any visible coronary plaque, luminal haziness, and irregularity), coronary artery anomalies (including muscular bridge, ectasia, and fistulae), coronary artery tortuosity, left ventricular ejection fraction (LVEF) < 50%, moderate-to-severe valvular disease, hematological (including anemia) or inflammatory disease, renal or hepatic insufficiency, cardiac rhythms other than sinus, and restrictive or hypertrophic cardiomyopathy. Patients having an arterial blood pressure above 140 mmHg systolic, 90 mmHg diastolic, or both, and receiving an antihypertensive therapy were categorized as hypertensive. Diabetes mellitus was defined as the use of antidiabetic drugs and a fasting blood glucose level greater than 126 mg/dl. Total cholesterol >200 mg/dl; low-density lipoprotein (LDL) > 130 mg/dl; triglycerides (TRG) > 150 mg/dl, and receiving lipid-lowering drugs were delineated as hyperlipidemia.
M.S. Cetin et al.
Coronary angiography and assessment of coronary blood flow All patients underwent coronary angiography using the standard Judkins technique with femoral or radial access. Iopromide (Ultravist 370, Schering AG, Berlin, Germany) was injected as the contrast agent 6e8 ml per each angiographic position. Care was taken to standardize the injection rate of the contrast media (2e4 ml/s). All images were recorded at 30 frames per second (frames/s). Two interventional cardiologists evaluated the angiography images and determined the flow rate of coronary arteries by using the corrected TFCs as the standardized and quantitative index of coronary flow velocity defined by Gibson et al. [12] The number of cine angiographic frames (recorded at 30 frames/s) required for the contrast to reach a predetermined distal coronary landmark was defined as TFC. The left anterior descending artery TFC was corrected by dividing by 1.7 in order to calculate the corrected TIMI frame count (cTFC). The mTFC was obtained by dividing the sum of the cTFC of the left anterior descending artery and the TFCs of the circumflex artery and right coronary artery by three. Patients with an mTFC >27 were classified as CSFP [12]. Echocardiography Two cardiologists made echocardiographic examinations, including M-mode, two-dimensional, and Doppler echocardiography with Vivid 7 Pro, GE (Horten, Norway), within 12 h after coronary angiography. LVEF was determined with modified Simpson technique. All measurements including left atrial, ventricular dimensions, posterior wall thickness (PWT), and interventricular septum thickness were measured during both systole and diastole by M-mode echocardiography in the parasternal long axis view with respect to the criteria of American Society of Echocardiography. Calculation of MEE Representing systolic tension applied to the left ventricular myocardium, cESS was extrapolated with transthoracic echocardiography (TTE) at the mid-wall from M-mode tracings, using a cylindrical model [13] with the formula of Gaasch et al., previously studied in clinical studies [14], left ventricular end-systolic diameter (LVESD), LV end-systolic PWT, and brachial systolic blood pressure (SBP), which was measured just before the echocardiographic examination:
. o n SPB ðLVESD=2Þ2 1 þ ðLVESD=2 þ PWTsÞ2 ðLVESD=2 þ PWTs=2Þ2 cESS ðGaasch’s formulaÞZ 2 LVESD þ PWTs ðLVESD=2Þ2 2
Myocardial energy expenditure and coronary slow flow phenomenon
Table 1 Baseline characteristics and laboratory parameters of groups. Variables
Patients with Control group p Value CSFP (n Z 64) (n Z 64)
Age Gender (male %) Diabetes mellitus (%) Smoking (%) Family history of CAD (%) Hypertension (%) Hyperlipidemia (%) Obesity (%) ASA (%) Beta-blocker (%) Ace inhibitor/ARB (%) Statin (%) Ca channel blocker (%) BMI (kg/m2) Glucose (mg/dl) Creatinine (mg/dl) Total cholesterol (mg/dl) LDL-C (mg/dl) HDL-C (mg/dl) Triglyceride (mg/dl) Hemoglobin (mg/dl) WBC (103 mL) mTFC
