Mechanical Dyssynchrony Combined with Septal Scarring Reliably Identifies Responders to Cardiac Resynchronization Therapy

Background and aim: The presence of mechanical dyssynchrony on echocardiography is associated with reverse remodelling and decreased mortality after cardiac resynchronization therapy (CRT). Contrarily, myocardial scar reduces the effect of CRT. This study investigated how well a combined assessment of different markers of mechanical dyssynchrony and scarring identifies CRT responders. Methods: In a prospective multicentre study of 170 CRT recipients, septal flash (SF), apical rocking (ApRock), systolic stretch index (SSI), and lateral-to-septal (LW-S) work differences were assessed using echocardiography. Myocardial scarring was quantified using cardiac magnetic resonance imaging (CMR) or excluded based on a coronary angiogram and clinical history. The primary endpoint was a CRT response, defined as a ≥15% reduction in LV end-systolic volume 12 months after implantation. The secondary endpoint was time-to-death. Results: The combined assessment of mechanical dyssynchrony and septal scarring showed AUCs ranging between 0.81 (95%CI: 0.74-0.88) and 0.86 (95%CI: 0.79-0.91) for predicting a CRT response, without significant differences between the markers, but significantly higher than mechanical dyssynchrony alone. QRS morphology, QRS duration, and LV ejection fraction were not superior in their prediction. Predictive power was similar in the subgroups of patients with ischemic cardiomyopathy. The combined assessments significantly predicted all-cause mortality at 44 ± 13 months after CRT with a hazard ratio ranging from 0.28 (95%CI: 0.12-0.67) to 0.20 (95%CI: 0.08-0.49). Conclusions: The combined assessment of mechanical dyssynchrony and septal scarring identified CRT responders with high predictive power. Both visual and quantitative markers were highly feasible and demonstrated similar results. This work demonstrates the value of imaging LV mechanics and scarring in CRT candidates, which can already be achieved in a clinical routine.

Lateral Wall Dysfunction Signals Onset of Progressive Heart Failure in Left Bundle Branch Block

OBJECTIVES

This study sought to investigate if contractile asymmetry between septum and left ventricular (LV) lateral wall drives heart failure development in patients with left bundle branch block (LBBB) and whether the presence of lateral wall dysfunction affects potential for recovery of LV function with cardiac resynchronization therapy (CRT).

BACKGROUND

LBBB may induce or aggravate heart failure. Understanding the underlying mechanisms is important to optimize timing of CRT.

METHODS

In 76 nonischemic patients with LBBB and 11 controls, we measured strain using speckle-tracking echocardiography and regional work using pressure-strain analysis. Patients with LBBB were stratified according to LV ejection fraction (EF) ≥50% (EF_preserved), 36% to 49% (EF_mid), and ≤35% (EF_low). Sixty-four patients underwent CRT and were re-examined after 6 months.

RESULTS

Septal work was successively reduced from controls, through EF_preserved, EF_mid, and EF_low (all p < 0.005), and showed a strong correlation to left ventricular ejection fraction (LVEF; r = 0.84; p < 0.005). In contrast, LV lateral wall work was numerically increased in EF_preserved and EF_mid versus controls, and did not significantly correlate with LVEF in these groups. In EF_low, however, LV lateral wall work was substantially reduced (p < 0.005). There was a moderate overall correlation between LV lateral wall work and LVEF (r = 0.58; p < 0.005). In CRT recipients, LVEF was normalized (≥50%) in 54% of patients with preserved LV lateral wall work, but only in 13% of patients with reduced LV lateral wall work (p < 0.005).

CONCLUSIONS

In early stages, LBBB-induced heart failure is associated with impaired septal function but preserved lateral wall function. The advent of LV lateral wall dysfunction may be an optimal time-point for CRT.

Regional myocardial work as determinant of heart failure in left bundle branch block

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Background

Left bundle branch block (LBBB) worsen prognosis in heart failure patients. LBBB may also cause heart failure in otherwise healthy individuals. The mechanical changes induced by LBBB are potential determinants of heart failure in these patients, but their relation to left ventricular (LV) systolic function is incompletely understood.

Purpose

This study investigates the contribution of regional contractile function to heart failure in patients with LBBB.

