Relation of Silent Myocardial lschemia After Coronary Artery Bypass Grafting to Angiographic Completeness of Revascularization and Long-Term Prognosis Harold L. Kennedy, MD, MPH, Sondra M. Seiler, BA, Michael K. Sprague, Sharon M. Homan, PhD, James A. Whitlock, MPH, Morton J. Kern, MD, Michel G. Vandormael, MD, Hendrick B. Barner, MD, John E. Codd, MD, and Vallee L. Willman, MD, with the technical assistance of Debra Lyyski
The prevabnce and characteristks of silent myocardial kdremi as detectexl by 24.hour *-OgraphY STpmspedvdyassessedinS4 patbnts exL;cined early (1 to 3 months) and 164
patbnts examined late (12 months) after cammy artery byPass grafthg
(CABG), and followed for a
meanof46fll(range4to62)months.Tharehtbn of aunbulatory elechadbgraptdc sibnt ischefnia to evtdence of comptets of revasa~lartzation as defined by card&c angiagraphy pe&m~I 1 ad 12 mamths after CABG, and to prognosis by fokw-up of advent dinkal events was amdyzed. Sibnt isdmnii was detected earty in 26% (19 of
94)andhtcin27%(50of184)of~,and showed a mean frequemy of episodes ranghg fram 6to10episodes/24hourswithamean&mtiw ranging from 15 to 23 minubs. The circadian disasigniftcuntpsakof triiofepkoder~ . =I$? dwhg the period of 6 A.M. to selamby peak between 6 P.M. and ldbight (p 50% were also recorded. Discrepancies were adjudicated by consensus review with 2 cardiologists. Myocardial revascularization was considered angiographically complete according to the following criteria: all proximal sections of major coronary arteries and branches with significant stenoses were grafted, all grafts and anastomotic sites were patent and no significant stenosesdistal to graft insertions were detected by angiography.‘O Fottowup dinkal evaluat&n: All patients were followed prospectively by clinic visit or telephone contact for the occurrenceof angina, myocardial infarction, revascularization (percutaneous coronary angioplasty or repeat CABG) and death. Angina was defined as a typical history of chest pain accompaniedby objective evil-HE AMERICAN JOURNAL OF CARDIOLOGY JANUARY 1. 1990
15
TABLE I Clinical Characteristics of Patients Examined Early (1 to 3 Months) and Late (12 Months) After CABG Surgery With and Wtthout Evidence of Silent Ischemia Detected by Ambulatory Electrocardiography Early After CABG
Characteristics Age 66 Sex: M/F Diabetes (n) Hypertension (n) Current smoking(n) Prior MI (n) Calcium antagonists (n) ,9Mockers (n) Nitrates (n) Antiplatelet therapy (n) Mean cholesterol (mg/dl) Mean triglycerides (mg/dl) Angina before CABG (n) Class I to II class Ill to IV Angina after CABG (n) class I to II Class III to IV ’ p 70% stenoses),ejection fraction, number of grafts, number of anastomotic sites, number of grafts occluded/patient, number of anastomotic sites occluded/patient, number of grafted arteries with distal stenosis (70 and 50%),
number of ungrafted native arteries with significant stenosis (70 and 50%), ventricular wall motion score,New York Heart Association class (before CABG), presence of ST-segment depressionand total ischemic duration (60 minutes). Statistical significance was acceptedat p cO.05. RESULTS
Uinical drsracteristies: Ambulatory ECG examination of the 94 patients examined early after CABG detected 19 (20%) patients with transient ST depression,8 (9%) patients with transient ST elevation and 67 (71%) patients without ST-segment changes. Similarly, of 184 patients examined late after CABG, 50 (27%) patients showedtransient ST depression,13 (7%) patients showed transient ST elevation and 121 (66%) patients had no ST-segment changes. All patients with ST-segment depressionwere asymptomatic, with the exception of 2 patients in the early group, and 1 patient in the late group who also had typical angina. The clinical characteristics of 86 early and 171 late patients with and without silent ischemia detected after CABG are listed in Table 1. No significant differences were found betweenpatients with or without silent ischemia except for the increased use of nitrates in silent ischemia patients in the late group. Significantly (p
2 mm over baseline. Analysis of the data with or without inclusion of these patients was not significantly different, and their findings were included. Virtually all episodes (99%) of transient ST-segment depressiondetected were asymptomatic. The circadian distribution of the time of occurrence of number of episodesand minutes of ischemicduration are listed in Figure 1. The frequency of ischemic episodessignificantly peakedin the morning hours between 6 A.M. and 12 noon, and a second modal peak was ob servedbetween6 P.M.and midnight in patients both early and late after CABG (analysis of variance: early, p =
Early Posti s$BG Group 12 24 u .g 20 8
16
h
150 175
D”, $ -9 2 Ee
:: 75 50
5 B
“0 12 b 8 G4 a 2
.2
250 22s 200
h ’
12 3 -,-L--p-
6
9
12
3
6
9
’
12 3 6 9 -am-L-pm-----J
12
3
6
9
Time of Day
Time of Day
Late Post - CABG Group (N=SO) $
24
450 500
3 .Yn
20
.B * 400 f-3 v) Y 350 ‘0 $300
w 3 k
16 12 8
iIn .I; z ;
Pp ‘O” rem
z4 Z’O
12 3 -m--p-
6
9
12
3
6
9
Time of Day A. FtGuRE Me-
1. Hady
250 200 150
~oftoWnunbaot~(A)rdtoW~otST~~(B)daeckdhlS emty(1to3momths)mdSOpatbmtsexm&md
’
12 I
3
12
3
6
9
Time of Day
H Symptomatic
0
6 9 am--pm-
B.