53.2 þ 10.3 41 (64.1%) 5 (7.8%) 18 (28.1%) 14 (21.9%) 17 (26.6%) 13 (20.3%) 5 (7.8%) 11 (17.2%) 11 (16%) 16 (25%) 10 (15.6%) 6 (9.4%) 24.8 3.1 106.7 þ 30.9 0.87 þ 0.18 201.5 þ 47.6 122.1 þ 41.1 45.6 þ 12.4 178.2 þ 87.3 14.8 þ 1.4 6.7 1.5 47.0 þ 18.2
52.2 þ 10.9 39 (60.9%) 6 (%9.4) 16 (25%) 12 (18.8%) 15 (%23.4) 15 (23.4%) 4 (6.2%) 16 (25%) 9 (14.4%) 15 (23.4%) 12 (18.8%) 7 (10.9%) 24.1 2.7 106.8 þ 26.9 0.87 þ 0.19 189.5 þ 42.6 119.6 þ 53.0 45.8 þ 14.7 147.9 þ 87.3 14.4 þ 1.7 6.6 1.7 17.4 þ 9.0
0.620 0.715 0.752 0.689 0.660 0.683 0.669 0.730 0.279 0.626 0.834 0.639 0.770 0.540 0.987 0.990 0.145 0.772 0.947 0.137 0.119 0.078 0.001
Data are expressed as mean standard deviation for normally distributed parametric variables and percentage for categorical variables. Bold value is statistically significant (P < 0.05). Abbreviations: ACE, angiotensin-converting enzyme; ARB angiotensin receptor blocker; ASA, acetylsalicylic acid; BMI, body mass index; Ca, calcium; CAD, coronary artery disease; CSFP, coronary slow flow phenomenon, HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; mTFC, mean corrected TIMI frame count; WBC, white blood cell.
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With the evaluation of the transaortic flow by Doppler echocardiography, we measured SV and ET as recommended by Quiñones et al. [15]. MEE per systole (MEES), a noninvasive derivative of the tensionetime index, can be calculated by multiplying cESS, ET, and SV with this validated formula [10,11]: MEES ZcESS ET SV 4:2 107 MEE per minute (MEEM) was calculated by the following formula: MEEM Z MEES Heart Rate Exercise ECG testing All patients underwent treadmill exercise testing according to the Bruce protocol within 10 days before coronary angiography. Maximum exercise performance metabolic equivalent (MET) was determined from the speed, inclination, and length of time. We assessed exercise duration, stage of Bruce protocol, and rate pressure product (RPP). Statistical analysis The continuous variables were reported as the mean standard deviation (SD) and the categorical variables were expressed as the number of patients and percentages. The comparisons between two groups were performed with Student’s t-test for continuous variables and chi-squared test or Fisher’s exact test for the categorical variables. Intraobserver and interobserver variabilities (by two independent observer) were evaluated in 20 randomly selected patients with intraclass correlation coefficient by one-way random and two-way mixed
Table 2 Echocardiographic and exercise parameters of groups. Variables
Patients with CSFP (n Z 64)
Control group (n Z 64)
p Value
LVEF (%) LVEDD (mm) LVESD (mm) e’ septal (cm/s) e’ lateral (cm/s) LV mass index (g/m2) Relative wall thickness (cm) Heart rate (/min) LVOT ET (m/s) LVOT VTI (cm) LVOT diameter (mm) Stroke volume (cc) cESS (dyne/cm2) MEE (cal/systole) MEE (cal/min) Stage of Bruce protocol Exercise duration (s) Peak exercise work (METs) Rate pressure product (103) bpm mmHg
58.4 5.1 46.3 3.7 29.4 4.2 12.0 2.2 15.9 3.5 94.8 20.6 0.40 0.09 75.4 11.1 274.6 12.5 20.7 3.7 20.0 1.7 72.4 19.4 123.5 34.0 0.91 þ 0.09 65.0 14.4 3.6 þ 0.4 493.6 86.9 9.6 1.9 23.7 4.6
59.1 4.2 46.5 3.8 28.0 4.3 12.2 2.3 16.2 3.1 97.6 21.6 0.41 0.11 77.1 9.5 280.6 12.5 21.9 2.3 20.2 0.9 79.4 14.2 134.6 18.9 0.79 þ 0.15 72.8 11.2 3.9 þ 0.5 550.6 þ 113.7 12.2 1.7 25.9 3.0
0.384 0.779 0.305 0.115 0.067 0.332 0.925 0.376 0.008 0.096 0.078 0.022 0.029
Available online at www.sciencedirect.com
Nutrition, Metabolism & Cardiovascular Diseases journal homepage: www.elsevier.com/locate/nmcd
Coronary slow flow phenomenon: Not only low in flow rate but also in myocardial energy expenditure M.S. Cetin, E.H. Ozcan Cetin*, D. Aras, S. Topaloglu, S. Aydogdu Yuksek Ihtisas Education and Research Hospital, Cardiology Department, Ankara, Turkey Received 27 December 2014; received in revised form 4 June 2015; accepted 9 June 2015 Available online 17 June 2015