Methods

In 76 patients with LBBB and 11 healthy controls, myocardial strain was measured by speckle-tracking echocardiography and myocardial work by pressure-strain analysis. Patients with ischemic heart disease or myocardial scarring were excluded. LBBB patients were stratified by LV ejection fraction (EF) &gt;50% (EFpreserved), 36-50% (EFmid), and ≤35% (EFlow). 62 LBBB patients subsequently underwent cardiac resynchronization therapy (CRT) implantation and was re-examined at 6 months.

Results

Septal work was significantly and successively reduced from controls, EFpreserved, EFmid, to EFlow (1977 ± 506, 1025 ± 342, 601 ± 494 and -41 ± 303 mmHg·%, respectively, all p &lt; 0.01) (Figure 1). There was a strong correlation (R = 0.84, p &lt; 0.01) between septal work and LVEF. In contrast, work in the LV lateral wall was preserved in both EFpreserved (2367 ± 459 mmHg·%) and EFmid (2252 ± 449 mmHg·%) vs controls (2062 ± 459 mmHg·%, all NS). In the EFlow group, however, LV lateral wall work was reduced (1473 ± 568 mmHg·%, p &lt; 0.01 vs controls). Thus, lateral wall function was not correlated with LVEF in patients with LVEF &gt;35% (NS). At six month CRT septal work was markedly increased (165 ± 485 vs 1288 ± 523 mmHg·%, p &lt; 0.01) and LV lateral wall work reduced (1730 ± 620 vs 1264 ± 490 mmHg·%, p &lt; 0.01). LVEF increased from 32 ± 8 to 47 ± 10 % (p &lt; 0.01).

Conclusions

Heart failure in LBBB patients is determined by degree of septal dysfunction. LV lateral wall function, on the other hand, is preserved in the early phase of heart failure and was only reduced in patients with severe heart failure. Further clinical studies should investigate if measuring LV lateral wall function can increase precision in patient selection for CRT.

Abstract Figure.

Elevated septal wall stress - a driver of left ventricular dysfunction in left bundle branch block?

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): The Norwegian Health Association

Background

Septal dysfunction is a main feature of left bundle branch block (LBBB), and increasing wall stress is a proposed mechanism of heart failure development in LBBB patients. To try to reveal the pathophysiologic pathway from dyssynchrony to heart failure, we investigated the relationship between septal and left ventricular (LV) lateral wall stress in patients with LBBB.

Hypothesis

Increased septal wall stress causes septal dysfunction in LBBB.

Methods

We included 24 LBBB-patients (65 ± 11 years, 11 males) with LV ejection fraction (EF) ranging from 18 to 67%, and 8 healthy controls (58 ± 10 years, 4 males). Wall stress was calculated at peak LV pressure (LVP) according to the law of La Place ([LVP x radius]/[wall thickness]). Wall thickness was measured using M-mode, and regional curvature was measured in mid-ventricular shortaxis from 2D echocardiographic images. We used a previously validated non-invasive method to estimate LVP from brachial blood pressure and adjusted for valvular events. Myocardial scar was ruled out by late gadolinium enhancement cardiac magnetic resonance imaging.

Results

Wall stress was significantly higher in septum than LV lateral wall at peak LVP (48 ± 12 vs 37 ± 11 kPa, p &lt; 0.01) in LBBB patients, while no difference was seen in the controls (Figure A). In patients, septal wall thickening showed a strong correlation with LVEF (r = 0.77, p &lt; 0.01) (Figure B). Similar correlation was not significant for the LV lateral wall (r = 0.13, NS). Attenuation of septal wall thickening in LBBB-patients correlated well with increasing septal wall stress (r=-0.60, p &lt; 0.01). Wall thickening and stress did not correlate in the LV lateral wall (r=-0.14, NS).

Conclusion

Increased septal wall stress is associated with reduced systolic thickening in patients with LBBB. Septal wall thickening, in contrast to LV lateral wall thickening, was correlated to global LV function. These findings suggest that septal remodeling which could have normalized septal wall stress, was not achieved and heart failure may develop.

Abstract Figure.

P1585 Cardiac magnetic resonance estimated extracellular volume fraction, but not native T1 mapping, detects scar in patients referred for cardiac resynchronization therapy

Funding Acknowledgements

The study was supported by Center for Cardiological Innovation

Background

Myocardial scar burden (focal fibrosis) is associated with poor response to cardiac resynchronization therapy (CRT), and should preferably be detected prior to device implantation. Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) is considered reference standard for scar detection, but is not available in renal failure. Diffuse fibrosis is assessed by T1 mapping CMR with or without calculation of extracellular volume fraction (ECV). The method is vulnerable to partial volume effects, thus subendocardial tissue is most often not included in mapping analyses. Whether the contrast-free native T1mapping could replace LGE in the preoperative evaluation of patients referred for CRT is unknown.

