Scientific letter Incidence and Prognosis of Mechanical Complications of STEMI After Primary Angioplasty: Data From a Single-center Registry of an Infarction Code Program

To the Editor,

Mechanical complications (MC) of ST-segment-elevation acute myocardial infarction (STEMI) are an important cause of morbidity and mortality and dramatically worsen prognosis. The introduction of early reperfusion therapy has significantly reduced the classical incidence of MC (5%-10%).^1,2 In particular, the widespread use of primary angioplasty (PA) has reduced its current incidence to between 1% and 2%.^3,4 The implementation of regional PA programs has decreased reperfusion times and improved prognosis, most likely due to the decreased incidence of MC. We evaluated the incidence, treatment, course, and predictors of MC in a cohort who underwent PA under a STEMI emergency treatment protocol, in which fibrinolysis was only used when there were delays or logistic difficulties.

Four researchers retrospectively reviewed the medical records of 950 consecutive patients who underwent PA between 2005 and 2012 with hospital and 30-day follow-up. Qualitative variables are expressed as percentages and quantitative variables as mean or median ± standard deviation according to the normality of the distribution. The Student t test was used to compare means and chi-square for percentages. Univariable and multivariable analyses were used to identify the predictors of MC. A P value of < .05 was used as a cutoff for statistical significance.

The incidence of MC was 2.02% (19 patients). Of these patients, 14 (73.6%) had free wall rupture (FWR), 2 (10.5%) had interventricular septal rupture (IVSR), and 3 (15.8%) had papillary muscle rupture (PMR). Most MCs occurred within 24 hours of admission (52.6%) and a significant proportion (26.3%) occurred after 96 hours. Table 1 shows the baseline characteristics of the patients and Table 2 shows the characteristics of the patients with MCs. The median total times of ischemia (symptoms-to-balloon) and door-to-balloon were nonsignificantly higher in the MC group. Regarding treatment and in-hospital course, 7 patients died (36.8%) and 10 patients (52.6%) were referred to cardiac surgery. One patient died before surgery, but the remaining 9 patients survived. All patients with PMR or IVSR underwent surgery, whereas 5 (35.7%) of the patients with FWR underwent surgery and 5 with FWR (35.7%) underwent intensive medical treatment. Patients with IVSR did not undergo percutaneous treatment due to its lack of availability. These treatment options were not applicable in the remaining patients with FWR (28.6%), because of sudden death. Logistic regression analysis showed that the only independent predictors of events were female sex (odds ratio [OR] = 4.03; confidence interval 95% [95%CI], 1.2-14.9; P = .022) and Killip class III-IV (OR = 1.95; 95%CI, 1.9-4.5; P < .0001).

Table 1.

Baseline Characteristics of Patients With and Without Mechanical Complications and Their Comparison

	MC (n = 19)	Without MC (n = 931)	P
Age, y	76.8 ± 8.9	65 ± 13.5	<.01
Men, %	52.6	80.2	<.01
BMI	25.3	28.2	.54
HT, %	52.6	59.5	.54
DM, %	36.8	26.4	.77
Dyslipidemia, %	57.9	42.9	.19
Smoking, %	41.2	21.1	.12
Previous ischemic heart disease, %	5.3	11.7	.38
Peripheral artery disease, %	0	8.3	.19
CCR < 60 mL/min, %	20.1	17	.22
Site of AMI			.35
Anterior/septal, %	61.1	44.4
Inferior/posterior, %	16.7	25.7
Lateral, %	3.3	9.8
Other, %	18.9	20.1
Culprit artery			.79
LMCA, %	0	0.4
AD territory, %	57.9	43.7
RC territory, %	31.7	44.2
Cx territory, %	10.4	11.7
Killip class ≥ III, %	68.8	12.1	<.01
Multivessel disease, %	57.9	57.6	.97
Total ischemia time, min	360 [210-448]	240 [170-350]	.62
Door-to-balloon time, min	87 [46-210]	70 [36-120]	.18
IABPC, %	5.3	2.2	.37
Hospital mortality, %	36.8	4.0	<.01

AD, anterior descending; AMI, acute myocardial infarction; BMI, body mass index; CCR, creatinine clearance rate; Cx, circumflex; DM, diabetes mellitus; HT, hypertension; IABCP, intra-aortic balloon counter pulsation; LMCA, left main coronary artery; MC, mechanical complication; RC, right coronary.

Unless otherwise specified, values are expressed as mean ± standard deviation or median [interquartile range].

Table 2.