KEYWORDS Coronary slow flow phenomenon; Myocardial energy expenditure; TIMI frame count; Tensionetime index
Abstract Background and aim: Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia. The impact of this syndrome on myocardial performance has not been comprehensively evaluated. In this study, we sought to evaluate the myocardial energy expenditure (MEE) in patients with CSFP and its relationship with exercise capacity. Methods and results: A total of 64 patients (64.1% male, mean age 53.2 10.3 years) with CSFP and 64 patients (60.9% male, mean age 52.2 10.9 years) with normal coronary artery as control group were included. MEE was calculated by a validated formula that uses transthoracic echocardiography (TTE) parameters, including left ventricular circumferential end-systolic stress, stroke volume, and ejection time CSFP patients had significantly lower MEE (0.79 cal/systole 0.15 vs. 0.91 cal/systole 0.09, p < 0.001). In correlation analysis, MEE had a significant negative correlation with mean corrected TIMI frame count (mTFC) (b Z 0.523; p < 0.001) and positive correlations with metabolic equivalents (METs) (b Z 0.560; p < 0.0 01), rate pressure product (b Z 0.649; p < 0.001), and exercise duration (b Z 0.408; p < 0.001). At multivariate analysis, MEE was demonstrated as an independent predictor of CSFP (OR 1.863, CI 95% 1.485e2.338 p < 0.001). Conclusion: Myocardial energy consumption, as a calculation obtained from TTE parameters, was reduced in patients with CSFP, and it had a significant relationship with exercise capacity. Considering its significant correlation with exercise capacity, myocardial energy consumption seemed to use evaluation of myocardial performance and functional status in another cardiovascular disease. ª 2015 Elsevier B.V. All rights reserved.
Introduction Coronary slow flow phenomenon (CSFP) is a miscellaneous clinical entity leading to angina-like symptoms, and electrocardiographic and scintigraphic evidence of ischemia [1]. Current studies focus on perfusion abnormalities, including microvascular and endothelial dysfunction
* Corresponding author. Yuksek Ihtisas Education and Research Hospital, Cardiology Department Kızılay Street, Ankara 06100, Turkey. Tel.: þ90 555 720 3753. E-mail address: [email protected] (E.H. Ozcan Cetin). http://dx.doi.org/10.1016/j.numecd.2015.06.004 0939-4753/ª 2015 Elsevier B.V. All rights reserved.
[2e4]. Echocardiographic studies with different imaging modalities pointed out the impaired myocardial function in CSFP [5,6]. These functional abnormalities and anginal symptoms may derive from changes in myocardial energy metabolism. Experimental studies on rats demonstrated that the lower rate of coronary blood flow resulted in a reduced rate of adenosine triphosphate (ATP) production [7]. The impact of this syndrome on myocardial biomechanical work has not been comprehensively evaluated. The determination of myocardial energy expenditure (MEE) necessitates impractical invasive methods for
932
calculation of myocardial O2 extraction [8]. Because of this limitation in clinical use, recent development techniques offer a noninvasive estimation of myocardial mechanical work by positron emission tomography (PET), magnetic resonance imaging, and echocardiography [9]. Echocardiography-based MEE calculation has been postulated with a formula representing tensionetime index by using left ventricular circumferential end-systolic stress (cESS), stroke volume (SV), and left ventricular ejection time (ET) [10,11]. Consequently, we hypothesized that the slow coronary flow leads to changes in MEE that in turn resulted in an impairment in exercise capacity. In this study, we sought to evaluate the MEE in patients with CSFP and its relationship with exercise capacity.