Purpose

To investigate if native T1 mapping and calculation of ECV can adequately detect scar in patients referred for CRT.

Methods

Scar was quantified as percentage segmental LGE in 45 patients (age 65 ± 10 years, 71% male, QRS-width 165 ± 17ms) referred for CRT. In total 720 segments were analyzed, and LGE≥50% was considered transmural scar. T1-mapping before and after contrast agent injection was performed in all patients. ECV was calculated based on the ratio between tissue T1 relaxation change and blood T1 relaxation change after contrast agent injection, corrected for the haematocrit level. The agreement between native T1/ECV and scar was evaluated with receiver operating characteristic (ROC) curves with calculation of area under the curve (AUC) and 95% confidence interval (CI).

Results

LGE was present in 255 segments, 465 segments were without LGE. Average native T1 in segments with LGE was 1028 ± 88 ms, and 1040 ± 60 ms in segments without LGE (p = 0.16). The corresponding numbers for ECV were 38.7 ± 10.9% and 30.0 ± 4.7%, p &lt; 0.001. Native T1 showed poor agreement to scar independent of scar size (AUC = 0.532, 95% CI 0.485-0.578 for scars of all sizes, and AUC = 0.572, 95% CI 0.495-0.650 for transmural scars). ECV, on the other hand, showed reasonable agreement with scar of all sizes (AUC = 0.777, 95% CI 0.739-0.815), and good agreement with transmural scars (AUC = 0.856, 95% CI 0.811-0.902). (Figure)

Conclusion

The contrast-free CMR technique T1 mapping does not adequately detect scars in patients referred for CRT. Adding post contrast T1 measurements and calculating ECV improves accuracy, especially for transmural scars. Future studies should investigate if diffuse fibrosis could be predictive of CRT response.

Abstract P1585 Figure. Detection of transmural scars

Stenting small coronary arteries using two second-generation slotted tube stents: acute and six-month clinical and angiographic results

This prospective study assessed the feasibility, safety, as well as clinical and angiographic outcome after 6 months in 96 patients (100 lesions) treated by stent implantation after a suboptimal balloon angioplasty result in coronary arteries < 3 mm and with a lesion length < 25 mm. The lesions were randomized to treatment with BeStent small or NIR-7. Final quantitative coronary angiography was performed off line. Baseline reference diameter was 2.58 +/- 0.22 mm. Complex lesions constituted 52%, and 23% had unstable angina. Angiographic and procedural success was achieved in 98% and 94%, respectively. At follow-up, 88.5% were free of major adverse cardiac events. The overall restenosis rate was 22.5% (89% angiographic follow-up). There were no statistically significant differences between the stents regarding predefined endpoints. Thus, provisional stent treatment of small coronary arteries using BeStent small or NIR-7 is feasible, safe, and has a favorable clinical and angiographic mid-term outcome.

N-terminal proatrial natriuretic peptide in angina pectoris: impact of revascularization by angioplasty

AIMS

We investigated whether levels of N-terminal proatrial natriuretic peptide (N-terminal proANP) reflect the severity of coronary artery disease in chronic, stable angina pectoris. Furthermore, we investigated if revascularization by percutaneous transluminal coronary angioplasty (PTCA) affected the N-terminal proANP level and, finally, whether restenosis could be predicted by changes in N-terminal proANP after PTCA.

METHODS AND RESULTS

N-terminal proANP was measured in 286 patients before and after PTCA. The patients' baseline level of N-terminal proANP (787+/-403 pmol/l) correlated significantly with left ventricular end diastolic pressure, age and serum creatinine, but not with the number of stenotic vessels. Twenty-four hours post-PTCA N-terminal proANP decreased significantly, and completely revascularized patients demonstrated a decline two-fold larger than those incompletely revascularized (deltaN-terminal proANP -114+/-178 vs. -53+/-231 pmol/l, P<0.05). After 14 days N-terminal proANP had returned to baseline in both groups. Changes in N-terminal proANP from post-PTCA to the final follow-up was not predictive of angiographic restenosis.