Characteristics of Patients With Mechanical Complications

Patient	Type of MC	Year of MC	Moment of MC^a	Sex	Age, y	CA	Killip class at admission	LVEF at admission, %	Successful PCI^b	TTI, min	DBT, min	CVS	Mortality
													Hospital	30 d
1	FWR	2005	3rd day	Woman	82	RCd	IV	60	No	460	320	No^c	Yes	—
2	IVSR	2006	1st day	Man	85	ADi	I	40	Yes	420	NA	Yes	Yes
3	FWR	2006	4th day	Woman	83	ADi	IV	NA	No	210	90	No	Yes	—
4	FWR	2007	1st day	Man	74	RCp	I	55	Yes	360	180	Yes	No	No
5	FWR	2007	11th day	Man	43	ADp	III	25	Yes	> 48 h	NA	Yes	No	No
6	FWR	2008	2nd day	Man	79	RCp	IV	55	Yes	210	30	Yes	No	No
7	FWR	2008	1st day	Man	77	ADp	IV	35	Yes	360	220	No	No	No
8	PMR	2009	1st day	Man	87	RCi	IV	60	Yes	240	45	Yes	Yes	—
9	FWR	2009	8th day	Man	83	ADp	II	35	Yes	300	50	No	No	No
10	FWR	2010	1st day	Woman	79	ADi	IV	30	Yes	420	40	No^c	Yes	—
11	FWR	2010	1st day	Woman	73	OM2	II	NA	Yes	240	180	No^c	Yes	—
12	FWR	2010	3rd day	Woman	80	ADp	IV	30	No	360	75	No	No	No
13	FWR	2010	5th day	Woman	83	ADd	II	45	No	390	100	Yes	No	No
14	FWR	2011	4th day	Man	80	ADp	IV	30	Yes	210	90	Yes	No	No
15	FWR	2011	1st day	Man	76	ADp	I	NA	No	330	—	No^c	Yes	—
16	FWR	2012	3rd day	Woman	81	RCp	I	55	Yes	150	45	No	No	No
17	PMR	2012	1st day	Man	79	CX-OM1	III	70	Yes	90	75	Yes	No	No
18	PMR	2012	1st day	Woman	68	RCi	IV	60	Yes	510	55	Yes	No	No
19	IVSR	2012	1st day	Woman	78	ADi	IV	50	Yes	720	120	Yes	No	No

AD, anterior descending; CA, culprit artery; CVS, cardiovascular surgery; CX-OM1, circumflex-first marginal; d, distal; DBT, door-to-balloon time; FWR, free wall rupture; i, intermediate; IVSR, interventricular septal rupture; LVEF, left ventricular ejection fraction; MC, mechanical complication; NA, not available; OM2, second marginal; p, proximal; PCI, percutaneous coronary intervention; PMR, papillary muscle rupture; RC, right coronary; TIMI, Thrombolysis in Myocardial Infarction; TTI, total time of ischemia.

a

Time of MC after admission.

b

PCI was considered successful if it was possible to revascularize the culprit artery without complications and with TIMI III flow.

c

CVS not scheduled due to abrupt clinical presentation of MC as sudden death.

The incidence of MC was similar to that described in the literature^1,2, but clearly lower than its incidence (5%-10%) in the period before widespread implementation of systematic reperfusion. Some characteristics have already been described as predictors of MC: female sex and longer ischemia times.⁴ In our series, Killip class III-IV was also an independent predictor of MC.

Current guidelines⁵ recommend surgery as the treatment of choice; however, some patients are not candidates for emergency surgery because of instability, age, and comorbidity. In addition, the optimal timing of surgical treatment remains to be established. Surgical mortality in these patients is considerable and is clearly influenced by those who survive the first days of stabilization under intensive measures, which constitutes a selection bias in most of the reported results. In our series, 52.6% of patients were referred to surgery, and around half of the patients with FWR received intensive medical treatment with acceptable results. Most of these patients had subacute FWR, which successfully responds to nonsurgical treatment.⁶

Regardless of treatment, prognosis is clearly worse in these patients and depends on the type of MC. In a series published by French et al.,⁴ in-hospital survival and 90-day survival were 97% and 96% in patients without MC, respectively. However, in-hospital survival and 90-day survival were 43% and 27% in patients with FWR, 73% and 73% in those with PMR, and 60% and 20% in those with IVSR, respectively. Overall 30-day survival was 63.2%, which varied according to the type of MC: 64.3% in FWR, 66.6% in PMR, and 50% in IVSR.

In conclusion, the incidence of MC has decreased in the era of PA, but remains associated with high mortality; however, the mortality rate could decrease in a group selected for surgery. Early diagnosis and treatment would be improved by remaining alert to the specific characteristics of each patient. The incidence of MC could be reduced by the widespread use of PA protocols with shorter ischemia times. Multicenter registries with more patients are needed to better understand the predictors of MC and to determine which subgroups would derive the most benefit from surgical treatment.