Methods Study population We prospectively included a total of 128 consecutive patients undergoing coronary angiography from January 2013 to January 2014 because of the presence of symptoms of angina and/or positive stress test in our tertiary highvolume (500 coronary angiograms per month) center. The study sample was classified into two groups as with CSFP (64 patients, 64.1% male, mean age 53.2 10.3 years) and with normal coronary arteries as control group (64 patients, 60.9% male, mean age 52.2 10.9 years). CSFP was evaluated with respect to mean corrected thrombolysis in myocardial infarction (TIMI) frame count (mTFC) at least one of three main coronary arteries. We excluded patients with coronary artery disease (with any visible coronary plaque, luminal haziness, and irregularity), coronary artery anomalies (including muscular bridge, ectasia, and fistulae), coronary artery tortuosity, left ventricular ejection fraction (LVEF) < 50%, moderate-to-severe valvular disease, hematological (including anemia) or inflammatory disease, renal or hepatic insufficiency, cardiac rhythms other than sinus, and restrictive or hypertrophic cardiomyopathy. Patients having an arterial blood pressure above 140 mmHg systolic, 90 mmHg diastolic, or both, and receiving an antihypertensive therapy were categorized as hypertensive. Diabetes mellitus was defined as the use of antidiabetic drugs and a fasting blood glucose level greater than 126 mg/dl. Total cholesterol >200 mg/dl; low-density lipoprotein (LDL) > 130 mg/dl; triglycerides (TRG) > 150 mg/dl, and receiving lipid-lowering drugs were delineated as hyperlipidemia.
M.S. Cetin et al.
Coronary angiography and assessment of coronary blood flow All patients underwent coronary angiography using the standard Judkins technique with femoral or radial access. Iopromide (Ultravist 370, Schering AG, Berlin, Germany) was injected as the contrast agent 6e8 ml per each angiographic position. Care was taken to standardize the injection rate of the contrast media (2e4 ml/s). All images were recorded at 30 frames per second (frames/s). Two interventional cardiologists evaluated the angiography images and determined the flow rate of coronary arteries by using the corrected TFCs as the standardized and quantitative index of coronary flow velocity defined by Gibson et al. [12] The number of cine angiographic frames (recorded at 30 frames/s) required for the contrast to reach a predetermined distal coronary landmark was defined as TFC. The left anterior descending artery TFC was corrected by dividing by 1.7 in order to calculate the corrected TIMI frame count (cTFC). The mTFC was obtained by dividing the sum of the cTFC of the left anterior descending artery and the TFCs of the circumflex artery and right coronary artery by three. Patients with an mTFC >27 were classified as CSFP [12]. Echocardiography Two cardiologists made echocardiographic examinations, including M-mode, two-dimensional, and Doppler echocardiography with Vivid 7 Pro, GE (Horten, Norway), within 12 h after coronary angiography. LVEF was determined with modified Simpson technique. All measurements including left atrial, ventricular dimensions, posterior wall thickness (PWT), and interventricular septum thickness were measured during both systole and diastole by M-mode echocardiography in the parasternal long axis view with respect to the criteria of American Society of Echocardiography. Calculation of MEE Representing systolic tension applied to the left ventricular myocardium, cESS was extrapolated with transthoracic echocardiography (TTE) at the mid-wall from M-mode tracings, using a cylindrical model [13] with the formula of Gaasch et al., previously studied in clinical studies [14], left ventricular end-systolic diameter (LVESD), LV end-systolic PWT, and brachial systolic blood pressure (SBP), which was measured just before the echocardiographic examination:
. o n SPB ðLVESD=2Þ2 1 þ ðLVESD=2 þ PWTsÞ2 ðLVESD=2 þ PWTs=2Þ2 cESS ðGaasch’s formulaÞZ 2 LVESD þ PWTs ðLVESD=2Þ2 2