Silent
late(12madhs)attarczorawy
=-Ybl=-Pmfm
mw.
THE AMERICAN
JOURNAL
OF CARDIOLOGY
JANUARY
1. 1990
17
TA8l.E III Angiographic and Hemodynamic Characteristics of Patients Examined Early (1 to 3 Months) and Late (12 Months) After CABG With and Without Evidence of Silent lschemia Detected by Ambulatory Electrocardiography Late After CABG
Early After CABG
Characteristics No. of vessels with >70% stenosis* 1 2 3 Left main 250% No. of grafts 0 SVG 1 SVG 2 SVG 3 SVG 4 SVG 1%
2seq 1Y 1 IMA 2 IMA 1 IMASeq Mean grafts/pt Mean anastomotic sites/pt EF before CABG’ EF after CABG No. of patients EF 240 EF 40 LVEDP (mm Hg) before CAffi LVEDP (mm Hg) after CABG
Silent lschemia (n = 19)
No lschemia (n = 67)
Silent lschemla (n = 50)
2 6 11 2
10 33 24 5
5 25 20 7
1 12 5 1 0 9 2 2 7 0 2 2.7 f 1.0 3.6 f 0.8 66f12 68f14
11 32 21 2 1 33 9 5 18 2 11 2.7 f 3.7 f 64f 67f
8 28 9 5 0 27 4 6 16 1 6 2.6 f 3.6 f 64f 64*
17 0 13f5 lOf5
60
l Lefl man &ease inch&d as P-vessel disease. and 2 patents mung CABG - corcwwy arlety bypass grafting: EF - epctm lracl~on: IMA graft; SVG = &ated saphenous van &t: Y - Y-graft (2 Iambs).
2 13f7 llf6
13 47 59 20
48 2 13f8 llf5
fn the grcup late after CABG because of 50% steoov~;
0.7 1.0 15 14
12 48’ 519 8 2 54 7 6 41 4 20 2.7 f 0.6 3.6 f 1.0 66f15 65f13 117 4 12f6 11 f4
’ not all patients had EF: ’ p cO.05: 5 p
The prevabnce and characteristks of silent myocardial kdremi as detectexl by 24.hour *-OgraphY STpmspedvdyassessedinS4 patbnts exL;cined early (1 to 3 months) and 164
patbnts examined late (12 months) after cammy artery byPass grafthg
(CABG), and followed for a
meanof46fll(range4to62)months.Tharehtbn of aunbulatory elechadbgraptdc sibnt ischefnia to evtdence of comptets of revasa~lartzation as defined by card&c angiagraphy pe&m~I 1 ad 12 mamths after CABG, and to prognosis by fokw-up of advent dinkal events was amdyzed. Sibnt isdmnii was detected earty in 26% (19 of
94)andhtcin27%(50of184)of~,and showed a mean frequemy of episodes ranghg fram 6to10episodes/24hourswithamean&mtiw ranging from 15 to 23 minubs. The circadian disasigniftcuntpsakof triiofepkoder~ . =I$? dwhg the period of 6 A.M. to selamby peak between 6 P.M. and ldbight (p 50% were also recorded. Discrepancies were adjudicated by consensus review with 2 cardiologists. Myocardial revascularization was considered angiographically complete according to the following criteria: all proximal sections of major coronary arteries and branches with significant stenoses were grafted, all grafts and anastomotic sites were patent and no significant stenosesdistal to graft insertions were detected by angiography.‘O Fottowup dinkal evaluat&n: All patients were followed prospectively by clinic visit or telephone contact for the occurrenceof angina, myocardial infarction, revascularization (percutaneous coronary angioplasty or repeat CABG) and death. Angina was defined as a typical history of chest pain accompaniedby objective evil-HE AMERICAN JOURNAL OF CARDIOLOGY JANUARY 1. 1990
15
TABLE I Clinical Characteristics of Patients Examined Early (1 to 3 Months) and Late (12 Months) After CABG Surgery With and Wtthout Evidence of Silent Ischemia Detected by Ambulatory Electrocardiography Early After CABG
Characteristics Age 66 Sex: M/F Diabetes (n) Hypertension (n) Current smoking(n) Prior MI (n) Calcium antagonists (n) ,9Mockers (n) Nitrates (n) Antiplatelet therapy (n) Mean cholesterol (mg/dl) Mean triglycerides (mg/dl) Angina before CABG (n) Class I to II class Ill to IV Angina after CABG (n) class I to II Class III to IV ’ p 70% stenoses),ejection fraction, number of grafts, number of anastomotic sites, number of grafts occluded/patient, number of anastomotic sites occluded/patient, number of grafted arteries with distal stenosis (70 and 50%),