INTERPRETATION

The significant decrease in N-terminal proANP observed after angioplasty, most pronounced in patients completely revascularized, is thought to reflect a transient improvement in resting left ventricular function.

Predictors for restenosis after angioplasty of chronic coronary occlusions

BACKGROUND

The Stenting In Chronic Coronary Occlusion (SICCO) study assessed the effects of additional intracoronary stenting (Palmaz-Schatz) after successful percutaneous transluminal coronary angioplasty (PTCA) of chronic coronary occlusions and showed a significant reduction of restenosis in stented patients.

METHODS

Univariate and logistic regression analyses were used to assess clinical, angiographic and procedure related predictors for restenosis (>50% diameter stenosis at follow-up) and Major Adverse Clinical Events (MACE=cardiac death, lesion-related acute myocardial infarction, repeat lesion-related angioplasty, bypass surgery involving the treated segment or angiographic documentation of reocclusion in non-revascularized patients) in the 114 SICCO patients with an angiographic end-point and 300 days clinical follow-up.

RESULTS

By 6 months the restenosis rate was 53%, and after 300 days MACE had occurred in 39%. Both the rates of restenosis and MACE was significantly reduced by stenting. The restenosis rate was improved by stenting also in patients with a 'stentlike' result after the initial PTCA. In the multivariate model the risk of restenosis was increased by a history of unstable angina, a long lesion and a non-tapering occlusion stump. LAD location was associated with a threefold increased risk of MACE.

CONCLUSION

Stent implantation should always be considered in successfully opened chronic occlusions.

Sustained benefit of stenting chronic coronary occlusion: long-term clinical follow-up of the Stenting in Chronic Coronary Occlusion (SICCO) study

OBJECTIVES

This study assessed the long-term clinical outcome of stenting chronic occlusions.

BACKGROUND

In the Stenting in Chronic Coronary Occlusion (SICCO) study, patients were randomized to additional stent implantation (n = 58) or not (n = 59) after successful recanalization and dilation of a chronic coronary occlusion. Palmaz-Schatz stents were used with full anticoagulation. The previously published 6-month angiographic follow-up results showed reduction of the restenosis rate from 74% to 32%.

METHODS

The primary end point was the occurrence of major adverse cardiac events (cardiac death, lesion-related acute myocardial infarction, repeat lesion-related revascularization or angiographic documentation of reocclusion).

RESULTS

Late clinical follow-up was obtained in all patients at 33 +/- 6 months. Major adverse cardiac events occurred in 14 patients (24.1%) in the stent group compared with 35 patients (59.3%) in the percutaneous transluminal coronary angioplasty (PTCA) group (odds ratio 0.22, 95% confidence interval 0.10 to 0.49, p = 0.0002). Target vessel revascularization (including failed PTCA attempts) was performed in 24% of the stent group and in 53% of the PTCA group (p = 0.002). There were no events in the stent group after 8 months, whereas events continued to occur in the PTCA group. By multivariate analysis, allocation to the PTCA group, left anterior descending coronary artery lesion and lesion length were significantly related to the development of major adverse cardiac events.

CONCLUSIONS

These data demonstrate the long-term safety and clinical benefit of stenting recanalized chronic occlusions. There is a continued risk of late clinical events related to nonstented lesions. Implantation of an intracoronary stent should therefore be considered after successful opening of a chronic coronary occlusion.

The Barath Cutting Balloon versus conventional angioplasty. A randomized study comparing acute success rate and frequency of late restenosis

In a randomized multicenter study initial success rate and 6 months' follow-up were compared between coronary angioplasty performed with the Barath Cutting Balloon (group A, n = 32) and conventional balloons (group B, n = 32) in patients with type A or B lesions in native coronary arteries. The culprit lesion was not reached in one patient in group A. Initial success rates were similar with and without additional stenting (8 in group A and 10 in group B). Angiographic follow-up data (in 95%) revealed a non-significant improvement in minimal lumen diameter, diameter stenosis in group A. Restenosis developed in 16.7% of group A vs 25.8% of group B, (p = 0.57). A separate analysis of stented patients showed no restenosis in group A and restenosis in 4 out of 10 patients in group B (p = 0.10). A possible beneficial effect of the Cutting Balloon with respect to in-stent restenosis requires further studies.