Myocardial energy expenditure and coronary slow flow phenomenon
Table 1 Baseline characteristics and laboratory parameters of groups. Variables
Patients with Control group p Value CSFP (n Z 64) (n Z 64)
Age Gender (male %) Diabetes mellitus (%) Smoking (%) Family history of CAD (%) Hypertension (%) Hyperlipidemia (%) Obesity (%) ASA (%) Beta-blocker (%) Ace inhibitor/ARB (%) Statin (%) Ca channel blocker (%) BMI (kg/m2) Glucose (mg/dl) Creatinine (mg/dl) Total cholesterol (mg/dl) LDL-C (mg/dl) HDL-C (mg/dl) Triglyceride (mg/dl) Hemoglobin (mg/dl) WBC (103 mL) mTFC
53.2 þ 10.3 41 (64.1%) 5 (7.8%) 18 (28.1%) 14 (21.9%) 17 (26.6%) 13 (20.3%) 5 (7.8%) 11 (17.2%) 11 (16%) 16 (25%) 10 (15.6%) 6 (9.4%) 24.8 3.1 106.7 þ 30.9 0.87 þ 0.18 201.5 þ 47.6 122.1 þ 41.1 45.6 þ 12.4 178.2 þ 87.3 14.8 þ 1.4 6.7 1.5 47.0 þ 18.2
52.2 þ 10.9 39 (60.9%) 6 (%9.4) 16 (25%) 12 (18.8%) 15 (%23.4) 15 (23.4%) 4 (6.2%) 16 (25%) 9 (14.4%) 15 (23.4%) 12 (18.8%) 7 (10.9%) 24.1 2.7 106.8 þ 26.9 0.87 þ 0.19 189.5 þ 42.6 119.6 þ 53.0 45.8 þ 14.7 147.9 þ 87.3 14.4 þ 1.7 6.6 1.7 17.4 þ 9.0
0.620 0.715 0.752 0.689 0.660 0.683 0.669 0.730 0.279 0.626 0.834 0.639 0.770 0.540 0.987 0.990 0.145 0.772 0.947 0.137 0.119 0.078 0.001
Data are expressed as mean standard deviation for normally distributed parametric variables and percentage for categorical variables. Bold value is statistically significant (P < 0.05). Abbreviations: ACE, angiotensin-converting enzyme; ARB angiotensin receptor blocker; ASA, acetylsalicylic acid; BMI, body mass index; Ca, calcium; CAD, coronary artery disease; CSFP, coronary slow flow phenomenon, HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; mTFC, mean corrected TIMI frame count; WBC, white blood cell.
933
With the evaluation of the transaortic flow by Doppler echocardiography, we measured SV and ET as recommended by Quiñones et al. [15]. MEE per systole (MEES), a noninvasive derivative of the tensionetime index, can be calculated by multiplying cESS, ET, and SV with this validated formula [10,11]: MEES ZcESS ET SV 4:2 107 MEE per minute (MEEM) was calculated by the following formula: MEEM Z MEES Heart Rate Exercise ECG testing All patients underwent treadmill exercise testing according to the Bruce protocol within 10 days before coronary angiography. Maximum exercise performance metabolic equivalent (MET) was determined from the speed, inclination, and length of time. We assessed exercise duration, stage of Bruce protocol, and rate pressure product (RPP). Statistical analysis The continuous variables were reported as the mean standard deviation (SD) and the categorical variables were expressed as the number of patients and percentages. The comparisons between two groups were performed with Student’s t-test for continuous variables and chi-squared test or Fisher’s exact test for the categorical variables. Intraobserver and interobserver variabilities (by two independent observer) were evaluated in 20 randomly selected patients with intraclass correlation coefficient by one-way random and two-way mixed
Table 2 Echocardiographic and exercise parameters of groups. Variables
Patients with CSFP (n Z 64)
Control group (n Z 64)
p Value
LVEF (%) LVEDD (mm) LVESD (mm) e’ septal (cm/s) e’ lateral (cm/s) LV mass index (g/m2) Relative wall thickness (cm) Heart rate (/min) LVOT ET (m/s) LVOT VTI (cm) LVOT diameter (mm) Stroke volume (cc) cESS (dyne/cm2) MEE (cal/systole) MEE (cal/min) Stage of Bruce protocol Exercise duration (s) Peak exercise work (METs) Rate pressure product (103) bpm mmHg
58.4 5.1 46.3 3.7 29.4 4.2 12.0 2.2 15.9 3.5 94.8 20.6 0.40 0.09 75.4 11.1 274.6 12.5 20.7 3.7 20.0 1.7 72.4 19.4 123.5 34.0 0.91 þ 0.09 65.0 14.4 3.6 þ 0.4 493.6 86.9 9.6 1.9 23.7 4.6
59.1 4.2 46.5 3.8 28.0 4.3 12.2 2.3 16.2 3.1 97.6 21.6 0.41 0.11 77.1 9.5 280.6 12.5 21.9 2.3 20.2 0.9 79.4 14.2 134.6 18.9 0.79 þ 0.15 72.8 11.2 3.9 þ 0.5 550.6 þ 113.7 12.2 1.7 25.9 3.0
0.384 0.779 0.305 0.115 0.067 0.332 0.925 0.376 0.008 0.096 0.078 0.022 0.029