number of ungrafted native arteries with significant stenosis (70 and 50%), ventricular wall motion score,New York Heart Association class (before CABG), presence of ST-segment depressionand total ischemic duration (60 minutes). Statistical significance was acceptedat p cO.05. RESULTS
Uinical drsracteristies: Ambulatory ECG examination of the 94 patients examined early after CABG detected 19 (20%) patients with transient ST depression,8 (9%) patients with transient ST elevation and 67 (71%) patients without ST-segment changes. Similarly, of 184 patients examined late after CABG, 50 (27%) patients showedtransient ST depression,13 (7%) patients showed transient ST elevation and 121 (66%) patients had no ST-segment changes. All patients with ST-segment depressionwere asymptomatic, with the exception of 2 patients in the early group, and 1 patient in the late group who also had typical angina. The clinical characteristics of 86 early and 171 late patients with and without silent ischemia detected after CABG are listed in Table 1. No significant differences were found betweenpatients with or without silent ischemia except for the increased use of nitrates in silent ischemia patients in the late group. Significantly (p
2 mm over baseline. Analysis of the data with or without inclusion of these patients was not significantly different, and their findings were included. Virtually all episodes (99%) of transient ST-segment depressiondetected were asymptomatic. The circadian distribution of the time of occurrence of number of episodesand minutes of ischemicduration are listed in Figure 1. The frequency of ischemic episodessignificantly peakedin the morning hours between 6 A.M. and 12 noon, and a second modal peak was ob servedbetween6 P.M.and midnight in patients both early and late after CABG (analysis of variance: early, p =
Early Posti s$BG Group 12 24 u .g 20 8
16
h
150 175
D”, $ -9 2 Ee
:: 75 50
5 B
“0 12 b 8 G4 a 2
.2
250 22s 200
h ’
12 3 -,-L--p-
6
9
12
3
6
9
’
12 3 6 9 -am-L-pm-----J
12
3
6
9
Time of Day
Time of Day
Late Post - CABG Group (N=SO) $
24
450 500
3 .Yn
20
.B * 400 f-3 v) Y 350 ‘0 $300
w 3 k
16 12 8
iIn .I; z ;
Pp ‘O” rem
z4 Z’O
12 3 -m--p-
6
9
12
3
6
9
Time of Day A. FtGuRE Me-
1. Hady
250 200 150
~oftoWnunbaot~(A)rdtoW~otST~~(B)daeckdhlS emty(1to3momths)mdSOpatbmtsexm&md
’
12 I
3
12
3
6
9
Time of Day
H Symptomatic
0
6 9 am--pm-
B.
Silent
late(12madhs)attarczorawy
=-Ybl=-Pmfm
mw.
THE AMERICAN
JOURNAL
OF CARDIOLOGY
JANUARY
1. 1990
17
TA8l.E III Angiographic and Hemodynamic Characteristics of Patients Examined Early (1 to 3 Months) and Late (12 Months) After CABG With and Without Evidence of Silent lschemia Detected by Ambulatory Electrocardiography Late After CABG
Early After CABG
Characteristics No. of vessels with >70% stenosis* 1 2 3 Left main 250% No. of grafts 0 SVG 1 SVG 2 SVG 3 SVG 4 SVG 1%
2seq 1Y 1 IMA 2 IMA 1 IMASeq Mean grafts/pt Mean anastomotic sites/pt EF before CABG’ EF after CABG No. of patients EF 240 EF 40 LVEDP (mm Hg) before CAffi LVEDP (mm Hg) after CABG
Silent lschemia (n = 19)
No lschemia (n = 67)
Silent lschemla (n = 50)
2 6 11 2
10 33 24 5
5 25 20 7
1 12 5 1 0 9 2 2 7 0 2 2.7 f 1.0 3.6 f 0.8 66f12 68f14
11 32 21 2 1 33 9 5 18 2 11 2.7 f 3.7 f 64f 67f
8 28 9 5 0 27 4 6 16 1 6 2.6 f 3.6 f 64f 64*
17 0 13f5 lOf5
60
l Lefl man &ease inch&d as P-vessel disease. and 2 patents mung CABG - corcwwy arlety bypass grafting: EF - epctm lracl~on: IMA graft; SVG = &ated saphenous van &t: Y - Y-graft (2 Iambs).
2 13f7 llf6
13 47 59 20
48 2 13f8 llf5
fn the grcup late after CABG because of 50% steoov~;
0.7 1.0 15 14
12 48’ 519 8 2 54 7 6 41 4 20 2.7 f 0.6 3.6 f 1.0 66f15 65f13 117 4 12f6 11 f4
’ not all patients had EF: ’ p cO.05: 5 p