Improvement in left ventricular ejection fraction and wall motion after successful recanalization of chronic coronary occlusions

AIMS

This study assessed changes in left ventricular ejection fraction and regional radial shortening after successful angioplasty of chronic coronary occlusions.

METHODS

We studied 95 patients with angina pectoris or exercise-induced ischaemia with a successfully recanalized chronic (median duration 4.3 months) coronary occlusion. Intracoronary stents were implanted in 71%. Left ventriculograms were obtained at baseline and after 6.7 +/- 1.4 months. Left ventricular ejection fraction and regional radial shortening were determined by a computer-assisted method.

RESULTS

Left ventricular ejection fraction increased from 0.62 +/- 0.13 at baseline to 0.67 +/- 0.11 at follow-up (P < 0.001). The change in left ventricular ejection fraction in patients with a patent artery and in patients with reocclusion (n = 8) was 0.05 +/- 0.06 and 0.01 +/- 0.04, respectively (P = 0.04). Regional radial shortening in the territory of the recanalized artery increased by 16% (from 0.28 +/- 0.11 to 0.32 +/- 0.11, P < 0.001) in patients with a patent artery at follow-up, but was unchanged in patients with reocclusion.

CONCLUSION

Long-term patency after recanalization of old, chronic coronary occlusions in patients with angina pectoris is associated with improvement in global and regional left ventricular function. This may be a result of recovery of hibernating myocardium and supports the strategy of recanalizing chronic coronary occlusions.

Stenting in Chronic Coronary Occlusion (SICCO): a randomized, controlled trial of adding stent implantation after successful angioplasty

OBJECTIVES

This study investigated whether stenting improves long-term results after recanalization of chronic coronary occlusions.

BACKGROUND

Restenosis is common after percutaneous transluminal coronary angioplasty (PTCA) of chronic coronary occlusions. Stenting has been suggested as a means of improving results, but its use has not previously been investigated in a randomized trial.

METHODS

We randomly assigned 119 patients with a satisfactory result after successful recanalization by PTCA of a chronic coronary occlusion to 1) a control (PTCA) group with no other intervention, or 2) a group in which PTCA was followed by implantation of Palmaz-Schatz stents with full anticoagulation. Coronary angiography was performed before randomization, after stenting and at 6-month follow-up.

RESULTS

Inguinal bleeding was more frequent in the stent group. There were no deaths. One patient with stenting had a myocardial infarction. Subacute occlusion within 2 weeks occurred in four patients in the stent group and in three in the PTCA group. At follow-up, 57% of patients with stenting were free from angina compared with 24% of patients with PTCA only (p < 0.001). Angiographic follow-up data were available in 114 patients. Restenosis (> or = 50% diameter stenosis) developed in 32% of patients with stenting and in 74% of patients with PTCA only (p < 0.001); reocclusion occurred in 12% and 26%, respectively (p = 0.058). Minimal lumen diameter (mean +/- SD) at follow-up was 1.92 +/- 0.95 mm and 1.11 +/- 0.78 mm, respectively (p < 0.001). Target lesion revascularization within 300 days was less frequent in patients with stenting than in patients with PTCA only (22% vs. 42%, p = 0.025).

CONCLUSIONS

Stent implantation improved long-term angiographic and clinical results after PTCA of chronic coronary occlusions and is thus recommended regardless of the primary PTCA result.

Reproducibility of quantitative coronary analysis, Assessment of variability due to frame selection, different observers, and different cinefilmless laboratories

Because of limited storage capacity for digital images, angiographic laboratories without cinefilm are dependent on locally performed quantitative coronary angiography (QCA) in clinical studies. In the present study the intra- and interobserver variability, as well as variability between different laboratories and variability due to frame selection was analyzed. A total of 20 coronary lesions were studied in two different laboratories 12 +/- 8 days apart. Images were analyzed on-line and after being transferred to a Cardiac Work Station (CWS). There was no significant difference between the measurement situations. For minimal luminal diameter (MLD) precision (SD of signed errors) ranged from 0.12 mm to 0.20 mm, for reference diameter (RD) from 0.15 mm to 0.28 mm, and for percent diameter stenosis (DS) from 4.2% to 5.8%. Overall relative precision was obtained by normalizing the QCA parameters, as well 11.9% for MLD, 7.0% for RD and 8.5% for DS (p < 0.001, Rd and DS compared to MLD). The overall variability in the interobserver and in the interlaboratory comparisons was 11.2% and 10.4%, respectively (n.s) (n.s.). Thus the variability of QCA performed in cinefilmless, digital laboratories is small, and within a range making it an useful tool for clinical practice and group comparisons in clinical studies. However, the error range of QCA measurements must be taken into consideration when judging results from individual patients.

[Should older patients be admitted for coronary evaluation and treatment? With special emphasis on a survey and catheter-based revascularization of patients over 70 years of age]

A three year survey of patients undergoing diagnostic left heart catheterization and PTCA treatment is presented from Feiringklinikken. Data on patients over and under 70 years have been analysed separately. The fraction of patients over 70 years admitted for catheterization increased significantly from 18.8% to 23.4% during the survey period. Angiography was associated with a low mortality of 0.04% and incidence of cerebrovascular complications with 0.1%, with no increased risk in patients over 70 years. The proportion of patients treated with PTCA increased significantly during the survey from 25% to 39% for patients over 70 years and from 31% to 42% for patients under 70 years (p < 0.01). The initial success rate of PTCA was 89% and 92% for patients over and under 70 years respectively (not significant). The rate of serious complications was low in both age groups, 3.2% and 1.0% in patients over and under 70 years respectively (p < 0.01). Older patients can be examined invasively with low risk of complications. A substantial number of patients, also among the elderly, can be treated safely with PTCA with good initial results. Thus, elderly patients should be offered the benefit of invasive diagnosis and treatment for coronary heart disease.

Factor VII and extrinsic pathway inhibitor in acute coronary disease

This report describes studies on the activation of coagulation factor VII (FVII) and the inhibition of the extrinsic coagulation pathway in acute ischaemic heart disease. FVII and the inhibitor of the tissue thromboplastin-FVII complex, called extrinsic pathway inhibitor (EPI), were determined in plasma from 68 patients and compared to findings in 37 normal individuals. The mean FVII amidolytic activity, the mean FVII clotting activity, as well as the FVII clotting/FVII amidolytic ratio were not significantly different in the patient groups as compared to the controls. The fraction of FVII clotting activity that is sensitive to phospholipase C, 'the FVII-phospholipid complex', was 8% in controls, 19% (P less than 0.05) in patients with acute myocardial infarction, 15% (n.s.) in angina pectoris and 13% (n.s.) in heart failure/arrhythmia patients. The 'FVII-phospholipid complex' was highly significantly correlated to triglycerides in plasma in patients with acute myocardial infarction (r = 0.88, P less than 0.001) and angina pectoris (r = 0.89, P less than 0.001). The mean EPI levels were significantly increased in patients with acute myocardial infarction (132%), angina pectoris (134%), and heart failure (150%) as compared to the control population (110%). The FVII clotting/EPI ratio was significantly decreased both in patients with acute myocardial infarction and heart failure, whereas the FVII amidolytic/EPI ratio was significantly decreased only in the heart failure group. Apparently, in patients with acute ischaemic heart disease, a moderate increase in the procoagulant activity is accompanied by a marked increase in the anticoagulant activity of the extrinsic coagulation pathway, suggesting a balanced activation system.

Evolution of infarct size during the early use of nifedipine in patients with acute myocardial infarction: the Norwegian Nifedipine Multicenter Trial

In a multicenter double-blind study, 227 patients with suspected acute myocardial infarction (AMI) were randomized within 12 hr from onset of symptoms to treatment with nifedipine (112 patients) or placebo (115 patients). AMI was confirmed in 74 patients on nifedipine and in 83 on placebo. Patients with AMI received nifedipine 5.5 +/- 2.9 hr (mean +/- SD) after onset of symptoms. Infarct size was assessed by the release of creatine kinase isoenzyme MB (CK-MB). Infarct size index (CK-MB geq/m2) was 25 +/- 16 (n = 71) in the nifedipine group and 23 +/- 13 (n = 77) in the placebo group (NS). After the first 10 mg of nifedipine systolic blood pressure fell from 147 +/- 30 to 135 +/- 28 mm Hg (p less than .01) and heart rate rose from 75 +/- 18 to 79 +/- 19 beats/min (p less than .01). No change was observed after the first placebo dose. The treatment was continued for 6 weeks. Over this period there were 10 deaths in each group. Early treatment with nifedipine in patients with AMI does not seem to reduce infarct size as determined by enzyme level.